1
|
Creech CJ, Hope JM, Zarkou A, Field-Fote EC. Optimizing assessment of low frequency H-reflex depression in persons with spinal cord injury. PLoS One 2024; 19:e0300053. [PMID: 38743683 PMCID: PMC11093375 DOI: 10.1371/journal.pone.0300053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 02/04/2024] [Indexed: 05/16/2024] Open
Abstract
Considering the growing interest in clinical applications of neuromodulation, assessing effects of various modulatory approaches is increasingly important. Monosynaptic spinal reflexes undergo depression following repeated activation, offering a means to quantify neuromodulatory influences. Following spinal cord injury (SCI), changes in reflex modulation are associated with spasticity and impaired motor control. To assess disrupted reflex modulation, low-frequency depression (LFD) of Hoffman (H)-reflex excitability is examined, wherein the amplitudes of conditioned reflexes are compared to an unconditioned control reflex. Alternatively, some studies utilize paired-pulse depression (PPD) in place of the extended LFD train. While both protocols induce similar amounts of H-reflex depression in neurologically intact individuals, this may not be the case for persons with neuropathology. We compared the H-reflex depression elicited by PPD and by trains of 3-10 pulses to an 11-pulse LFD protocol in persons with incomplete SCI. The amount of depression produced by PPD was less than an 11-pulse train (mean difference = 0.137). When compared to the 11-pulse train, the 5-pulse train had a Pearson's correlation coefficient (R) of 0.905 and a coefficient of determination (R2) of 0.818. Therefore, a 5-pulse train for assessing LFD elicits modulation similar to the 11-pulse train and thus we recommend its use in lieu of longer trains.
Collapse
Affiliation(s)
- Charles J. Creech
- Crawford Research Institute, Shepherd Center, Atlanta, Georgia, United States of America
- Program in Applied Physiology, Georgia Institute of Technology, School of Biological Sciences, Atlanta, Georgia, United States of America
| | - Jasmine M. Hope
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Anastasia Zarkou
- Crawford Research Institute, Shepherd Center, Atlanta, Georgia, United States of America
| | - Edelle C. Field-Fote
- Crawford Research Institute, Shepherd Center, Atlanta, Georgia, United States of America
- Program in Applied Physiology, Georgia Institute of Technology, School of Biological Sciences, Atlanta, Georgia, United States of America
- Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| |
Collapse
|
2
|
Alvarado-Navarrete MDC, Pliego-Carrillo AC, Ledesma-Ramírez CI, Cuellar CA. Post-activation depression of the Hoffman reflex is not altered by galvanic vestibular stimulation in healthy subjects. Front Integr Neurosci 2023; 17:1234613. [PMID: 37711909 PMCID: PMC10499171 DOI: 10.3389/fnint.2023.1234613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/08/2023] [Indexed: 09/16/2023] Open
Abstract
The comprehension of the neural elements interacting in the spinal cord affected by vestibular input will contribute to the understanding of movement execution in normal and pathological conditions. In this context, Hoffman's reflex (H-reflex) has been used to evaluate transient excitability changes on the spinal cord descending pathways. The post-activation depression (P-AD) of the H-reflex consists of evoking consecutive responses (>1 Hz) provoking an amplitude depression, which has been shown to diminish in pathological conditions (i.e., spasticity, diabetic neuropathy). Galvanic Vestibular Stimulation (GVS) is a non-invasive method that activates the vestibular afferents and has been used to study the excitability of the H-reflex applied as a conditioning pulse. To our knowledge, there are no reports evaluating the P-AD during and after GVS. Our primary aim was to determine if GVS alters the P-AD evoked by stimulating the tibial nerve at 0.1, 1, 5, and 10 Hz, recording in the gastrocnemius and soleus muscles. Direct current stimulation of 2.0 ± 0.6 mA with the cathode ipsilateral (Ipsi) or contralateral (Contra) to the H-reflex electrode montage was applied bilaterally over the mastoid process in 19 healthy subjects. The P-AD's immediate post-GVS response (P Ipsi, P Contra) was also analyzed. Secondarily, we analyzed the excitability of the H-reflex during GVS. Responses evoked at 0.1 Hz with GVS, post-GVS, and a Control (no GVS) condition were used for comparisons. Our results show that P-AD persisted in all subjects despite increased excitability induced by GVS: statistical significance was found when comparing P-AD at 1, 5, and 10 Hz with the corresponding condition (Control, Ipsi, P Ipsi, Contra, P Contra) at 0.1 Hz (p < 0.001). Additionally, the increase in excitability produced by GVS was quantified for the first H-reflex of each P-AD stimulation frequency. The percentage change for all GVS conditions surpassed the Control by at least 20%, being statistically significant for Contra compared to Control (p < 0.01). In summary, although GVS increases the excitability of the vestibulospinal pathway at a premotor level, the neural inhibitory mechanism present in P-AD remains unaltered in healthy subjects.
Collapse
Affiliation(s)
| | - Adriana C. Pliego-Carrillo
- Biomedical Engineering, School of Medicine, Autonomous University of the State of Mexico, Toluca, Mexico
| | | | - Carlos A. Cuellar
- School of Sport Sciences, Universidad Anáhuac México, Huixquilucan, Mexico
| |
Collapse
|
3
|
León F, Manzo L, Kababie R, Figueroa J, Cuellar C, Herrero P. Effects of Dry Needling on Spasticity in Multiple Sclerosis Evaluated Through the Rate-Dependent Depression of the H Reflex: A Case Report. Int Med Case Rep J 2023; 16:293-302. [PMID: 37223109 PMCID: PMC10202111 DOI: 10.2147/imcrj.s391201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 12/20/2022] [Indexed: 05/25/2023] Open
Abstract
Background Spasticity is a common symptom of multiple sclerosis (MS) which affects mobility. Dry Needling (DN) has shown a reduction in spasticity in neuromuscular conditions such as stroke and spinal cord injury although the mechanism of action is still unclear. In spastic individuals, the Rate-Dependent Depression (RDD) of the H reflex is decreased as compared to controls and analyzing the effects of DN in the RDD may help to understand its mechanism of action. Objective To evaluate the effect of Dry Needling on spasticity measured by the Rate-dependent Depression (RDD) of the H reflex in an MS patient. Methods Three time points were evaluated: Pre-intervention (T1), Post-intervention assessments were carried out in the seventh week at two-time points: Before DN (T2) and After DN (T3). Main outcomes included the RDD and latency of the H reflex in the lower limbs at stimulation frequencies of 0.1, 1, 2, and 5 Hz in a five consecutive pulses protocol. Results An impairment of the RDD of the H reflex at frequencies ≥1 Hz was found. Statistically significant differences were found when comparing the mean RDD of the H reflex in Pre-intervention compared to Post-intervention at 1, 2, and 5 Hz stimulation frequencies. Mean latencies were statistically lower when comparing Pre- vs Post-intervention. Conclusion Results suggest a partial reduction in spasticity represented by decrease of the excitability of the neural elements involved in the RDD of the H reflex following DN. The RDD of the H reflex could be implemented as an objective tool to monitor changes in spasticity in larger DN trials.
Collapse
Affiliation(s)
- Felix León
- Centro de Investigación en Ciencias de la Salud (CICSA), FCS, Universidad Anáhuac México, Campus Norte, Huixquilucan, Estado de México, México
| | - Leticia Manzo
- Centro de Investigación en Ciencias de la Salud (CICSA), FCS, Universidad Anáhuac México, Campus Norte, Huixquilucan, Estado de México, México
| | - Rebeca Kababie
- Centro de Investigación en Ciencias de la Salud (CICSA), FCS, Universidad Anáhuac México, Campus Norte, Huixquilucan, Estado de México, México
| | - Jimena Figueroa
- Centro de Investigación en Ciencias de la Salud (CICSA), FCS, Universidad Anáhuac México, Campus Norte, Huixquilucan, Estado de México, México
| | - Carlos Cuellar
- School of Sport Sciences, Universidad Anáhuac México, Campus Norte, Huixquilucan, Estado de México, México
| | - Pablo Herrero
- IIS Aragon, University of Zaragoza, Department of Physiatry and Nursing, Faculty of Health Sciences, Zaragoza, CP 50009, Spain
| |
Collapse
|
4
|
Skiadopoulos A, Pulverenti TS, Knikou M. Physiological effects of cathodal electrode configuration for transspinal stimulation in humans. J Neurophysiol 2022; 128:1663-1682. [PMID: 36416443 PMCID: PMC9762966 DOI: 10.1152/jn.00342.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/24/2022] Open
Abstract
Transspinal stimulation modulates neuronal excitability and promotes recovery in upper motoneuron lesions. The recruitment input-output curves of transspinal evoked potentials (TEPs) recorded from knee and ankle muscles, and their susceptibility to spinal inhibition, were recorded when the position, size, and number of the cathode electrode were arranged in four settings or protocols (Ps). The four Ps were the following: 1) one rectangular electrode placed at midline (KNIKOU-LAB4Recovery or K-LAB4Recovery; P-KLAB), 2) one square electrode placed at midline (P-2), 3) two square electrodes 1 cm apart placed at midline (P-3), and 4) one square electrode placed on each paravertebral side (P-4). P-KLAB and P-3 required less current to reach TEP threshold or maximal amplitudes. A rightward shift in TEP recruitment curves was evident for P-4, whereas the slope was increased for P-2 and P-4 compared with P-KLAB and P-3. TEP depression upon single and paired transspinal stimuli was pronounced in ankle TEPs but was less prominent in knee TEPs. TEP depression induced by single transspinal stimuli at 1.0 Hz was similar for most TEPs across protocols, but TEP depression induced by paired transspinal stimuli was different between protocols and was replaced by facilitation at 100-ms interstimulus interval for P-4. Our results suggest that P-KLAB and P-3 are preferred based on excitability threshold of motoneurons. P-KLAB produced more TEP depression, thereby maximizing the engagement of spinal neuronal pathways. We recommend P-KLAB to study neurophysiological mechanisms underlying transspinal stimulation or when used as a neuromodulation method for recovery in neurological disorders.NEW & NOTEWORTHY Transspinal stimulation with a rectangular cathode electrode (P-KLAB) requires less current to produce transspinal evoked potentials and maximizes spinal inhibition. We recommend P-KLAB for neurophysiological studies or when used as a neuromodulation method to enhance motor output and normalize muscle tone in neurological disorders.
Collapse
Affiliation(s)
- Andreas Skiadopoulos
- Klab4Recovery Research Program, The City University of New York, New York, New York
| | - Timothy S Pulverenti
- Klab4Recovery Research Program, The City University of New York, New York, New York
| | - Maria Knikou
- Klab4Recovery Research Program, The City University of New York, New York, New York
- Department of Physical Therapy, College of Staten Island, The City University of New York, Staten Island, New York
- PhD Program in Biology and Collaborative Neuroscience Program, Graduate Center of The City University of New York and College of Staten Island, Staten Island, New York
| |
Collapse
|
5
|
Zhou X, Zhu Y, Wang Z, Lin Z, Zhu D, Xie C, Calcutt NA, Guan Y. Rate-Dependent Depression: A Predictor of the Therapeutic Efficacy in Treating Painful Diabetic Peripheral Neuropathy. Diabetes 2022; 71:1272-1281. [PMID: 35234842 DOI: 10.2337/db21-0960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/24/2022] [Indexed: 11/13/2022]
Abstract
We investigated the application of rate-dependent depression (RDD) of the Hoffmann (H) wave as a predictor of treatment efficacy in patients with painful diabetic peripheral neuropathy (DPN). General medical information, scales, and nerve conduction data were collected from 73 healthy subjects, 50 subjects with type 2 diabetes and painless DPN, and 71 subjects with type 2 diabetes and painful DPN. The left tibial nerve was stimulated, and RDD was calculated by the decline in amplitude of the third H wave relative to the first one. Gabapentin treatment was initiated after baseline evaluation, and the RDD and visual analog scale (VAS) score were both evaluated regularly during the 2-week study period. At baseline, the painful DPN group exhibited significant RDD impairment across all stimulation frequencies. Gabapentin treatment significantly reduced the VAS score and restored RDD during the 2-week observation period. RDD was found to be an independent factor of minimal VAS score improvement, such that the benefit increased by 1.27 times per 1% decrease in the RDD value. In conclusion, this study demonstrates that diabetes-induced loss of RDD can be modified by gabapentin and suggests that RDD may be valuable for predicting the initial efficacy of gabapentin therapy in patients with painful DPN.
