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Hamza M, Carron R, Dibué M, Moiraghi A, Barrit S, Filipescu C, Landré E, Gavaret M, Domenech P, Pallud J, Zanello M. Right-sided vagus nerve stimulation for drug-resistant epilepsy: A systematic review of the literature and perspectives. Seizure 2024; 117:298-304. [PMID: 38615369 DOI: 10.1016/j.seizure.2024.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 02/11/2024] [Accepted: 02/18/2024] [Indexed: 04/16/2024] Open
Abstract
BACKGROUND Right-sided vagus nerve stimulation (RS-VNS) is indicated when the procedure was deemed not technically feasible or too risky on the indicated left side. OBJECTIVE The present study aims to systematically review the literature on RS-VNS, assessing its effectiveness and safety. METHODS A systematic review following PRISMA guidelines was conducted: Pubmed/MEDLINE, The Cochrane Library, Scopus, Embase and Web of science databases were searched from inception to August 13th,2023. Gray literature was searched in two libraries. Eligible studies included all studies reporting, at least, one single case of RS-VNS in patients for the treatment of drug-resistant epilepsy. RESULTS Out of 2333 initial results, 415 studies were screened by abstract. Only four were included in the final analysis comprising seven patients with RS-VNS for a drug-resistant epilepsy. One patient experienced nocturnal asymptomatic bradycardia whereas the other six patients did not display any cardiac symptom. RS-VNS was discontinued in one case due to exercise-induced airway disease exacerbation. Decrease of epileptic seizure frequency after RS-VNS ranged from 25 % to 100 % in six cases. In the remaining case, VNS effectiveness was unclear. In one case, RS-VNS was more efficient than left-sided VNS (69 % vs 50 %, respectively) whereas in another case, RS-VNS was less efficient (50 % vs 95 %, respectively). CONCLUSION Literature on the present topic is limited. In six out of seven patients, RS-VNS for drug-resistant epilepsy displayed reasonable effectiveness with a low complication rate. Further research, including prospective studies, is necessary to assess safety and effectiveness of RS-VNS for drug-resistant epilepsy patients.
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Affiliation(s)
- Meissa Hamza
- Department of Neurosurgery, GHU Paris - Sainte-Anne Hospital, Paris, France; Paris Descartes University, Sorbonne Paris Cité, Paris, France
| | - Romain Carron
- Aix Marseille Université, INSERM, INS, Institut de Neurosciences des Systèmes, Marseille, France; Department of Functional and Stereotactic Neurosurgery, Timone University Hospital, Marseille, France
| | - Maxine Dibué
- Department of Neurosurgery, Friedrich-Schiller University, Jena, Germany; Medical Affairs Neuromodulation International, LivaNova PLC, London United Kingdom
| | - Alessandro Moiraghi
- Department of Neurosurgery, GHU Paris - Sainte-Anne Hospital, Paris, France; Paris Descartes University, Sorbonne Paris Cité, Paris, France; Université Paris Cité, INSERM UMR1266, IPNP, Paris, France
| | - Sami Barrit
- Department of Neurosurgery, Erasmus Hospital, Free University of Brussels, Belgium
| | - Cristina Filipescu
- Neurophysiology Department, GHU Paris Psychiatrie et Neurosciences, Sainte-Anne Hospital, Paris, France
| | - Elisabeth Landré
- Neurophysiology Department, GHU Paris Psychiatrie et Neurosciences, Sainte-Anne Hospital, Paris, France
| | - Martine Gavaret
- Paris Descartes University, Sorbonne Paris Cité, Paris, France; Université Paris Cité, INSERM UMR1266, IPNP, Paris, France; Neurophysiology Department, GHU Paris Psychiatrie et Neurosciences, Sainte-Anne Hospital, Paris, France
| | - Philippe Domenech
- Neuromodulation Institute, GHU Paris, Psychiatrie et neurosciences, Hôpital Saint-Anne, Université Paris Cité, Paris, France; Cognitive Neuroimaging Unit, INSERM, CEA, CNRS, Université Paris-Saclay, NeuroSpin Center, France
| | - Johan Pallud
- Department of Neurosurgery, GHU Paris - Sainte-Anne Hospital, Paris, France; Paris Descartes University, Sorbonne Paris Cité, Paris, France; Université Paris Cité, INSERM UMR1266, IPNP, Paris, France
| | - Marc Zanello
- Department of Neurosurgery, GHU Paris - Sainte-Anne Hospital, Paris, France; Paris Descartes University, Sorbonne Paris Cité, Paris, France; Université Paris Cité, INSERM UMR1266, IPNP, Paris, France.