Collapse
Affiliation(s)
- Xiajun Zhou
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Ying Zhu
- Department of Neurology, Shanghai International Medical Center, Shanghai, China
| | - Ze Wang
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhi Lin
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Desheng Zhu
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Chong Xie
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, San Diego, CA
| | - Yangtai Guan
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| |
Collapse
|
6
|
Zhou X, Wang Z, Lin Z, Zhu Y, Zhu D, Xie C, Calcutt NA, Guan Y. Rate-dependent depression is impaired in amyotrophic lateral sclerosis. Neurol Sci 2021; 43:1831-1838. [PMID: 34518934 DOI: 10.1007/s10072-021-05596-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/06/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE We investigated rate-dependent depression (RDD) of the Hoffman reflex (H-reflex) in patients with amyotrophic lateral sclerosis (ALS), a degenerative disease with ventral horn involvement. PATIENTS AND METHODS In this case-control study, we enrolled 27 patients with ALS and 30 matched healthy control subjects. Clinical and electrophysiological assessments, as well as RDD in response to various stimulation frequencies (0.5 Hz, 1 Hz, 3 Hz and 5 Hz), were compared between groups. Multiple clinical and electrophysiological factors were also explored to determine any underlying associations with RDD. RESULTS The ALS group showed a significant loss of RDD across all frequencies compared to the control group, most notably following 1 Hz stimulation (19.1 ± 20.3 vs. 34.0 ± 13.7%, p = 0.003). Among factors that might influence RDD, the enlargement of the motor unit potential (MUP) showed a significant relationship with RDD following multifactor analysis of variance (p = 0.007) and Pearson correlation analysis (ρ = - 0.70, p < 0.001), while various upper motor neuron manifestations were not correlated with RDD values (p > 0.05). CONCLUSION We report a loss of RDD in patients with ALS. The strong correlation detected between the RDD deficit and increased MUP suggests that RDD is a sensitive indicator of underlying spinal disinhibition in ALS. TRIAL REGISTRATION ChiCTR2000038848, 10/7/2020 (retrospectively registered), http://www.chictr.org.cn/ .
Collapse
Affiliation(s)
- Xiajun Zhou
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, 160 Pujian Road, Pudong, Shanghai, 200127, China
| | - Ze Wang
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, 160 Pujian Road, Pudong, Shanghai, 200127, China
| | - Zhi Lin
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, 160 Pujian Road, Pudong, Shanghai, 200127, China
| | - Ying Zhu
- Department of Neurology, Shanghai International Medical Center, Shanghai, 201318, China
| | - Desheng Zhu
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, 160 Pujian Road, Pudong, Shanghai, 200127, China
| | - Chong Xie
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, 160 Pujian Road, Pudong, Shanghai, 200127, China
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, San Diego, CA, 92093, USA
| | - Yangtai Guan
- Department of Neurology, Renji Hospital, Shanghai Jiaotong University School of Medicine, 160 Pujian Road, Pudong, Shanghai, 200127, China.
| |
Collapse
|
7
|
Worthington A, Kalteniece A, Ferdousi M, D'Onofrio L, Dhage S, Azmi S, Adamson C, Hamdy S, Malik RA, Calcutt NA, Marshall AG. Spinal Inhibitory Dysfunction in Patients With Painful or Painless Diabetic Neuropathy. Diabetes Care 2021; 44:1835-1841. [PMID: 34385346 DOI: 10.2337/dc20-2797] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 05/13/2021] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Impaired rate-dependent depression of the Hoffman reflex (HRDD) is a marker of spinal inhibitory dysfunction and has previously been associated with painful neuropathy in a proof-of-concept study in patients with type 1 diabetes. We have now undertaken an assessment of HRDD in patients with type 1 or type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 148 participants, including 34 healthy control subjects, 42 patients with painful diabetic neuropathy, and 62 patients with diabetic neuropathy without pain, underwent an assessment of HRDD and a detailed assessment of peripheral neuropathy, including nerve conduction studies, corneal confocal microscopy, and thermal threshold testing. RESULTS Compared with healthy control subjects (P < 0.001) and patients without pain (P < 0.001), we found that HRDD is impaired in patients with type 1 or type 2 diabetes with neuropathic pain. These impairments are unrelated to diabetes type and the presence or severity of neuropathy. In contrast, patients without neuropathic pain (P < 0.05) exhibited enhanced HRDD compared with control subjects. CONCLUSIONS We suggest that loss or impairment of HRDD may help to identify a subpopulation of patients with painful diabetic neuropathy mediated by impaired spinal inhibitory systems who may respond optimally to therapies that target spinal or supraspinal mechanisms. Enhanced RDD in patients without pain may reflect engagement of spinal pain-suppressing mechanisms.
Collapse
Affiliation(s)
- Anne Worthington
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Alise Kalteniece
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Maryam Ferdousi
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Luca D'Onofrio
- Department of Experimental Medicine, Sapienza University, Rome, Italy
| | - Shaishav Dhage
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Shazli Azmi
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K.,Diabetes Centre, Manchester University NHS Foundation Trust, Manchester, U.K
| | - Clare Adamson
- Diabetes Centre, Manchester University NHS Foundation Trust, Manchester, U.K
| | - Shaheen Hamdy
- Centre for Gastrointestinal Sciences, Division of Diabetes and Endocrinology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Rayaz A Malik
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K.,Weill Cornell Medicine-Qatar, Research Division, Qatar Foundation, Education City
| | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Andrew G Marshall
- Division of Neuroscience and Experimental Psychology, Faculty of Medical and Human Sciences, University of Manchester, Manchester, U.K. .,Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, U.K
| |
Collapse
|
8
|
Worthington A, Kalteniece A, Ferdousi M, D’Onofrio L, Dhage S, Azmi S, Adamson C, Hamdy S, Malik RA, Calcutt NA, Marshall AG. Optimal Utility of H-Reflex RDD as a Biomarker of Spinal Disinhibition in Painful and Painless Diabetic Neuropathy. Diagnostics (Basel) 2021; 11:1247. [PMID: 34359330 PMCID: PMC8306975 DOI: 10.3390/diagnostics11071247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/27/2021] [Accepted: 07/07/2021] [Indexed: 11/20/2022] Open
Abstract
Impaired rate-dependent depression of the Hoffman reflex (HRDD) is a potential biomarker of impaired spinal inhibition in patients with painful diabetic neuropathy. However, the optimum stimulus-response parameters that identify patients with spinal disinhibition are currently unknown. We systematically compared HRDD, performed using trains of 10 stimuli at five stimulation frequencies (0.3, 0.5, 1, 2 and 3 Hz), in 42 subjects with painful and 62 subjects with painless diabetic neuropathy with comparable neuropathy severity, and 34 healthy controls. HRDD was calculated using individual and mean responses compared to the initial response. At stimulation frequencies of 1, 2 and 3 Hz, HRDD was significantly impaired in patients with painful diabetic neuropathy compared to patients with painless diabetic neuropathy for all parameters and for most parameters when compared to healthy controls. HRDD was significantly enhanced in patients with painless diabetic neuropathy compared to controls for responses towards the end of the 1 Hz stimulation train. Receiver operating characteristic curve analysis in patients with and without pain showed that the area under the curve was greatest for response averages of stimuli 2-4 and 2-5 at 1 Hz, AUC = 0.84 (95%CI 0.76-0.92). Trains of 5 stimuli delivered at 1 Hz can segregate patients with painful diabetic neuropathy and spinal disinhibition, whereas longer stimulus trains are required to segregate patients with painless diabetic neuropathy and enhanced spinal inhibition.
Collapse
Affiliation(s)
- Anne Worthington
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.W.); (S.H.)
| | - Alise Kalteniece
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.K.); (M.F.); (S.D.); (S.A.); (R.A.M.)
| | - Maryam Ferdousi
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.K.); (M.F.); (S.D.); (S.A.); (R.A.M.)
| | - Luca D’Onofrio
- Department of Experimental Medicine, Sapienza University, 00185 Rome, Italy;
| | - Shaishav Dhage
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.K.); (M.F.); (S.D.); (S.A.); (R.A.M.)
| | - Shazli Azmi
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.K.); (M.F.); (S.D.); (S.A.); (R.A.M.)
- Diabetes Centre, Manchester University NHS Foundation Trust, Manchester M13 0JE, UK;
| | - Clare Adamson
- Diabetes Centre, Manchester University NHS Foundation Trust, Manchester M13 0JE, UK;
| | - Shaheen Hamdy
- Division of Diabetes, Endocrinology and Gastroenterology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.W.); (S.H.)
| | - Rayaz A. Malik
- Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK; (A.K.); (M.F.); (S.D.); (S.A.); (R.A.M.)
- Weill Cornell Medicine-Qatar, Research Division, Qatar Foundation, Education City, Doha 24144, Qatar
| | - Nigel A. Calcutt
- Department of Pathology, University of California, San Diego, CA 92093-0612, USA;
| | - Andrew G. Marshall
- Division of Neuroscience and Experimental Psychology, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9PL, UK
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L69 3BX, UK
| |
Collapse
|
9
|
Marshall A, Alam U, Themistocleous A, Calcutt N, Marshall A. Novel and Emerging Electrophysiological Biomarkers of Diabetic Neuropathy and Painful Diabetic Neuropathy. Clin Ther 2021; 43:1441-1456. [PMID: 33906790 DOI: 10.1016/j.clinthera.2021.03.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 12/14/2022]
Abstract
PURPOSE Diabetic peripheral neuropathy (DPN) is the most common complication of diabetes. Small and large peripheral nerve fibers can be involved in DPN. Large nerve fiber damage causes paresthesia, sensory loss, and muscle weakness, and small nerve fiber damage is associated with pain, anesthesia, foot ulcer, and autonomic symptoms. Treatments for DPN and painful DPN (pDPN) pose considerable challenges due to the lack of effective therapies. To meet these challenges, there is a major need to develop biomarkers that can reliably diagnose and monitor progression of nerve damage and, for pDPN, facilitate personalized treatment based on underlying pain mechanisms. METHODS This study involved a comprehensive literature review, incorporating article searches in electronic databases (Google Scholar, PubMed, and OVID) and reference lists of relevant articles with the authors' substantial expertise in DPN. This review considered seminal and novel research and summarizes emerging biomarkers of DPN and pDPN that are based on neurophysiological methods. FINDINGS From the evidence gathered from 145 papers, this submission describes emerging clinical neurophysiological methods with potential to act as biomarkers for the diagnosis and monitoring of DPN as well as putative future roles as predictors of response to antineuropathic pain medication in pDPN. Nerve conduction studies only detect large fiber damage and do not capture pathology or dysfunction of small fibers. Because small nerve fiber damage is prominent in DPN, additional biomarkers of small nerve fiber function are needed. Activation of peripheral nociceptor fibers using laser, heat, or targeted electrical stimuli can generate pain-related evoked potentials, which are an objective neurophysiological measure of damage along the small fiber pathways. Assessment of nerve excitability, which provides a surrogate of axonal properties, may detect alterations in function before abnormalities are detected by nerve conduction studies. Microneurography and rate-dependent depression of the Hoffmann-reflex can be used to dissect underlying pain-generating mechanisms arising from the periphery and spinal cord, respectively. Their role in informing mechanistic-based treatment of pDPN as well as facilitating clinical trials design is discussed. IMPLICATIONS The neurophysiological methods discussed, although currently not practical for use in busy outpatient settings, detect small fiber and early large fiber damage in DPN as well as disclosing dominant pain mechanisms in pDPN. They are suited as diagnostic and predictive biomarkers as well as end points in mechanistic clinical trials of DPN and pDPN.
Collapse
Affiliation(s)
- Anne Marshall
- Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom; Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Uazman Alam
- Division of Diabetes, Endocrinology and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom; Cardiovascular and Metabolic Medicine, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Andreas Themistocleous
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom; Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nigel Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, California
| | - Andrew Marshall
- Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom; Department of Clinical Neurophysiology, The Walton Centre, Liverpool, United Kingdom; Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.
| |
Collapse
|
10
|
Gong C, Zheng X, Guo F, Wang Y, Zhang S, Chen J, Sun X, Shah SZA, Zheng Y, Li X, Yin Y, Li Q, Huang X, Guo T, Han X, Zhang SC, Wang W, Chen H. Human spinal GABA neurons alleviate spasticity and improve locomotion in rats with spinal cord injury. Cell Rep 2021; 34:108889. [PMID: 33761348 DOI: 10.1016/j.celrep.2021.108889] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/21/2020] [Accepted: 03/01/2021] [Indexed: 01/10/2023] Open
Abstract
Spinal cord injury (SCI) often results in spasticity. There is currently no effective therapy for spasticity. Here, we describe a method to efficiently differentiate human pluripotent stem cells from spinal GABA neurons. After transplantation into the injured rat spinal cord, the DREADD (designer receptors exclusively activated by designer drug)-expressing spinal progenitors differentiate into GABA neurons, mitigating spasticity-like response of the rat hindlimbs and locomotion deficits in 3 months. Administering clozapine-N-oxide, which activates the grafted GABA neurons, further alleviates spasticity-like response, suggesting an integration of grafted GABA neurons into the local neural circuit. These results highlight the therapeutic potential of the spinal GABA neurons for SCI.