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Uehara S, Yuasa A, Ushizawa K, Kodera S, Kamimura Y, Hirata A, Otaka Y. Characteristics of current perception produced by intermediate-frequency contact currents in healthy adults. Front Neurosci 2023; 17:1145505. [PMID: 37179562 PMCID: PMC10166820 DOI: 10.3389/fnins.2023.1145505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 04/03/2023] [Indexed: 05/15/2023] Open
Abstract
Introduction Contact electrical currents in humans stimulate peripheral nerves at frequencies of <100 kHz, producing sensations such as tingling. At frequencies above 100 kHz, heating becomes dominant, resulting in a sensation of warmth. When the current amplitude exceeds the threshold, the sensation results in discomfort or pain. In international guidelines and standards for human protection from electromagnetic fields, the limit for the contact current amplitude has been prescribed. Although the types of sensations produced by contact current at low frequencies, i.e., approximately 50-60 Hz, and the corresponding perception thresholds have been investigated, there is a lack of knowledge about those in the intermediate-frequency band-particularly from 100 kHz to 10 MHz. Methods In this study, we investigated the current-perception threshold and types of sensations for 88 healthy adults (range: 20-79 years old) with a fingertip exposed to contact currents at 100 kHz, 300 kHz, 1 MHz, 3 MHz, and 10 MHz. Results The current perception thresholds at frequencies ranging from 300 kHz to 10 MHz were 20-30% higher than those at 100 kHz (p < 0.001). In addition, a statistical analysis revealed that the perception thresholds were correlated with the age or finger circumference: older participants and those with larger finger circumferences exhibited higher thresholds. At frequencies of ≥300 kHz, the contact current mainly produced a warmth sensation, which differed from the tingling/pricking sensation produced by the current at 100 kHz. Discussion These results indicate that there exists a transition of the produced sensations and their perception threshold between 100 kHz and 300 kHz. The findings of this study are useful for revising the international guidelines and standards for contact currents at intermediate frequencies. Clinical trial registration https://center6.umin.ac.jp/cgi-open-bin/icdr_e/ctr_view.cgi?recptno=R000045660, identifier UMIN 000045213.
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Affiliation(s)
- Shintaro Uehara
- Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Akiko Yuasa
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Kazuki Ushizawa
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
| | - Sachiko Kodera
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Yoshitsugu Kamimura
- Department of Fundamental Engineering, School of Engineering, Utsunomiya University, Utsunomiya, Japan
| | - Akimasa Hirata
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
- Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya, Japan
| | - Yohei Otaka
- Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Japan
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Poulsen AH, van den Berg B, Arguissain FG, Tigerholm J, Buitenweg JR, Andersen OK, Mørch CD. Novel surface electrode design for preferential activation of cutaneous nociceptors. J Neural Eng 2022; 19. [PMID: 34996054 DOI: 10.1088/1741-2552/ac4950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 01/07/2022] [Indexed: 11/11/2022]
Abstract
Objective Small area electrodes enable preferential activation of nociceptive fibers. It is debated, however, whether co-activation of large fibers still occurs for the existing electrode designs. Moreover, existing electrodes are limited to low stimulation intensities, for which behavioral and physiological responses may be considered less reliable. A recent optimization study showed that there is a potential for improving electrode performance and increase the range of possible stimulation intensities. Based on those results, the present study introduces and tests a novel planar concentric array electrode design for small fiber activation in healthy volunteers. Approach Volunteers received electrical stimulation with the planar concentric array electrode and a regular patch electrode. Perception thresholds were estimated at the beginning and the end of the experiment. Evoked cortical potentials were recorded in blocks of 30 stimuli. For the patch, stimulation intensity was set to two times perception threshold (PT), while three intensities, 2, 5, and 10 times PT, were applied with the planar concentric array electrode. Sensation quality, numerical-rating scores, and reaction times were obtained for each PT estimation and during each block of evoked potential recordings. Main results Stimulation with the patch electrode was characterized as dull, while stimulation with the planar concentric array electrode was characterized as sharp, with increased sharpness for increasing stimulus intensity. Likewise, NRS scores were higher for the planar concentric array electrode compared to the patch and increased with increasing stimulation intensity. Reaction times and ERP latencies were longer for the planar concentric array electrode compared to the patch. Significance The presented novel planar concentric array electrode is a small, non-invasive, and single-use electrode that has the potential to investigate small fiber neuropathy and pain mechanisms, as it is small fiber preferential for a wide range of stimulation intensities.