Collapse
Affiliation(s)
- ChenZi Gong
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xiaolong Zheng
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - FangLiang Guo
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - YaNan Wang
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Song Zhang
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jing Chen
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - XueJiao Sun
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Sayed Zulfiqar Ali Shah
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - YiFeng Zheng
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xiao Li
- School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Yatao Yin
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qian Li
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - XiaoLin Huang
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Tiecheng Guo
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xiaohua Han
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Su-Chun Zhang
- Waisman Center, Department of Neuroscience and Department of Neurology, University of Wisconsin, Madison, WI, USA; Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Wei Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
| | - Hong Chen
- Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
| |
Collapse
|
11
|
Lee-Kubli CA, Zhou X, Jolivalt CG, Calcutt NA. Pharmacological Modulation of Rate-Dependent Depression of the Spinal H-Reflex Predicts Therapeutic Efficacy against Painful Diabetic Neuropathy. Diagnostics (Basel) 2021; 11:diagnostics11020283. [PMID: 33670344 PMCID: PMC7917809 DOI: 10.3390/diagnostics11020283] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/22/2022] Open
Abstract
Impaired rate-dependent depression (RDD) of the spinal H-reflex occurs in diabetic rodents and a sub-set of patients with painful diabetic neuropathy. RDD is unaffected in animal models of painful neuropathy associated with peripheral pain mechanisms and diabetic patients with painless neuropathy, suggesting RDD could serve as a biomarker for individuals in whom spinal disinhibition contributes to painful neuropathy and help identify therapies that target impaired spinal inhibitory function. The spinal pharmacology of RDD was investigated in normal rats and rats after 4 and 8 weeks of streptozotocin-induced diabetes. In normal rats, dependence of RDD on spinal GABAergic inhibitory function encompassed both GABAA and GABAB receptor sub-types. The time-dependent emergence of impaired RDD in diabetic rats was preceded by depletion of potassium-chloride co-transporter 2 (KCC2) protein in the dorsal, but not ventral, spinal cord and by dysfunction of GABAA receptor-mediated inhibition. GABAB receptor-mediated spinal inhibition remained functional and initially compensated for loss of GABAA receptor-mediated inhibition. Administration of the GABAB receptor agonist baclofen restored RDD and alleviated indices of neuropathic pain in diabetic rats, as did spinal delivery of the carbonic anhydrase inhibitor acetazolamide. Pharmacological manipulation of RDD can be used to identify potential therapies that act against neuropathic pain arising from spinal disinhibition.
Collapse
|
12
|
Jin HY, Moon SS, Calcutt NA. Lost in Translation? Measuring Diabetic Neuropathy in Humans and Animals. Diabetes Metab J 2021; 45:27-42. [PMID: 33307618 PMCID: PMC7850880 DOI: 10.4093/dmj.2020.0216] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022] Open
Abstract
The worldwide diabetes epidemic is estimated to currently afflict almost 500 million persons. Long-term diabetes damages multiple organ systems with the blood vessels, eyes, kidneys and nervous systems being particularly vulnerable. These complications of diabetes reduce lifespan, impede quality of life and impose a huge social and economic burden on both the individual and society. Peripheral neuropathy is a debilitating complication that will impact over half of all persons with diabetes. There is no treatment for diabetic neuropathy and a disturbingly long history of therapeutic approaches showing promise in preclinical studies but failing to translate to the clinic. These failures have prompted re-examination of both the animal models and clinical trial design. This review focuses on the functional and structural parameters used as indices of peripheral neuropathy in preclinical and clinical studies and the extent to which they share a common pathogenesis and presentation. Nerve conduction studies in large myelinated fibers have long been the mainstay of preclinical efficacy screening programs and clinical trials, supplemented by quantitative sensory tests. However, a more refined approach is emerging that incorporates measures of small fiber density in the skin and cornea alongside these traditional assays at both preclinical and clinical phases.
Collapse
Affiliation(s)
- Heung Yong Jin
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jeonbuk National University Medical School, Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju,
USA
| | - Seong-Su Moon
- Department of Internal Medicine, Dongguk University College of Medicine, Gyeongju,
USA
- Division of Endocrinology, Department of Internal Medicine, Nazareth General Hospital, Daegu,
Korea,
USA
| | - Nigel A. Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA,
USA
| |
Collapse
|
13
|
Amyotrophic lateral sclerosis weakens spinal recurrent inhibition and post-activation depression. Clin Neurophysiol 2020; 131:2875-2886. [DOI: 10.1016/j.clinph.2020.09.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 08/15/2020] [Accepted: 09/07/2020] [Indexed: 01/07/2023]
|
14
|
Özyurt MG, Topkara B, Şenocak BS, Budan AS, Yüce MN, Türker KS. Post-activation depression of primary afferents reevaluated in humans. J Electromyogr Kinesiol 2020; 54:102460. [PMID: 32905963 DOI: 10.1016/j.jelekin.2020.102460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/05/2020] [Accepted: 08/19/2020] [Indexed: 11/26/2022] Open
Abstract
Amplitude variation of Hoffmann Reflex (H-reflex) was used as a tool to investigate many neuronal networks. However, H-reflex itself is a subject to intrinsic changes including post-activation depression (P-AD). We aimed to investigate P-AD and its implication on motor control in humans. Upon tibial nerve stimulation in 23 healthy participants, peak-to-peak amplitude change of H-reflex was investigated using surface electromyography (SEMG) of soleus muscle. Variety of stimulus intensities, interstimulus intervals (ISIs), voluntary contraction levels/types and force recording were used to investigate the nature of P-AD. We have shown that P-AD was significantly stronger in the shorter ISIs. The only exception was the ISI of 200 msecs which had a weaker P-AD than some of the longer ISIs. Sudden muscle relaxation, on the other hand, further increased the effectiveness of the ongoing P-AD. Moreover, P-AD displayed its full effect with the first stimulus when there was no muscle contraction and was efficient to reduce the muscle force output by about 30%. These findings provide insight about the variations and mechanism of P-AD and could lead to improvements in diagnostic tools in neurological diseases.
Collapse
Affiliation(s)
| | - Betilay Topkara
- Koç University, School of Medicine, 34450 Sariyer, Istanbul, Turkey
| | | | | | | | | |
Collapse
|
15
|
Novel human models for elucidating mechanisms of rate-sensitive H-reflex depression. Biomed J 2020; 43:44-52. [PMID: 32200955 PMCID: PMC7090317 DOI: 10.1016/j.bj.2019.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 01/24/2019] [Accepted: 07/10/2019] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND This study used novel human neurophysiologic models to investigate whether the mechanism of rate-sensitive H-reflex depression lies in the pre-synaptic or post-synaptic locus in humans. We hypothesized that pre-synaptic inhibition would suppress Ia afferents and H-reflexes without suppressing alpha motor neurons or motor evoked potentials (MEPs). In contrast, post-synaptic inhibition would suppress alpha motor neurons, thereby reducing H-reflexes and MEPs. METHODS We recruited 23 healthy adults with typical rate-sensitive H-reflex depression, 2 participants with acute sensory-impaired spinal cord injury (SCI) (to rule out influence of sensory stimulation on supra-spinal excitability), and an atypical cohort of 5 healthy adults without rate-sensitive depression. After a single electrical stimulation to the tibial nerve, we administered either a testing H-reflex or a testing MEP at 50-5000 ms intervals. RESULTS Testing MEPs were not diminished in healthy subjects with or without typical rate-sensitive H-reflex depression, or in subjects with sensory-impaired SCI. MEP responses were similar in healthy subjects with versus without rate-sensitive H-reflex depression. CONCLUSIONS Results from these novel in vivo human models support a pre-synaptic locus of rate-sensitive H-reflex depression for the first time in humans. Spinal reflex excitability can be modulated separately from descending corticospinal influence. Each represents a potential target for neuromodulatory intervention.
Collapse
|
16
|
Hofstoetter US, Freundl B, Binder H, Minassian K. Recovery cycles of posterior root-muscle reflexes evoked by transcutaneous spinal cord stimulation and of the H reflex in individuals with intact and injured spinal cord. PLoS One 2019; 14:e0227057. [PMID: 31877192 PMCID: PMC6932776 DOI: 10.1371/journal.pone.0227057] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 12/10/2019] [Indexed: 11/18/2022] Open
Abstract
Posterior root-muscle (PRM) reflexes are short-latency spinal reflexes evoked by epidural or transcutaneous spinal cord stimulation (SCS) in clinical and physiological studies. PRM reflexes share key physiological characteristics with the H reflex elicited by electrical stimulation of large-diameter muscle spindle afferents in the tibial nerve. Here, we compared the H reflex and the PRM reflex of soleus in response to transcutaneous stimulation by studying their recovery cycles in ten neurologically intact volunteers and ten individuals with traumatic, chronic spinal cord injury (SCI). The recovery cycles of the reflexes, i.e., the time course of their excitability changes, were assessed by paired pulses with conditioning-test intervals of 20–5000 ms. Between the subject groups, no statistical difference was found for the recovery cycles of the H reflexes, yet those of the PRM reflexes differed significantly, with a striking suppression in the intact group. When comparing the reflex types, they did not differ in the SCI group, while the PRM reflexes were more strongly depressed in the intact group for durations characteristic for presynaptic inhibition. These differences may arise from the concomitant stimulation of several posterior roots containing afferent fibers of various lower extremity nerves by transcutaneous SCS, producing multi-source heteronymous presynaptic inhibition, and the collective dysfunction of inhibitory mechanisms after SCI contributing to spasticity. PRM-reflex recovery cycles additionally obtained for bilateral rectus femoris, biceps femoris, tibialis anterior, and soleus all demonstrated a stronger suppression in the intact group. Within both subject groups, the thigh muscles showed a stronger recovery than the lower leg muscles, which may reflect a characteristic difference in motor control of diverse muscles. Based on the substantial difference between intact and SCI individuals, PRM-reflex depression tested with paired pulses could become a sensitive measure for spasticity and motor recovery.
Collapse
Affiliation(s)
- Ursula S. Hofstoetter
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
- * E-mail:
| | - Brigitta Freundl
- Neurological Center, Maria Theresien Schloessel, Otto Wagner Hospital, Vienna, Austria
| | - Heinrich Binder
- Neurological Center, Maria Theresien Schloessel, Otto Wagner Hospital, Vienna, Austria
| | - Karen Minassian
- Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria
| |
Collapse
|
17
|
Liang JN, Lee YJ, Akoopie E, Kleven BC, Koch T, Ho KY. Impaired H-Reflex Adaptations Following Slope Walking in Individuals With Post-stroke Hemiparesis. Front Physiol 2019; 10:1232. [PMID: 31632287 PMCID: PMC6779794 DOI: 10.3389/fphys.2019.01232] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 09/09/2019] [Indexed: 01/14/2023] Open
Abstract
Background and Purpose Short term adaptations in the Ia afferent-motoneuron pathway, as measured using the H-reflex, in response to altered ground reaction forces (GRFs) applied at the feet during slope walking have been observed in the non-impaired nervous system. The ability of the stroke-impaired nervous system to adapt to altered GRFs have not been examined. The purpose of this study was to examine the acute effects of altered propulsive and braking forces applied at the feet, which naturally occurs when walking on different slopes, on adaptations of the H-reflex pathway in individuals with chronic post-stroke hemiparesis. Methods Twelve individuals chronically post-stroke and 10 age-similar non-neurologically impaired controls walked on an instrumented treadmill for 20 min under level, upslope and downslope conditions. GRFs were measured during walking and soleus H-reflexes were recorded prior to and immediately after walking. A 3 (limbs: paretic, non-paretic, and non-impaired) × 3 (slope: level, upslope, downslope) mixed factorial ANOVA was conducted on the propulsive and braking forces. A 2 (limb: paretic and non-impaired) × 2 (time: pre and post) × 3 (slope: level, upslope, and downslope) mixed factorial ANOVA was conducted to assess the soleus H-reflex amplitudes. Results In both post-stroke and non-impaired groups, during downslope walking, peak propulsive forces decreased, while peak braking forces increased. In contrast, during upslope walking, peak propulsive forces increased and peak braking forces decreased. We observed reduced soleus H-reflex amplitudes immediately following 20 min of level, downslope and upslope walking in non-impaired individuals but not in the paretic legs of individuals with chronic post-stroke hemiparesis. Discussion and Conclusion Similar pattern of change in peak propulsive and braking forces with respect to different slopes was observed in both individuals post-stroke and non-impaired individuals, but the magnitude of GRFs were smaller in individuals post-stroke due to the slower walking speed. Our results suggested that impaired modulation of the H-reflex pathway potentially underlies the lack of neuroadaptations in individuals with chronic post-stroke hemiparesis.