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Affiliation(s)
- Aida Hejlskov Poulsen
- Department of Health science and technology, Aalborg Universitet Det Sundhedsvidenskabelige Fakultet, Fredrik bajers vej, 7 A1, 208, Aalborg, Nordjylland, 9220, DENMARK
| | - Boudewijn van den Berg
- University of Twente Technical Medical Centre, PO box 217, 7500 AE Enschede, The Netherlands, Enschede, 7500, NETHERLANDS
| | - Federico G Arguissain
- Department of Health Science and Technology, Aalborg Universitet Det Sundhedsvidenskabelige Fakultet, Fredrik Bajers Vej 7A, Aalborg, 9220, DENMARK
| | - Jenny Tigerholm
- Health Science and Technology, Aalborg University, Fredrik Bajers vej 7A, Aalborg, 9220, DENMARK
| | - Jan R Buitenweg
- EWI - TST, University of Twente, PO Box 217, 7500 AE Enchende, The Netherlands, Enschende, 7500, NETHERLANDS
| | - Ole Kaeseler Andersen
- Department of Health Science and Technology, Aalborg Universitet Det Sundhedsvidenskabelige Fakultet, Fredrik Bajers Vej 7, 9220 Aalborg, Aalborg, 9220, DENMARK
| | - Carsten Dahl Mørch
- Department of Health Science and Technology, Aalborg Universitet Det Sundhedsvidenskabelige Fakultet, Fredrik Bajers Vej 7 A, Aalborg, 9220, DENMARK
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Liu K, Yin L, Ma Z, Yu B, Ma Y, Huang L. Effect of Different Kinesio Taping Interventions on the Local Thresholds of Current Perception and Pressure Pain in Healthy Adults. Front Physiol 2020; 11:596159. [PMID: 33281628 PMCID: PMC7689279 DOI: 10.3389/fphys.2020.596159] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/21/2020] [Indexed: 12/04/2022] Open
Abstract
Objective Previous studies made controversial claims about the alleged effects of Kinesio taping (KT) on pain relief. To date, the mechanism by which KT relieves pain remains unclear. Moreover, pain evaluation lacks objective and quantitative parameters. This study compared the acute effects of different KT interventions on the local thresholds of pressure pain and current perception in healthy adults to determine the potential mechanisms by which KT relieves pain. Methods Thirty healthy female subjects randomly received four KT interventions, namely, no taping (NT), placebo taping (PT), Y strips of KT (KY), and fan strips of KT (KF), on the waist. Current perception threshold (CPT), pressure pain threshold (PPT), soft tissue hardness, and the visual analog scale (VAS) scores of the subjects’ perceived pain were immediately measured after taping. Repeated-measures ANOVA was performed to determine significant differences in these parameters among the four interventions. Results Significant differences in CPT values among the interventions were observed at the frequency of 5 Hz (F = 3.499, p = 0.019, ηp2 = 0.111). Post hoc analysis revealed that CPT was significantly higher for KF than for NT (p = 0.008, 95% CI = 1.390–11.990). Significant differences in PPT values (F = 4.352, p = 0.012, ηp2 = 0.130) and soft tissue hardness (F = 2.957, p = 0.049, ηp2 = 0.093) were observed among the different taping conditions. Post hoc analysis revealed that PPT was significantly higher for KF than for PT (p = 0.011, 95% CI = 0.071–0.749), and soft tissue hardness was significantly higher for KF than for NT (p = 0.010, 95% CI = 0.461–4.586) and KY (p = 0.040, 95% CI = 0.059–3.800). No significant differences in self-perceived pain among the interventions were observed. Conclusion The healthy adult females had higher PPT values, lower soft tissue hardness, and higher CPT values at 5 Hz under KF intervention applied on the waist than those under the other taping interventions. Moreover, the different taping conditions had no significant differences in terms of VAS of perceived pain. These results provide guidance for the application of KT on pain management.