Collapse
Affiliation(s)
- Jing Nong Liang
- Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Yun-Ju Lee
- Department of Industrial Engineering and Engineering Management, National Tsing Hua University, Hsinchu, Taiwan
| | - Eric Akoopie
- Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Brooke Conway Kleven
- Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Trisha Koch
- Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Kai-Yu Ho
- Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, NV, United States
| |
Collapse
|
18
|
Mekhael W, Begum S, Samaddar S, Hassan M, Toruno P, Ahmed M, Gorin A, Maisano M, Ayad M, Ahmed Z. Repeated anodal trans-spinal direct current stimulation results in long-term reduction of spasticity in mice with spinal cord injury. J Physiol 2019; 597:2201-2223. [PMID: 30689208 PMCID: PMC6462463 DOI: 10.1113/jp276952] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 01/18/2019] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Spasticity is a disorder of muscle tone that is associated with lesions of the motor system. This condition involves an overactive spinal reflex loop that resists the passive lengthening of muscles. Previously, we established that application of anodal trans-spinal direct current stimulation (a-tsDCS) for short periods of time to anaesthetized mice sustaining a spinal cord injury leads to an instantaneous reduction of spasticity. However, the long-term effects of repeated a-tsDCS and its mechanism of action remained unknown. In the present study, a-tsDCS was performed for 7 days and this was found to cause long-term reduction in spasticity, increased rate-dependent depression in spinal reflexes, and improved ground and skill locomotion. Pharmacological, molecular and cellular evidence further suggest that a novel mechanism involving Na-K-Cl cotransporter isoform 1 mediates the observed long-term effects of repeated a-tsDCS. ABSTRACT Spasticity can cause pain, fatigue and sleep disturbances; restrict daily activities such as walking, sitting and bathing; and complicate rehabilitation efforts. Thus, spasticity negatively influences an individual's quality of life and novel therapeutic interventions are needed. We previously demonstrated in anaesthetized mice that a short period of trans-spinal subthreshold direct current stimulation (tsDCS) reduces spasticity. In the present study, the long-term effects of repeated tsDCS to attenuate abnormal muscle tone in awake female mice with spinal cord injuries were investigated. A motorized system was used to test velocity-dependent ankle resistance and associated electromyographical activity. Analysis of ground and skill locomotion was also performed, with electrophysiological, molecular and cellular studies being conducted to reveal a potential underlying mechanism of action. A 4 week reduction in spasticity was associated with an increase in rate-dependent depression of spinal reflexes, and ground and skill locomotion were improved following 7 days of anodal-tsDCS (a-tsDCS). Secondary molecular, cellular and pharmacological experiments further demonstrated that the expression of K-Cl co-transporter isoform 2 (KCC2) was not changed in animals with spasticity. However, Na-K-Cl cotransporter isoform 1 (NKCC1) was significantly up-regulated in mice that exhibited spasticity. When mice were treated with a-tsDCS, down regulation of NKCC1 was detected, and this level did not significantly differ from that in the non-injured control mice. Thus, long lasting reduction of spasticity by a-tsDCS via downregulation of NKCC1 may constitute a novel therapy for spasticity following spinal cord injury.
Collapse
Affiliation(s)
- Wagdy Mekhael
- Graduate CenterCity University of New YorkNew YorkNYUSA
| | - Sultana Begum
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Sreyashi Samaddar
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
- Department of Physical TherapyThe College of Staten IslandStaten IslandNYUSA
| | - Mazen Hassan
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Pedro Toruno
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Malik Ahmed
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Alexis Gorin
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Michael Maisano
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Mark Ayad
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
| | - Zaghloul Ahmed
- Graduate CenterCity University of New YorkNew YorkNYUSA
- Center for Developmental NeuroscienceThe College of Staten IslandStaten IslandNYUSA
- Department of Physical TherapyThe College of Staten IslandStaten IslandNYUSA
| |
Collapse
|
19
|
Formento E, Minassian K, Wagner F, Mignardot JB, Le Goff-Mignardot CG, Rowald A, Bloch J, Micera S, Capogrosso M, Courtine G. Electrical spinal cord stimulation must preserve proprioception to enable locomotion in humans with spinal cord injury. Nat Neurosci 2018; 21:1728-1741. [PMID: 30382196 PMCID: PMC6268129 DOI: 10.1038/s41593-018-0262-6] [Citation(s) in RCA: 205] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 09/26/2018] [Indexed: 11/25/2022]
Abstract
Epidural electrical stimulation (EES) of the spinal cord restores locomotion in animal models of spinal cord injury but is less effective in humans. Here we hypothesized that this interspecies discrepancy is due to interference between EES and proprioceptive information in humans. Computational simulations and preclinical and clinical experiments reveal that EES blocks a significant amount of proprioceptive input in humans, but not in rats. This transient deafferentation prevents modulation of reciprocal inhibitory networks involved in locomotion and reduces or abolishes the conscious perception of leg position. Consequently, continuous EES can only facilitate locomotion within a narrow range of stimulation parameters and is unable to provide meaningful locomotor improvements in humans without rehabilitation. Simulations showed that burst stimulation and spatiotemporal stimulation profiles mitigate the cancellation of proprioceptive information, enabling robust control over motor neuron activity. This demonstrates the importance of stimulation protocols that preserve proprioceptive information to facilitate walking with EES.
Collapse
Affiliation(s)
- Emanuele Formento
- Bertarelli Foundation Chair in Translational NeuroEngineering, Institute of Bioengineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Karen Minassian
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Fabien Wagner
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Jean Baptiste Mignardot
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Camille G Le Goff-Mignardot
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
| | - Andreas Rowald
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
- Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg, Switzerland
| | - Jocelyne Bloch
- Department of Neurosurgery, University Hospital of Lausanne (CHUV), Lausanne, Switzerland
| | - Silvestro Micera
- Bertarelli Foundation Chair in Translational NeuroEngineering, Institute of Bioengineering, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland
- Neural Engineering Area, Institute of Biorobotics, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Marco Capogrosso
- Department of Medicine, Faculty of Sciences, University of Fribourg, Fribourg, Switzerland
| | - Gregoire Courtine
- Center for Neuroprosthetics and Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
- Department of Neurosurgery, University Hospital of Lausanne (CHUV), Lausanne, Switzerland.
| |
Collapse
|
20
|
Shiao R, Lee-Kubli CA. Neuropathic Pain After Spinal Cord Injury: Challenges and Research Perspectives. Neurotherapeutics 2018; 15:635-653. [PMID: 29736857 PMCID: PMC6095789 DOI: 10.1007/s13311-018-0633-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Neuropathic pain is a debilitating consequence of spinal cord injury (SCI) that remains difficult to treat because underlying mechanisms are not yet fully understood. In part, this is due to limitations of evaluating neuropathic pain in animal models in general, and SCI rodents in particular. Though pain in patients is primarily spontaneous, with relatively few patients experiencing evoked pains, animal models of SCI pain have primarily relied upon evoked withdrawals. Greater use of operant tasks for evaluation of the affective dimension of pain in rodents is needed, but these tests have their own limitations such that additional studies of the relationship between evoked withdrawals and operant outcomes are recommended. In preclinical SCI models, enhanced reflex withdrawal or pain responses can arise from pathological changes that occur at any point along the sensory neuraxis. Use of quantitative sensory testing for identification of optimal treatment approach may yield improved identification of treatment options and clinical trial design. Additionally, a better understanding of the differences between mechanisms contributing to at- versus below-level neuropathic pain and neuropathic pain versus spasticity may shed insights into novel treatment options. Finally, the role of patient characteristics such as age and sex in pathogenesis of neuropathic SCI pain remains to be addressed.
Collapse
Affiliation(s)
- Rani Shiao
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines, La Jolla, California, 92073, USA
| | - Corinne A Lee-Kubli
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines, La Jolla, California, 92073, USA.
| |
Collapse
|
21
|
Lee-Kubli C, Marshall AG, Malik RA, Calcutt NA. The H-Reflex as a Biomarker for Spinal Disinhibition in Painful Diabetic Neuropathy. Curr Diab Rep 2018; 18:1. [PMID: 29362940 PMCID: PMC6876556 DOI: 10.1007/s11892-018-0969-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE OF REVIEW Neuropathic pain may arise from multiple mechanisms and locations. Efficacy of current treatments for painful diabetic neuropathy is limited to an unpredictable subset of patients, possibly reflecting diversity of pain generator mechanisms, and there is a lack of targeted treatments for individual patients. This review summarizes preclinical evidence supporting a role for spinal disinhibition in painful diabetic neuropathy, the physiology and pharmacology of rate-dependent depression (RDD) of the spinal H-reflex and the translational potential of using RDD as a biomarker of spinally mediated pain. RECENT FINDINGS Impaired RDD occurs in animal models of diabetes and was also detected in diabetic patients with painful vs painless neuropathy. RDD status can be determined using standard neurophysiological equipment. Loss of RDD may provide a clinical biomarker of spinal disinhibition, thereby enabling a personalized medicine approach to selection of current treatment options and enrichment of future clinical trial populations.
Collapse
Affiliation(s)
| | - Andrew G Marshall
- Faculty of Medical and Human Sciences, Institute of Cardiovascular Sciences, University of Manchester and National Institute for Healthy Research/Wellcome Trust Clinical Research Facility, Manchester, UK
- Department of Clinical Neurophysiology, Salford Royal Hospital, National Health Service Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
| | - Rayaz A Malik
- Faculty of Medical and Human Sciences, Institute of Cardiovascular Sciences, University of Manchester and National Institute for Healthy Research/Wellcome Trust Clinical Research Facility, Manchester, UK
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA, USA.
| |
Collapse
|
22
|
Liabeuf S, Stuhl-Gourmand L, Gackière F, Mancuso R, Sanchez Brualla I, Marino P, Brocard F, Vinay L. Prochlorperazine Increases KCC2 Function and Reduces Spasticity after Spinal Cord Injury. J Neurotrauma 2017; 34:3397-3406. [PMID: 28747093 DOI: 10.1089/neu.2017.5152] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In mature neurons, low intracellular chloride level required for inhibition is maintained by the potassium-chloride cotransporter, KCC2. Impairment of Cl- extrusion after KCC2 dysfunction has been involved in many central nervous system disorders, such as seizures, neuropathic pain, or spasticity, after a spinal cord injury (SCI). This makes KCC2 an appealing drug target for restoring Cl- homeostasis and inhibition in pathological conditions. In the present study, we screen the Prestwick Chemical Library® and identify conventional antipsychotics phenothiazine derivatives as enhancers of KCC2 activity. Among them, prochlorperazine hyperpolarizes the Cl- equilibrium potential in motoneurons of neonatal rats and restores the reciprocal inhibition post-SCI. The compound alleviates spasticity in chronic adult SCI rats with an efficacy equivalent to the antispastic agent, baclofen, and rescues the SCI-induced downregulation of KCC2 in motoneurons below the lesion. These pre-clinical data support prochlorperazine for a new therapeutic indication in the treatment of spasticity post-SCI and neurological disorders involving a KCC2 dysfunction.