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Affiliation(s)
- Kun Liu
- Department of Rehabilitation Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Lulu Yin
- Department of Critical Care Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Zheng Ma
- Department of Rehabilitation Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Bo Yu
- Department of Rehabilitation, School of International Medical Technology, Sanda University, Shanghai, China
| | - Yanhong Ma
- Department of Rehabilitation Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Lihua Huang
- Department of Rehabilitation Medicine, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
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Chang W, Xu W, Zhang R, An Y. References Values for the Current Perception Threshold in the Pharynx Based on a Study of a Healthy Population. Ann Otol Rhinol Laryngol 2020; 130:699-705. [PMID: 33111543 DOI: 10.1177/0003489420967707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES The application of the current perception threshold (CPT) in the diagnosis of pharyngeal sensory abnormalities has rarely been studied, and there is a lack of reference values for this application. This study established a normal reference range for CPT in the pharynx based on a study of a healthy population. METHODS The CPT values of the palatoglossal arch, posterior 1/3 of the lingual body and hard palate were measured in 60 healthy individuals at 2000, 250, and 5 Hz. The influencing factors were analyzed, and reference values for the CPT were established. RESULTS There was no correlation between the CPT value and gender. Age was only correlated at 250 Hz level in the hard palate. The CPT values of the palatoglossal arch were 324.95 ± 82.422 at 2000 Hz, 66.90 ± 38.622 at 250 Hz, and 13 ± 14.93 (7.83-22.75) at 5 Hz. The CPT values of the posterior 1/3 of the lingual body were 359.17 ± 76.299 at 2000 Hz, 86.92 ± 35.151 at 250 Hz, and 19 ± 15.73 (13.03-28.75) at 5 Hz. The CPT values of the hard palate were 157.5 ± 61.75 (124-185.75) at 2000 Hz, 57.63 ± 28.785 at 250 Hz, and 22 ± 25.73 (11.03-36.75) at 5 Hz. CONCLUSIONS The CPT values of the pharynx in healthy people were not related to gender. The CPT values of the hard palate for 250 Hz stimulation were related to age, and there were no relationships between the CPT values and age for the other frequencies and loci. We established a normal reference range of CPT values in the pharynx from measurements obtained from healthy populations.
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Affiliation(s)
- Wei Chang
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, P.R. China.,Department of Otolaryngology Head and Neck Surgery, Heping Hospital Affiliated to Changzhi Medical College, Changzhi, P.R. China
| | - Wen Xu
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, P.R. China
| | - Ran Zhang
- Department of Rehabilitation Medicine, Beijing Tongren Hospital, Capital Medical University, Beijing, P.R. China
| | - Yunsong An
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, P.R. China
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Chang W, Xu W, Hu R, An Y. Current Perception Threshold Testing in Pharyngeal Paresthesia Patients with Depression or Anxiety. Neuropsychiatr Dis Treat 2020; 16:1023-1029. [PMID: 32368064 PMCID: PMC7182447 DOI: 10.2147/ndt.s248236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/08/2020] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Satisfactory quantitative diagnostic approaches to pharyngeal paresthesia patients with depression or anxiety remain to be explored. This study investigated the plausibility of current perception threshold (CPT) testing in diagnosing pharyngeal paresthesia in patients with depression or anxiety. PATIENTS AND METHODS A total of 41 patients with pharyngeal paresthesia with depression or anxiety were recruited as the study group. Additionally, 60 healthy volunteers constituted the control group. The CPT values associated with 5-, 250-, and 2000-Hz electrical stimulation frequencies were measured at the palatal lingual arch and posterior third of the lingual body (two sensory nerve distribution sites in the pharynx). The normal range of CPT values of the above three frequencies was analyzed. The differences in the CPT values for sensory nerves were compared. RESULTS There were no significant differences in age and sex between the study and control groups. The CPT values of the pharynx at the two tested sites were not significantly correlated with age and gender. The CPT value of the study group was significantly lower than that of the control group in the palatal lingual arch and posterior third of the lingual body at an electrical stimulation of 5 Hz (p<0.05). No significant differences in the CPT values at other frequencies were found between the two groups. CONCLUSION CPT testing is effective in determining pharyngeal paresthesia in patients with depression and anxiety. Paresthesia of the pharyngeal sensory nerve region is caused by damaged C fibers.
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Affiliation(s)
- Wei Chang
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, People's Republic of China
| | - Wen Xu
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, People's Republic of China
| | - Rong Hu
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, People's Republic of China
| | - Yunsong An
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, People's Republic of China
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Yin H, Liu M, Zhu Y, Cui L. Reference Values and Influencing Factors Analysis for Current Perception Threshold Testing Based on Study of 166 Healthy Chinese. Front Neurosci 2018; 12:14. [PMID: 29434533 PMCID: PMC5790867 DOI: 10.3389/fnins.2018.00014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 01/10/2018] [Indexed: 11/30/2022] Open
Abstract
The current perception threshold (CPT) is a device which can evaluate different sensory fibers quantitatively through different frequencies of the electrical stimulus and has been applied in clinical practice. Previous studies have implied that CPT values may be affected by age, gender, and other factors, yet not conclusively. The objective of our study is to clarify the influencing factors of CPT values and establish a reference value range. Twenty healthy volunteers recruited publicly and 146 subjects who took CPT tests in the census of the national project cardiovascular and cerebrovascular diseases in rural areas of China from 2013 to 2015 were analyzed. Past medical history and demographic characteristics such as age, gender, and occupation were collected. Each subject was tested on the left index finger (or back of the left hand) and the right hallux. CPT values of 2000, 250, and 5 Hz on both sites were recorded for statistical analysis. Gender differences were shown at 2000 Hz CPT on the back of the hand and hallux (p < 0.01), and male subjects had a higher CPT. Age had a positive correlation with 250 Hz CPT on the index finger (p < 0.05, r = 1.5), 2000 Hz CPT on the back of the hand (p < 0.001, r = 1.2) and index finger (p < 0.05, r = 2.5). Manual workers had a higher 250 Hz CPT on the hallux than mental workers (p < 0.01). After investigating the impact of different factors on CPT testing, we established the reference value for subjects with different characteristics.
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Affiliation(s)
- Hexiang Yin
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Mingsheng Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Yicheng Zhu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Liying Cui
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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Moving Toward Conscious Pain Processing Detection in Chronic Disorders of Consciousness: Anterior Cingulate Cortex Neuromodulation. THE JOURNAL OF PAIN 2015. [DOI: 10.1016/j.jpain.2015.06.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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On the selective activation of unmyelinated C-fibers using sinusoidal electrical stimulation: an ERP study. Clin Neurophysiol 2011; 122:1042-7. [PMID: 21353630 DOI: 10.1016/j.clinph.2011.01.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 01/07/2011] [Accepted: 01/31/2011] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To verify the possibility of selective activation of C-fibers by a 5-Hz transcutaneous electrical stimulus. METHODS Because Aβ-, Aδ- and C-fibers have different conduction velocities, we verified the selective activation of A- and C-fibers on the basis of evoked potential latencies. We tested whether a 5-Hz sinusoidal electric stimulus could selectively activate C-fibers and consequently generate ultra-late N2/P2 components in the 750-1200 ms range. RESULTS We found that a 5-Hz sine wave stimulus, whether of high or low intensity, elicited N2/P2 complexes only in the late latencies (160-390 ms), suggesting that A-fibers were concomitantly activated along with C-fibers. CONCLUSIONS These findings are in agreement with those of previous simulation studies suggesting that activation of fibers of diameter less than 2.5 μm (i.e., C-fibers) at the 5-Hz frequency requires accompanying activity from Aβ- and Aδ-fibers. SIGNIFICANCE Transcutaneous electrical stimulation with sine wave currents of different frequencies does not seem to be a reliable method for the selective assessment of somatosensory pathways.
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