Collapse
Affiliation(s)
- Sylvie Liabeuf
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Laetitia Stuhl-Gourmand
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Florian Gackière
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Renzo Mancuso
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Irene Sanchez Brualla
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Philippe Marino
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Frédéric Brocard
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| | - Laurent Vinay
- Team P3M, Institut de Neurosciences de la Timone, UMR7289, Aix Marseille Université and Centre National de la Recherche Scientifique (CNRS) , Marseille, France
| |
Collapse
|
23
|
Marshall AG, Lee-Kubli C, Azmi S, Zhang M, Ferdousi M, Mixcoatl-Zecuatl T, Petropoulos IN, Ponirakis G, Fineman MS, Fadavi H, Frizzi K, Tavakoli M, Jeziorska M, Jolivalt CG, Boulton AJM, Efron N, Calcutt NA, Malik RA. Spinal Disinhibition in Experimental and Clinical Painful Diabetic Neuropathy. Diabetes 2017; 66:1380-1390. [PMID: 28202580 PMCID: PMC5399611 DOI: 10.2337/db16-1181] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/08/2017] [Indexed: 12/18/2022]
Abstract
Impaired rate-dependent depression (RDD) of the Hoffman reflex is associated with reduced dorsal spinal cord potassium chloride cotransporter expression and impaired spinal γ-aminobutyric acid type A receptor function, indicative of spinal inhibitory dysfunction. We have investigated the pathogenesis of impaired RDD in diabetic rodents exhibiting features of painful neuropathy and the translational potential of this marker of spinal inhibitory dysfunction in human painful diabetic neuropathy. Impaired RDD and allodynia were present in type 1 and type 2 diabetic rats but not in rats with type 1 diabetes receiving insulin supplementation that did not restore normoglycemia. Impaired RDD in diabetic rats was rapidly normalized by spinal delivery of duloxetine acting via 5-hydroxytryptamine type 2A receptors and temporally coincident with the alleviation of allodynia. Deficits in RDD and corneal nerve density were demonstrated in patients with painful diabetic neuropathy compared with healthy control subjects and patients with painless diabetic neuropathy. Spinal inhibitory dysfunction and peripheral small fiber pathology may contribute to the clinical phenotype in painful diabetic neuropathy. Deficits in RDD may help identify patients with spinally mediated painful diabetic neuropathy who may respond optimally to therapies such as duloxetine.
Collapse
Affiliation(s)
- Andrew G Marshall
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Department of Clinical Neurophysiology, Manchester Royal Infirmary, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester Academic Health Science Centre, Manchester, U.K
| | - Corinne Lee-Kubli
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Shazli Azmi
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Michael Zhang
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, U.K
| | - Maryam Ferdousi
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | | | - Ioannis N Petropoulos
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Georgios Ponirakis
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Mark S Fineman
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Hassan Fadavi
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Katie Frizzi
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Mitra Tavakoli
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
- Faculty of Medicine, University of Exeter Medical School, Exeter, U.K
| | - Maria Jeziorska
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Corinne G Jolivalt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Andrew J M Boulton
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K
| | - Nathan Efron
- School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
| | - Nigel A Calcutt
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | - Rayaz A Malik
- Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, Institute of Human Development, University of Manchester, and National Institute for Health Research/Wellcome Trust Clinical Research Facility, Manchester, U.K.
- Department of Medicine, Weill Cornell Medicine-Qatar, Doha, Qatar
| |
Collapse
|
24
|
Dideriksen J, Leerskov K, Czyzewska M, Rasmussen R. Relation Between the Frequency of Short-Pulse Electrical Stimulation of Afferent Nerve Fibers and Evoked Muscle Force. IEEE Trans Biomed Eng 2017; 64:2737-2745. [PMID: 28237919 DOI: 10.1109/tbme.2017.2671853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Objective: Functional electrical stimulation (FES) is conventionally performed by the stimulation of motor axons causing the muscle fibers innervated by these axons to contract. An alternative strategy that may evoke contractions with more natural motor unit behavior is to stimulate afferent fibers (primarily type Ia) to excite the motor neurons at the spinal level. The aim of the study was to investigate the range of forces that can be evoked in this way and the degree to which the torque can be controlled. Methods: We stimulated the tibial nerve of ten healthy participants at amplitudes at which the highest H-reflex with minimal M-wave was present. The evoked plantar flexion torque was recorded following short stimulation pulses (0.4 ms) with frequencies ranging from 20 to 200 Hz. Results: Across all subjects, the median highest evocable torque was 38.3% (quartiles: 16.9-51.0) of the maximum voluntary contraction torque (MVC). The average torque variability (standard deviation) was 1.7 +/- 0.7% MVC. For most subjects, the relation between stimulation frequency and evoked torque was well characterized by sigmoidal curves (median root mean square error: 6.4% MVC). The plateau of this sigmoid curve (indicating the range of frequencies over which torque amplitude could be modulated) was reached at 56.0 (quartiles: 29.4-81.9) Hz. Conclusion: Using the proposed method for FES, substantial evoked torques that could be controlled by stimulation frequency were achieved. Significance: Stimulation of afferent fibers could be a useful and fatigue-resistant strategy for several applications of FES.Objective: Functional electrical stimulation (FES) is conventionally performed by the stimulation of motor axons causing the muscle fibers innervated by these axons to contract. An alternative strategy that may evoke contractions with more natural motor unit behavior is to stimulate afferent fibers (primarily type Ia) to excite the motor neurons at the spinal level. The aim of the study was to investigate the range of forces that can be evoked in this way and the degree to which the torque can be controlled. Methods: We stimulated the tibial nerve of ten healthy participants at amplitudes at which the highest H-reflex with minimal M-wave was present. The evoked plantar flexion torque was recorded following short stimulation pulses (0.4 ms) with frequencies ranging from 20 to 200 Hz. Results: Across all subjects, the median highest evocable torque was 38.3% (quartiles: 16.9-51.0) of the maximum voluntary contraction torque (MVC). The average torque variability (standard deviation) was 1.7 +/- 0.7% MVC. For most subjects, the relation between stimulation frequency and evoked torque was well characterized by sigmoidal curves (median root mean square error: 6.4% MVC). The plateau of this sigmoid curve (indicating the range of frequencies over which torque amplitude could be modulated) was reached at 56.0 (quartiles: 29.4-81.9) Hz. Conclusion: Using the proposed method for FES, substantial evoked torques that could be controlled by stimulation frequency were achieved. Significance: Stimulation of afferent fibers could be a useful and fatigue-resistant strategy for several applications of FES.
Collapse
Affiliation(s)
- Jakob Dideriksen
- Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Kasper Leerskov
- Sensory-Motor Interaction, Department of Health Science and TechnologyAalborg University
| | - Magdalena Czyzewska
- Sensory-Motor Interaction, Department of Health Science and TechnologyAalborg University
| | - Rune Rasmussen
- Sensory-Motor Interaction, Department of Health Science and TechnologyAalborg University
| |
Collapse
|
25
|
Caron G, Marqueste T, Decherchi P. Restoration of post-activation depression of the H-reflex by treadmill exercise in aged rats. Neurobiol Aging 2016; 42:61-8. [DOI: 10.1016/j.neurobiolaging.2016.02.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 02/17/2016] [Accepted: 02/20/2016] [Indexed: 01/28/2023]
|
26
|
Hedegaard A, Lehnhoff J, Moldovan M, Grøndahl L, Petersen NC, Meehan CF. Postactivation depression of the Ia EPSP in motoneurons is reduced in both the G127X SOD1 model of amyotrophic lateral sclerosis and in aged mice. J Neurophysiol 2015; 114:1196-210. [PMID: 26084911 DOI: 10.1152/jn.00745.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 06/17/2015] [Indexed: 12/14/2022] Open
Abstract
Postactivation depression (PActD) of Ia afferent excitatory postsynaptic potentials (EPSPs) in spinal motoneurons results in a long-lasting depression of the stretch reflex. This phenomenon (PActD) is of clinical interest as it has been shown to be reduced in a number of spastic disorders. Using in vivo intracellular recordings of Ia EPSPs in adult mice, we demonstrate that PActD in adult (100-220 days old) C57BL/6J mice is both qualitatively and quantitatively similar to that which has been observed in larger animals with respect to both the magnitude (with ∼20% depression of EPSPs at 0.5 ms after a train of stimuli) and the time course (returning to almost normal amplitudes by 5 ms after the train). This validates the use of mouse models to study PActD. Changes in such excitatory inputs to spinal motoneurons may have important implications for hyperreflexia and/or glutamate-induced excitotoxicity in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). With the use of the G127X SOD1 mutant mouse, an ALS model with a prolonged asymptomatic phase and fulminant symptom onset, we observed that PActD is significantly reduced at both presymptomatic (16% depression) and symptomatic (17.3% depression) time points compared with aged-matched controls (22.4% depression). The PActD reduction was not markedly altered by symptom onset. Comparing these PActD changes at the EPSP with the known effect of the depression on the monosynaptic reflex, we conclude that this is likely to have a much larger effect on the reflex itself (a 20-40% difference). Nevertheless, it should also be accounted that in aged (580 day old) C57BL/6J mice there was also a reduction in PActD although, aging is not usually associated with spasticity.
Collapse
Affiliation(s)
- A Hedegaard
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - J Lehnhoff
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - M Moldovan
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - L Grøndahl
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - N C Petersen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and Department of Nutrition, Exercise and Sports, University of Copenhagen, Panum Institute, Copenhagen, Denmark
| | - C F Meehan
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| |
Collapse
|
27
|
Hofstoetter US, Danner SM, Freundl B, Binder H, Mayr W, Rattay F, Minassian K. Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord. J Neurophysiol 2015; 114:400-10. [PMID: 25904708 DOI: 10.1152/jn.00136.2015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/22/2015] [Indexed: 01/29/2023] Open
Abstract
In individuals with motor-complete spinal cord injury, epidural stimulation of the lumbosacral spinal cord at 2 Hz evokes unmodulated reflexes in the lower limbs, while stimulation at 22-60 Hz can generate rhythmic burstlike activity. Here we elaborated on an output pattern emerging at transitional stimulation frequencies with consecutively elicited reflexes alternating between large and small. We analyzed responses concomitantly elicited in thigh and leg muscle groups bilaterally by epidural stimulation in eight motor-complete spinal cord-injured individuals. Periodic amplitude modulation of at least 20 successive responses occurred in 31.4% of all available data sets with stimulation frequency set at 5-26 Hz, with highest prevalence at 16 Hz. It could be evoked in a single muscle group only but was more strongly expressed and consistent when occurring in pairs of antagonists or in the same muscle group bilaterally. Latencies and waveforms of the modulated reflexes corresponded to those of the unmodulated, monosynaptic responses to 2-Hz stimulation. We suggest that the cyclical changes of reflex excitability resulted from the interaction of facilitatory and inhibitory mechanisms emerging after specific delays and with distinct durations, including postactivation depression, recurrent inhibition and facilitation, as well as reafferent feedback activation. The emergence of large responses within the patterns at a rate of 5.5/s or 8/s may further suggest the entrainment of spinal mechanisms as involved in clonus. The study demonstrates that the human lumbosacral spinal cord can organize a simple form of rhythmicity through the repetitive activation of spinal reflex circuits.
Collapse
Affiliation(s)
- Ursula S Hofstoetter
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria;
| | - Simon M Danner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria; Institute of Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria; and
| | - Brigitta Freundl
- Neurological Center, Maria Theresien Schloessel, Otto Wagner Hospital, Vienna, Austria
| | - Heinrich Binder
- Neurological Center, Maria Theresien Schloessel, Otto Wagner Hospital, Vienna, Austria
| | - Winfried Mayr
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Frank Rattay
- Institute of Analysis and Scientific Computing, Vienna University of Technology, Vienna, Austria; and
| | - Karen Minassian
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| |
Collapse
|
28
|
Andrews JC, Stein RB, Roy FD. Post-activation depression in the human soleus muscle using peripheral nerve and transcutaneous spinal stimulation. Neurosci Lett 2015; 589:144-9. [PMID: 25600855 DOI: 10.1016/j.neulet.2015.01.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 01/07/2015] [Accepted: 01/15/2015] [Indexed: 11/24/2022]
Abstract
Transcutaneous stimulation of the human lumbar spine can be used to elicit root-evoked potentials (REPs). These sensory-motor responses display notable similarities to the monosynaptic H-reflex. The purpose of this study was to compare post-activation depression of the soleus REP to that of the H-reflex, when conditioned by either an H-reflex or an REP. Paired pulses were delivered 25-200ms apart and the recovery was characterized using three levels of stimulation. In all conditions, post-activation depression was reduced during contraction as compared to rest (P<0.001). REP doublets, delivered using an inter-pulse interval of 150ms, recovered to 68±8% of control during plantarflexion and 20±6% of control at rest. During contraction, recovery of a second REP was 65% of the corresponding recovery for a second H-reflex. The recovery of an H-reflex was equivalent, when conditioned by either an H-reflex or an REP, even though the spinal stimulus activated and/or engaged more afferent and efferent fibers. Our results suggest that the additional elements activated by the spinal stimulus did not affect the recovery of the H-reflex. However, the transcutaneous spinal stimulus produced more inhibition when it was assessed using two low-intensity REPs (P<0.05) suggesting that the pathway mediating the spinally-evoked response was more susceptible to being inhibited.
Collapse
Affiliation(s)
- Jennifer C Andrews
- Department of Physiology, University of Alberta, Edmonton, Canada; Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Richard B Stein
- Department of Physiology, University of Alberta, Edmonton, Canada; Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - François D Roy
- Department of Surgery, University of Alberta, Edmonton, Canada; Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada.
| |
Collapse
|
29
|
Calancie B, Donohue ML, Harris CB, Canute GW, Singla A, Wilcoxen KG, Moquin RR. Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria. J Neurosurg Spine 2014; 20:675-91. [DOI: 10.3171/2014.2.spine13648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Reports of the accuracy of existing neuromonitoring methods for detecting or preventing medial malpositioning of thoracic pedicle screws have varied widely in their claimed effectiveness. The object of this study was to develop, test, and validate a novel neuromonitoring method for preventing medial malpositioning of pedicle screws in the thoracic spine during surgery.
Methods
This is a prospective, blinded and randomized study using a novel combination of input (4-pulse stimulus trains delivered within the pedicle track) and output (evoked electromyography from leg muscles) to detect pedicle track trajectories that—once implanted with a screw—would cause that screw to breach the pedicle's medial wall and encroach upon the spinal canal. For comparison, the authors also used screw stimulation as an input and evoked electromyogram from intercostal and abdominal muscles as output measures. Intraoperative electrophysiological findings were compared with postoperative CT scans by multiple reviewers blinded to patient identity or intraoperative findings.
Results
Data were collected from 71 patients, in whom 802 screws were implanted between the T-1 and L-1 vertebral levels. A total of 32 screws ended up with screw threads encroaching on the spinal canal by at least 2 mm. Pulse-train stimulation within the pedicle track using a ball-tipped probe and electromyography from lower limb muscles correctly predicted all 32 (100%) of these medially malpositioned screws. The combination of pedicle track stimulation and electromyogram response from leg muscles proved to be far more effective in predicting these medially malpositioned screws than was direct screw stimulation and any of the target muscles (intercostal, abdominal, or lower limb muscles) we monitored. Based on receiver operating characteristic analysis, the combination of 10-mA (lower alarm) and 15-mA stimulation intensities proved most effective for detection of pedicle tracks that ultimately gave rise to medially malpositioned screws. Additional results pertaining to the impact of feedback of these test results on surgical decision making are provided in the companion report.
Conclusions
This novel neuromonitoring approach accurately predicts medially malpositioned thoracic screws. The approach could be readily implemented within any surgical program that is already using contemporary neuromonitoring methods that include transcranial stimulation for monitoring motor evoked potentials.
Collapse
|
30
|
Trompetto C, Marinelli L, Mori L, Canneva S, Colombano F, Traverso E, Currà A, Abbruzzese G. The effect of age on post-activation depression of the upper limb H-reflex. Eur J Appl Physiol 2013; 114:359-64. [PMID: 24292018 DOI: 10.1007/s00421-013-2778-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 11/16/2013] [Indexed: 11/24/2022]
Abstract
PURPOSE Post-activation depression (PaD) refers to the inhibition of the H-reflex induced by a preceding conditioning stimulus able to activate the afferents mediating the H-reflex itself. PaD can be investigated assessing the frequency-related depression of the H-reflex. This parameter, which is highly correlated to the severity of spasticity, has been used in the longitudinal assessment of spastic patients, in particular to assess the effect of drugs and rehabilitation over the years. However, in such longitudinal assessment, changes observed might be age related and not only disease related. The aim of this study was to investigate the possible age effects on PaD. METHODS The frequency-related depression of the flexor carpi radialis (FCR) H-reflex was examined in two groups of young (20 subjects; 28 ± 3 years) and aged (18 subjects; 69 ± 6 years) healthy subjects. PaD was evaluated by comparing the H-reflex amplitudes obtained with a stimulation frequency of 0.1 Hz with those obtained using higher frequencies (0.33-0.5-1-2 Hz). RESULTS The results showed that frequency-related depression of the FCR H-reflex is similar in young and elderly subjects at all frequencies, with the exception of 2 Hz. CONCLUSION Our study shows that ageing does not affect the frequency-related depression of the FCR H-reflex at the frequencies of 1 Hz or lower, supporting the reliability of this method to assess PaD in the clinical practice, particularly for the longitudinal assessment of spasticity. A decrease of GABA-ergic presynaptic inhibition seems to be the more likely explanation for the age-related changes that we observed at the frequency of 2 Hz.
Collapse
Affiliation(s)
- Carlo Trompetto
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Institute of Neurology, University of Genova, Largo Daneo 3, 16132, Genoa, Italy
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Lee-Kubli CAG, Calcutt NA. Altered rate-dependent depression of the spinal H-reflex as an indicator of spinal disinhibition in models of neuropathic pain. Pain 2013; 155:250-260. [PMID: 24103402 DOI: 10.1016/j.pain.2013.10.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 10/01/2013] [Accepted: 10/01/2013] [Indexed: 12/17/2022]
Abstract
The unpredictable efficacy of current therapies for neuropathic pain may reflect diverse etiological mechanisms operating between, and within, diseases. As descriptions of pain rarely establish specific mechanisms, a tool that can identify underlying causes of neuropathic pain would be useful in developing patient-specific treatments. Rate-dependent depression (RDD), a measure of the change in amplitude of the Hoffman reflex over consecutive stimulations, is attenuated in diabetic rats that also exhibit impaired spinal γ-aminobutyric acid (GABA)A receptor function, reduced spinal potassium chloride co-transporter (KCC2) expression, and indices of painful neuropathy. To investigate whether loss of RDD is a reliable indicator of the contribution of spinal GABAergic dysfunction to neuropathic pain, we assessed RDD, tactile allodynia, and formalin-evoked hyperalgesia in 3 models: rats treated acutely with brain-derived neurotrophic factor (BDNF), diabetic rats treated with the BDNF-sequestering molecule tyrosine receptor kinase B/Fc (TrkB/Fc), and rats with paclitaxel-induced neuropathy. Delivery of BDNF to the spinal cord of normal rats produced RDD deficits and features of painful neuropathy associated with disrupted GABAA receptor-mediated inhibitory function and reduced dorsal spinal KCC2 expression. Treating diabetic rats with TrkB/Fc restored RDD and alleviated indices of painful neuropathy. In paclitaxel-treated rats, RDD was not impaired and behavioral indices of neuropathic pain were not associated with spinal GABAergic dysfunction or reduced dorsal spinal KCC2 expression. Our data reveal BDNF as part of the mechanism underlying spinal cord disinhibition caused by altered GABAA receptor function in diabetic rats and suggest that RDD deficits may be a useful indicator of neuropathic pain states associated with spinal disinhibition, thereby revealing specific therapeutic targets.
Collapse
Affiliation(s)
- Corinne A G Lee-Kubli
- Department of Pathology, University of California San Diego, La Jolla, CA 92093, USA Graduate School of Biomedical Sciences, Sanford-Burnham Institute for Medical Research, La Jolla, CA 92037, USA
| | | |
Collapse
|
32
|
Effects of Continuous Passive Motion on Reversing the Adapted Spinal Circuit in Humans With Chronic Spinal Cord Injury. Arch Phys Med Rehabil 2013; 94:822-8. [DOI: 10.1016/j.apmr.2012.11.035] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 11/08/2012] [Accepted: 11/25/2012] [Indexed: 11/18/2022]
|
33
|
Clair-Auger JM, Lagerquist O, Collins DF. Depression and recovery of reflex amplitude during electrical stimulation after spinal cord injury. Clin Neurophysiol 2012; 124:723-31. [PMID: 23117117 DOI: 10.1016/j.clinph.2012.09.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 09/07/2012] [Accepted: 09/25/2012] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aim of this study was to quantify, for the first time, H-reflexes evoked during prolonged trains of wide-pulse neuromuscular electrical stimulation (WP-NMES) in individuals with chronic spinal cord injury (SCI). We hypothesised that after the first H-reflex, reflex amplitudes would be depressed (due to post-activation depression), but would recover and this recovery would be enhanced after a "burst" of 100 Hz WP-NMES. METHODS Soleus M-waves and H-reflexes evoked during WP-NMES (1 ms pulse width) of the tibial nerve were quantified in nine individuals with SCI. WP-NMES was delivered in two patterns: "constant-frequency" (15 or 20 Hz for 12 s) and "burst-like" (15-100-15 Hz or 20-100-20 Hz; 4 s each phase) at an intensity that evoked an M-wave between 10% and 15% of the maximal M-wave (M(max)). RESULTS During constant frequency stimulation, after the initial depression from the first to the second H-reflex (1st: 57% M(max); 2nd: 25% M(max)), H-reflexes did not recover significantly and were 37% M(max) at the end of the stimulus train. During the burst-like pattern, after the initial depression (1st: 62% M(max); 2nd: 30%), reflexes recovered completely by the end of the stimulation (to 55% M(max)) as they were not significantly different from the first H-reflex. M-waves were initially depressed (1st: 12% M(max); 2nd: 7% M(max)) then did not change throughout the stimulation and were not significantly different between stimulation patterns. An analysis of covariance indicated that the depression in M-wave amplitude did not account for the depression in H-reflex amplitude. CONCLUSIONS Relatively large H-reflexes were recorded during both patterns of NMES. The brief burst of 100 Hz stimulation restored H-reflexes to their initial amplitudes, effectively reversing the effects of post-activation depression. SIGNIFICANCE For individuals with chronic SCI, generating contractions through central pathways may help reduce muscle atrophy and produce contractions that are more fatigue-resistant for rehabilitation, exercise programs, or to perform activities of daily living.
Collapse
Affiliation(s)
- J M Clair-Auger
- Centre for Neuroscience, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | | | | |
Collapse
|
34
|
Bose PK, Hou J, Parmer R, Reier PJ, Thompson FJ. Altered patterns of reflex excitability, balance, and locomotion following spinal cord injury and locomotor training. Front Physiol 2012; 3:258. [PMID: 22934014 PMCID: PMC3429034 DOI: 10.3389/fphys.2012.00258] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 06/20/2012] [Indexed: 11/13/2022] Open
Abstract
Spasticity is an important problem that complicates daily living in many individuals with spinal cord injury (SCI). While previous studies in human and animals revealed significant improvements in locomotor ability with treadmill locomotor training, it is not known to what extent locomotor training influences spasticity. In addition, it would be of considerable practical interest to know how the more ergonomically feasible cycle training compares with treadmill training as therapy to manage SCI-induced spasticity and to improve locomotor function. Thus the main objective of our present studies was to evaluate the influence of different types of locomotor training on measures of limb spasticity, gait, and reflex components that contribute to locomotion. For these studies, 30 animals received midthoracic SCI using the standard Multicenter Animal Spinal cord Injury Studies (MASCIS) protocol (10 g 2.5 cm weight drop). They were divided randomly into three equal groups: control (contused untrained), contused treadmill trained, and contused cycle trained. Treadmill and cycle training were started on post-injury day 8. Velocity-dependent ankle torque was tested across a wide range of velocities (612-49°/s) to permit quantitation of tonic (low velocity) and dynamic (high velocity) contributions to lower limb spasticity. By post-injury weeks 4 and 6, the untrained group revealed significant velocity-dependent ankle extensor spasticity, compared to pre-surgical control values. At these post-injury time points, spasticity was not observed in either of the two training groups. Instead, a significantly milder form of velocity-dependent spasticity was detected at postcontusion weeks 8-12 in both treadmill and bicycle training groups at the four fastest ankle rotation velocities (350-612°/s). Locomotor training using treadmill or bicycle also produced significant increase in the rate of recovery of limb placement measures (limb axis, base of support, and open field locomotor ability) and reflex rate-depression, a quantitative assessment of neurophysiological processes that regulate segmental reflex excitability, compared with those of untrained injured controls. Light microscopic qualitative studies of spared tissue revealed better preservation of myelin, axons, and collagen morphology in both locomotor trained animals. Both locomotor trained groups revealed decreased lesion volume (rostro-caudal extension) and more spared tissue at the lesion site. These improvements were accompanied by marked upregulation of BDNF, GABA/GABA(b), and monoamines (e.g., norepinephrine and serotonin) which might account for these improved functions. These data are the first to indicate that the therapeutic efficacy of ergonomically practical cycle training is equal to that of the more labor-intensive treadmill training in reducing spasticity and improving locomotion following SCI in an animal model.
Collapse
Affiliation(s)
- Prodip K Bose
- Brain Rehabilitation Research Center, North Florida/South Georgia VA Medical Center Gainesville, FL, USA
| | | | | | | | | |
Collapse
|
35
|
Yates C, Garrison K. Translational Research on Spinal Cord Injury. Transl Neurosci 2011. [DOI: 10.1002/9781118260470.ch7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
|
36
|
Clair JM, Anderson-Reid JM, Graham CM, Collins DF. Postactivation depression and recovery of reflex transmission during repetitive electrical stimulation of the human tibial nerve. J Neurophysiol 2011; 106:184-92. [PMID: 21511709 DOI: 10.1152/jn.00932.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
H-reflexes are progressively depressed, relative to the first response, at stimulation frequencies above 0.1 Hz (postactivation depression; PAD). Presently, we investigated whether H-reflexes "recover" from this depression throughout 10-s trains of stimulation delivered at physiologically relevant frequencies (5-20 Hz) during functionally relevant tasks (sitting and standing) and contraction amplitudes [relaxed to 20% maximum voluntary contraction (MVC)]. When participants held a 10% MVC, reflex amplitudes did not change during 5-Hz stimulation. During stimulation at 10 Hz, reflexes were initially depressed by 43% but recovered completely by the end of the stimulation period. During 20-Hz stimulation, reflexes were depressed to 10% and recovered to 36% of the first response, respectively. This "postactivation depression and recovery" (PAD&R) of reflex amplitude was not different between sitting and standing. In contrast, PAD&R were strongly influenced by contraction amplitude. Reflexes were depressed to 10% of the first response during the relaxed condition (10-Hz stimulation) and showed no depression during a 20% MVC contraction. A partial recovery of reflex amplitude occurred when participants were relaxed and during contractions of 1-5% MVC. Surprisingly, reflexes could recover completely by the third pulse within a stimulation train when participants held a contraction between 5 and 10% MVC during stimulation at 10 Hz, a finding that challenges classical ideas regarding PAD mechanisms. Our results support the idea that there is an ongoing interplay between depression and facilitation when motoneurons receive trains of afferent input. This interplay depends strongly on the frequency of the afferent input and the magnitude of the background contraction but is relatively insensitive to changes in task.
Collapse
Affiliation(s)
- Joanna M Clair
- Centre for Neuroscience, Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | | | | | | |
Collapse
|
37
|
Yates C, Garrison K, Reese NB, Charlesworth A, Garcia-Rill E. Chapter 11--novel mechanism for hyperreflexia and spasticity. PROGRESS IN BRAIN RESEARCH 2011; 188:167-80. [PMID: 21333809 DOI: 10.1016/b978-0-444-53825-3.00016-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We established that hyperreflexia is delayed after spinal transection in the adult rat and that passive exercise could normalize low frequency-dependent depression of the H-reflex. We were also able to show that such passive exercise will normalize hyperreflexia in patients with spinal cord injury (SCI). Recent results demonstrate that spinal transection results in changes in the neuronal gap junction protein connexin 36 below the level of the lesion. Moreover, a drug known to increase electrical coupling was found to normalize hyperreflexia in the absence of passive exercise, suggesting that changes in electrical coupling may be involved in hyperreflexia. We also present results showing that a measure of spasticity, the stretch reflex, is rendered abnormal by transection and normalized by the same drug. These data suggest that electrical coupling may be dysregulated in SCI, leading to some of the symptoms observed. A novel therapy for hyperreflexia and spasticity may require modulation of electrical coupling.
Collapse
Affiliation(s)
- C Yates
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | | | | | | | | |
Collapse
|
38
|
Abstract
AbstractSpasticity is evident in both humans and animals following spinal cord injury (SCI) and can contribute to significant functional limitation and disruption in quality of life of patients with this disorder. This mini-review describes a number of preclinical and clinical studies that promise to improve outcomes for, especially in terms of spasticity and hyper-reflexia, patients with SCI. A gold standard for the quantification of spasticity has proved elusive, but the combination of H-reflex frequency dependent depression and a novel stretch reflex (SR) windup protocol have the potential to provide new insights. As the pathophysiology of hyper-reflexia and spasticity continue to be investigated, the documented onset in the animal model of SCI provides critical time points for further study into these complex mechanisms. The positive effects of a passive exercise protocol and several potential pharmacological interventions are reviewed as well as a novel potential mechanism of action. Further work is needed to determine additional mechanisms that are involved in SCI, and how to optimize multiple therapies to overcome some of the deficits induced by SCI.
Collapse
|
39
|
Clarac F, Massion J, Stuart DG. Reflections on Jacques Paillard (1920–2006) — A pioneer in the field of motor cognition. ACTA ACUST UNITED AC 2009; 61:256-80. [DOI: 10.1016/j.brainresrev.2009.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 06/30/2009] [Accepted: 07/20/2009] [Indexed: 10/20/2022]
|
40
|
McNulty PA, Jankelowitz SK, Wiendels TM, Burke D. Postactivation Depression of the Soleus H Reflex Measured Using Threshold Tracking. J Neurophysiol 2008; 100:3275-84. [PMID: 18922951 DOI: 10.1152/jn.90435.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interpretation of changes in the soleus H reflex is problematic in the face of reflex gain changes, a nonlinear input/output relationship for the motoneuron pool, and a nonhomogeneous response of different motoneurons to afferent inputs. By altering the stimulus intensity to maintain a constant reflex output, threshold tracking allows a relatively constant population of α-motoneurons to be studied. This approach was used to examine postactivation (“homosynaptic”) depression of the H reflex (HD) in 23 neurologically healthy subjects. The H reflex was elicited by tibial nerve stimulation at 0.05, 0.1, 0.3, 1, and 2 Hz at rest and during voluntary plantar flexion at 2.5, 5, and 10% of maximum. A computerized threshold tracking procedure was used to set the current needed to generate a target H reflex 10% of Mmax. The current needed to produce the target reflex increased with stimulus rate but not significantly beyond 1 Hz. In three subjects, the current needed to produce H reflexes of 5, 10, 15, and 20% Mmax at 0.3, 1, and 2 Hz increased with rate and with the size of the test H reflex. HD was significantly reduced during voluntary contractions. Using threshold tracking, HD was maximal at lower frequencies than previously emphasized, probably because HD is greater the larger the test H reflex. This would reinforce the greater sensitivity of small motoneurons to reflex inputs.
Collapse
|
41
|
Yates CC, Charlesworth A, Reese NB, Skinner RD, Garcia-Rill E. The effects of passive exercise therapy initiated prior to or after the development of hyperreflexia following spinal transection. Exp Neurol 2008; 213:405-9. [PMID: 18671970 PMCID: PMC2689156 DOI: 10.1016/j.expneurol.2008.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 06/28/2008] [Accepted: 07/02/2008] [Indexed: 11/22/2022]
Abstract
Hyperreflexia develops after spinal cord injury (SCI) in the human and in the spinal cord transected animal, and can be measured by the loss of low frequency-dependent depression of the H-reflex. Previous studies demonstrated normalization of low frequency-dependent depression of the H-reflex using passive exercise when initiated prior to the development of hyperreflexia. We examined the effects of passive exercise prior to compared to after the development of hyperreflexia in the transected rat. Adult female rats underwent complete transection (Tx) at T10. Frequency-dependence of the H-reflex was tested following passive exercise for 30 days, initiated prior to hyperreflexia in one group compared to initiation after hyperreflexia became established, and compared to intact and untreated Tx groups. An additional Tx group completed 60 days of exercise initiated after hyperreflexia was established. Lumbar enlargement tissue was harvested for western blot to compare Connexin-36 protein levels in control vs Tx animals vs Tx animals that were passively exercised. No differences in whole tissue were evident, although regional differences may still be present in Connexin-36 levels. Statistically significant decreases in low frequency-dependent depression of the H-reflex were observed following 30 days of exercise initiated prior to the onset of hyperreflexia, and also after 60 days of exercise when initiated after hyperreflexia had been established, compared with Tx only animals. We concluded that modulation of spinal circuitry by passive exercise took place when initiated before and after the onset of hyperreflexia, but different durations of exercise were required.
Collapse
Affiliation(s)
- Charlotte C Yates
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72035, USA.
| | | | | | | | | |
Collapse
|
42
|
Frigon A, Rossignol S. Functional plasticity following spinal cord lesions. PROGRESS IN BRAIN RESEARCH 2006; 157:231-260. [PMID: 17167915 DOI: 10.1016/s0079-6123(06)57016-5] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Spinal cord injury results in marked modification and reorganization of several reflex pathways caudal to the injury. The sudden loss or disruption of descending input engenders substantial changes at the level of primary afferents, interneurons, and motoneurons thus dramatically influencing sensorimotor interactions in the spinal cord. As a general rule reflexes are initially depressed following spinal cord injury due to severe reductions in motoneuron excitability but recover and in some instances become exaggerated. It is thought that modified inhibitory connections and/or altered transmission in some of these reflex pathways after spinal injury as well as the recovery and enhancement of membrane properties in motoneurons underlie several symptoms such as spasticity and may explain some characteristics of spinal locomotion observed in spinally transected animals. Indeed, after partial or complete spinal lesions at the last thoracic vertebra cats recover locomotion when the hindlimbs are placed on a treadmill. Although some deficits in spinal locomotion are related to lesion of specific descending motor pathways, other characteristics can also be explained by changes in the excitability of reflex pathways mentioned above. Consequently it may be the case that to reestablish a stable walking pattern that modified afferent inflow to the spinal cord incurred after injury must be normalized to enable a more normal re-expression of locomotor rhythm generating networks. Indeed, recent evidence demonstrates that step training, which has extensively been shown to facilitate and ameliorate locomotor recovery in spinal animals, directly influences transmission in simple reflex pathways after complete spinal lesions.
Collapse
Affiliation(s)
- Alain Frigon
- Center and Group for Neurological Sciences, CIHR Group in Neurological Sciences, CIHR Regenerative Medicine and Nanomedicine Team, Faculty of Medicine, Université de Montréal, Montreal, QC, Canada
| | | |
Collapse
|
43
|
Reese NB, Skinner RD, Mitchell D, Yates C, Barnes CN, Kiser TS, Garcia-Rill E. Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats. Spinal Cord 2005; 44:28-34. [PMID: 16044168 DOI: 10.1038/sj.sc.3101810] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Hyper-reflexia, measured as a decrease of low frequency-dependent depression of the H-reflex, is known to occur in both humans and animals after spinal cord injury (SCI). Previous studies have shown that passive exercise for 3 months could be used to restore low frequency-dependent depression of the H-reflex after SCI. OBJECTIVE To determine the effects of various periods of time on the ability of passive exercise to restore low frequency-dependent depression of the H-reflex. SETTING Spinal Cord Injury Mobilization Program of the Center for Translational Neuroscience, the research arm of the Jackson T Stephens Spine and Neuroscience Institute, Little Rock, AR, USA. METHODS Adult rats underwent complete spinal cord transection at the T10 level. The hindlimbs were passively exercised in different groups of rats for 1 h/day, 5 days/week for 15, 30, 45, 60, or 90 days, and low frequency-dependent depression of the H-reflex was tested. RESULTS Statistically significant low frequency-dependent depression of the H-reflex was evident by 30 days of exercise, although numerical reductions were seen even at 15 days. There was a linear decrease in low frequency-dependent depression of the H-reflex with duration of passive exercise. CONCLUSIONS Passive exercise can restore frequency-dependent depression of spinal reflexes in a time-dependent manner if used following complete spinal transection.
Collapse
Affiliation(s)
- N B Reese
- Department of Physical Therapy, University of Central Arkansas, Conway, AR 72205, USA
| | | | | | | | | | | | | |
Collapse
|
44
|
Bose P, Parmer R, Reier PJ, Thompson FJ. Morphological changes of the soleus motoneuron pool in chronic midthoracic contused rats. Exp Neurol 2005; 191:13-23. [PMID: 15589508 DOI: 10.1016/j.expneurol.2004.08.028] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Revised: 08/10/2004] [Accepted: 08/24/2004] [Indexed: 11/23/2022]
Abstract
This study investigated the morphological features of the soleus motoneuron pool in rats with chronic (4 months), midthoracic (T8) contusions of moderate severity. Motoneurons were retrogradely labeled using unconjugated cholera toxin B (CTB) subunit solution injected directly into the soleus muscle of 10 contused and 6 age- and sex-matched, normal controls. Morphometric studies compared somal area, perimeter, diameter, dendritic length, and size distribution of labeled cells in normal and postcontusion animals. In normal animals, motoneurons with a mean of 110.4 +/- 5.2 were labeled on the toxin-injected side of the cord (left). By comparison, labeled cells with a mean of 93.0 +/- 8.4 (a 16% decrease, P = 0.006) were observed in the chronic spinal-injured animals. A significantly smaller frequency of very small (area, approximately 100 microm2) and medium (area, 545-914 microm2) neurons, and a significantly higher frequency of larger (area, >914 microm2) neurons was observed in the labeled soleus motoneuron pools of injured animals compared with the normal controls. Dendritic bundles in the contused animals were composed of thicker dendrites, were arranged in more closely aggregated bundles, and were organized in a longitudinal axis (rostrocaudal axis). Changes in soleus motoneuron dendritic morphology also included significant decrease of total number of dendrites, increased staining, hypertrophy of primary dendrites, and significant decreased primary, secondary, and tertiary branching. The changes in size distribution and dendritic morphology in the postcontusion animals possibly resulted from cell loss and transformation of medium cells to larger cells and/or injury-associated failure of medium cells to transport the immunolabel.
Collapse
Affiliation(s)
- Prodip Bose
- Department of Neuroscience, McKnight Brain Institute at the University of Florida College of Medicine, Gainesville, FL 32611, USA.
| | | | | | | |
Collapse
|
45
|
Schindler-Ivens SM, Shields RK. Soleus H-reflex recruitment is not altered in persons with chronic spinal cord injury 11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors(s) or upon any organization with which the author(s) is/are associated. Arch Phys Med Rehabil 2004; 85:840-7. [PMID: 15129411 PMCID: PMC3298881 DOI: 10.1016/j.apmr.2003.08.087] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To determine whether spasticity in persons with spinal cord injury (SCI) is associated with elevated monosynaptic reflex excitability. DESIGN One-way experimental. SETTING Research laboratory. PARTICIPANTS Convenience sample of 9 subjects (8 men, 1 woman) with chronic and complete SCI and 20 persons (14 men, 6 women) with no neurologic impairment. Subjects with SCI exhibited lower-extremity spasticity as indicated by velocity-dependent increased resistance to passive muscle stretch, abnormally brisk deep tendon reflexes, involuntary lower-extremity flexion and/or extension spasms, and clonus. INTERVENTION Soleus H-reflex recruitment curves were elicited in all subjects. MAIN OUTCOME MEASURES Soleus H-reflex threshold (HTH), gain (HGN), and amplitude (HPP). RESULTS There was no difference between subjects with and without SCI in HTH, HGN, or HPP. CONCLUSIONS Spasticity in people with chronic and complete SCI was not associated with increased excitability of the connections between Ia afferent projections and motoneurons. Factors extrinsic to these connections may have a role in spasticity caused by SCI.
Collapse
Affiliation(s)
- Sheila M Schindler-Ivens
- Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, IA, USA.
| | | |
Collapse
|
46
|
Mezzarane RA, Kohn AF. Bilateral soleus H-reflexes in humans elicited by simultaneous trains of stimuli: symmetry, variability, and covariance. J Neurophysiol 2002; 87:2074-83. [PMID: 11929925 DOI: 10.1152/jn.00129.2001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Experiments using electrical and mechanical activation of spinal reflexes have contributed important results toward the understanding of neuronal and synaptic dynamics involved in spinal neural circuits as well as their response to different inputs. In this work, data obtained from the simultaneous stimulation of both legs are analyzed to provide information on the degree of symmetry of the respective spinal reflex circuits and on the characteristics of reflex variability. H-reflexes recorded from relaxed muscles show a frequency-dependent amplitude depression when elicited by a train of stimuli. This effect has been attributed to homosynaptic depression. Soleus H-reflexes were recorded in response to trains of simultaneous stimuli applied to both legs in right-handed subjects that were sitting in a relaxed state. The first objective was to verify the existence of asymmetries in H-reflex parameters obtained from the two legs. We measured the mean, variance, and coefficient of variation of the depressed H-reflex amplitudes and the time constant of decay toward the depressed plateau. The second objective was the analysis of the time correlation of subsequent H-reflex amplitudes in a long train of responses recorded from a given leg. The statistical dependence of H-reflex amplitudes in the long trains recorded from both legs was also investigated. Data obtained from preliminary experiments showed that there was no effect of a given stimulus on the contralateral leg applied simultaneously or 1 s before, therefore validating the simultaneous stimulation paradigm. Paired t-tests indicated that several parameters measured bilaterally from soleus H-reflex trains of right-handed subjects were not statistically different in the overall, although individually there were statistically significant asymmetries, toward either the right or left leg. Sequences of H-reflex amplitudes, as measured by the auto-covariance, were either white or had a memory ranging from 2 up to 50 s. This indicates that the random fluctuations in presynaptic inhibition and/or postsynaptic inputs to motoneurons may have either fast or slow time courses. The average auto-covariance sequences of the right and left legs, computed from all subjects, were practically superposable. The cross-covariance between the bilateral H-reflex amplitudes showed a statistically significant peak at zero lag in some experiments, suggesting a correlation between the synaptic inputs to the Ia-motoneuron systems of the soleus muscles of both legs.
Collapse
Affiliation(s)
- Rinaldo A Mezzarane
- Neuroscience Program and Biomedical Engineering Laboratory, Escola Politécnica, University of São Paulo, CEP 05424-970 São Paulo, SP, Brazil
| | | |
Collapse
|
47
|
Thompson FJ, Reier PJ, Uthman B, Mott S, Fessler RG, Behrman A, Trimble M, Anderson DK, Wirth ED. Neurophysiological assessment of the feasibility and safety of neural tissue transplantation in patients with syringomyelia. J Neurotrauma 2001; 18:931-45. [PMID: 11565604 DOI: 10.1089/089771501750451848] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The feasibility and safety of a procedure involving fetal spinal cord tissue transplantation in patients with syringomyelia was assessed using a neurophysiological protocol designed to quantitate peripheral nerve function, spinal cord reflex excitability, and spinal cord conduction pathways essential for somatosensory evoked potentials. We report here data obtained before and for 18 months following the transplantation procedure performed on the first two patients in this study. The neurophysiological assessment protocols included measures of cortical and spinal cord evoked potentials, H-reflex excitability, and peripheral nerve conduction. Prior to the procedure, both patients had significant deficits on some of the neurophysiological measures, for example, lower extremity cortical evoked potentials. However, robust measures of intact pathways, such as upper extremity cortical evoked potentials, were also observed preoperatively in both patients. Thus, it was anticipated that conduction in these intact pathways could be at risk either from complications from the transplantation procedure and/or from continued expansion of the syrinx. Following the transplantation procedure, no negative changes were observed in any of the neurophysiological measures in either patient. In addition, patient 1 showed a decrease in the rate potentiation of tibial H-reflexes on the right side and an increase in the response probability of left tibial H-reflexes. The results of this postoperative longitudinal assessment provide a first-level demonstration of the safety of the intraspinal neural tissue transplantation procedure. However, the consideration of safety is currently limited to the grafting procedure itself, since the long-term fates of the donor tissue in these two patients remain to be shown more definitively.
Collapse
Affiliation(s)
- F J Thompson
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Abstract
A variety of central nervous system injuries, diseases, and developmental deficits can lead to motor disorders that present complex mixtures of symptoms. Those that have a fundamental similarity characterized by the appearance of exaggerated velocity-dependent resistance to the lengthening of skeletal muscles are called spasticity. Reports based on clinical observations of motor disorders have and continue to provide the essential database of information regarding the range and distribution of unifying and discordant features of spasticity. Laboratory investigations employing animal models of motor disorders following experimental lesions of the central nervous system have reproduced some of the neurophysiologic changes that accompany injury of the central nervous system in humans. Those experimental lesions produced by spinal cord contusion/compression reproduce many of the histopathologic features displayed in traumatic injury of the human spinal cord as well. Studies using this model have revealed not only changes in reflex threshold and amplitude but also alterations in fundamental rate-modulation processes that regulate reflex excitability during repetitive stimulation. This report characterizes insights obtained from a laboratory investigation in search of fundamental mechanisms that contribute to the development of spasticity and provides a vantage point for understanding therapeutic strategies for treatment of spasticity.
Collapse
Affiliation(s)
- F J Thompson
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville 32610, USA.
| | | | | | | | | |
Collapse
|
49
|
Schindler-Ivens S, Shields RK. Low frequency depression of H-reflexes in humans with acute and chronic spinal-cord injury. Exp Brain Res 2000; 133:233-41. [PMID: 10968224 PMCID: PMC4034370 DOI: 10.1007/s002210000377] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We measured low-frequency depression of soleus H-reflexes in individuals with acute (n=5) and chronic (n=7) spinal-cord injury and in able-bodied controls (n=7). In one acute subject, we monitored longitudinal changes in low-frequency depression of H-reflexes over 44 weeks and examined the relationship between H-reflex depression and soleus-muscle fatigue properties. Soleus H-reflexes were elicited at 0.1, 0.2, 1, 5, and 10 Hz. The mean peak-to-peak amplitude of ten reflexes at each frequency was calculated, and values obtained at each frequency were normalized to 0.1 Hz. H-reflex amplitude decreased with increasing stimulation frequency in all three groups, but H-reflex suppression was significantly larger in the able-bodied and acute groups than in the chronic group. The acute subject who was monitored longitudinally displayed reduced low-frequency depression with increasing time post injury. At 44 weeks post injury, the acute subject's H-reflex depression was similar to that of chronic subjects, and his soleus fatigue index (assessed with a modified Burke fatigue protocol) dropped substantially, consistent with transformation to faster muscle. There was a significant inverse correlation over the 44 weeks between the fatigue index and the mean normalized H-reflex amplitude at 1, 5, and 10 Hz. We conclude that: (1) the chronically paralyzed soleus muscle displays impaired low-frequency depression of H-reflexes, (2) attenuation of rate-sensitive depression in humans with spinal-cord injury occurs gradually, and (3) changes in H-reflex excitability are generally correlated with adaptation of the neuromuscular system. Possible mechanisms underlying changes in low-frequency depression and their association with neuromuscular adaptation are discussed.
Collapse
Affiliation(s)
- S Schindler-Ivens
- Physical Therapy Graduate Program, The University of Iowa, Iowa City 52242-1008, USA
| | | |
Collapse
|
50
|
Trimble MH. Postural modulation of the segmental reflex: effect of body tilt and postural sway. Int J Neurosci 1998; 95:85-100. [PMID: 9845019 DOI: 10.3109/00207459809000652] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This purpose of this study was to clarify the relationship between segmental reflex excitability and posture and to investigate potential mechanisms responsible for modulation of the H-reflex (HR) in unsupported standing. Soleus (S) and lateral gastrocnemius (LG) HRs were recorded from subjects (N=12S, N=11LG) while their static posture was altered from supine to vertical (5 positions). This was compared to an unsupported standing position in which the subjects naturally underwent a small degree of postural sway, a dynamic posture condition. Although individual profiles suggested varied relationships between the S and LGHR and the angle of body tilt, the group data did not reveal significant differences. There was, however, a significant (p < .01) decrease in the S (43% 49%) and LG (34%-46%) HR when subjects stood without support compared to all static postures. This decrease occurred even though the tonic or background activity of the S and LG was present only when subjects were free standing. To determine whether weight-bearing was responsible for the HR depression, 3 additional conditions were compared (N=3), supported standing without weight-bearing (90 degrees NWB), supported standing with weight-bearing (90 degrees WB), and free standing. Again, S and LGHRs were depressed only when subjects were free standing. Presynaptic inhibition presumably accounts for the depression of the HR in unsupported standing. Data from 8 of the subjects were collected under the same 6 conditions using a shorter interstimulus interval (1 Hz stimulus instead of 0.1 Hz) which produced low frequency depression (LFD) of the S and LG HR. LFD reduced the amplitude of the S HR an average of 43% (p < .05) when subjects were in a supported static position but only 21% when subjects were free standing. Although tonic activity of the S was present only when subjects were free standing, in 2 (of 8) individuals the EMG in free standing was not measurably different from static conditions. In these individuals, free standing still depressed the SHR by 35%; however, the shorter stimulus interval now produced the same degree of LFD when subjects were free standing (35%) as when they were standing with support (37%). The data suggest that 2 presynaptic mechanisms, although independent, interact to control spindle afferent feedback when subjects are free standing. Postural sway appears to be necessary to reduce the gain of the HR when subjects are standing, whereas, LFD is influenced by the degree of muscle activation.
Collapse
Affiliation(s)
- M H Trimble
- Department of Physical Therapy, University of Florida, Gainesville 32610-0154, USA.
| |
Collapse
|