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Kofler M, Hallett M, Iannetti GD, Versace V, Ellrich J, Téllez MJ, Valls-Solé J. The blink reflex and its modulation - Part 1: Physiological mechanisms. Clin Neurophysiol 2024; 160:130-152. [PMID: 38102022 PMCID: PMC10978309 DOI: 10.1016/j.clinph.2023.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 11/11/2023] [Accepted: 11/22/2023] [Indexed: 12/17/2023]
Abstract
The blink reflex (BR) is a protective eye-closure reflex mediated by brainstem circuits. The BR is usually evoked by electrical supraorbital nerve stimulation but can be elicited by a variety of sensory modalities. It has a long history in clinical neurophysiology practice. Less is known, however, about the many ways to modulate the BR. Various neurophysiological techniques can be applied to examine different aspects of afferent and efferent BR modulation. In this line, classical conditioning, prepulse and paired-pulse stimulation, and BR elicitation by self-stimulation may serve to investigate various aspects of brainstem connectivity. The BR may be used as a tool to quantify top-down modulation based on implicit assessment of the value of blinking in a given situation, e.g., depending on changes in stimulus location and probability of occurrence. Understanding the role of non-nociceptive and nociceptive fibers in eliciting a BR is important to get insight into the underlying neural circuitry. Finally, the use of BRs and other brainstem reflexes under general anesthesia may help to advance our knowledge of the brainstem in areas not amenable in awake intact humans. This review summarizes talks held by the Brainstem Special Interest Group of the International Federation of Clinical Neurophysiology at the International Congress of Clinical Neurophysiology 2022 in Geneva, Switzerland, and provides a state-of-the-art overview of the physiology of BR modulation. Understanding the principles of BR modulation is fundamental for a valid and thoughtful clinical application (reviewed in part 2) (Gunduz et al., submitted).
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Affiliation(s)
- Markus Kofler
- Department of Neurology, Hochzirl Hospital, Zirl, Austria.
| | - Mark Hallett
- National Institute of Neurological Disorders and Stroke, NIH, USA.
| | - Gian Domenico Iannetti
- University College London, United Kingdom; Italian Institute of Technology (IIT), Rome, Italy.
| | - Viviana Versace
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Teaching Hospital of the Paracelsus Medical Private University (PMU), Vipiteno-Sterzing, Italy.
| | - Jens Ellrich
- Friedrich-Alexander-University Erlangen-Nuremberg, Germany.
| | | | - Josep Valls-Solé
- IDIBAPS (Institut d'Investigació August Pi i Sunyer), University of Barcelona, Spain.
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Hamedani AG, Gold DR. Eyelid Dysfunction in Neurodegenerative, Neurogenetic, and Neurometabolic Disease. Front Neurol 2017; 8:329. [PMID: 28769865 PMCID: PMC5513921 DOI: 10.3389/fneur.2017.00329] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/23/2017] [Indexed: 12/18/2022] Open
Abstract
Eye movement abnormalities are among the earliest clinical manifestations of inherited and acquired neurodegenerative diseases and play an integral role in their diagnosis. Eyelid movement is neuroanatomically linked to eye movement, and thus eyelid dysfunction can also be a distinguishing feature of neurodegenerative disease and complements eye movement abnormalities in helping us to understand their pathophysiology. In this review, we summarize the various eyelid abnormalities that can occur in neurodegenerative, neurogenetic, and neurometabolic diseases. We discuss eyelid disorders, such as ptosis, eyelid retraction, abnormal spontaneous and reflexive blinking, blepharospasm, and eyelid apraxia in the context of the neuroanatomic pathways that are affected. We also review the literature regarding the prevalence of eyelid abnormalities in different neurologic diseases as well as treatment strategies (Table 1).
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Affiliation(s)
- Ali G Hamedani
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, United States
| | - Daniel R Gold
- Department of Neurology, Johns Hopkins Hospital, Baltimore, MD, United States.,Department of Ophthalmology, Johns Hopkins Hospital, Baltimore, MD, United States.,Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, MD, United States.,Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins Hospital, Baltimore, MD, United States
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Leon-Sarmiento FE, Peckham E, Leon-Ariza DS, Bara-Jimenez W, Hallett M. Auditory and Lower Limb Tactile Prepulse Inhibition in Primary Restless Legs Syndrome: Clues to Its Pathophysiology. J Clin Neurophysiol 2016; 32:369-74. [PMID: 26241246 DOI: 10.1097/wnp.0000000000000196] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The resting sensory discomfort transiently relieved upon movement of the affected area in restless legs syndrome suggests that sensorimotor integration mechanisms, specifically gating, may be altered in the disease. The authors sought to determine the effects of prepulse auditory and tactile stimulation applied to lower limbs on the blink reflex of patients with restless legs syndrome and healthy subjects. Seventeen patients with restless legs syndrome and 17 age- and sex-matched healthy controls were investigated. Auditory stimuli and tactile lower limb stimulation were applied as prepulses. The R2 response of the blink reflex induced by electrical stimulation applied to the right supraorbital nerve was selected as the test stimulus. Time intervals between prepulses and response-eliciting stimuli were 40, 70, 90, 110, and 200 milliseconds. There were no differences in either the auditory or tactile prepulse conditions between patients and controls and no differences between these measures within subject groups. We concluded that the tactile lower limb and the auditory prepulse effects on the brainstem interneurons mediating the blink reflex share common neural pathways. Because forebrain interneurons mediate these prepulse effects, they are likely not involved in the disordered sensorimotor interaction of restless legs syndrome.
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Affiliation(s)
- Fidias E Leon-Sarmiento
- *Human Motor Control Section, NINDS, National Institutes of Health, Bethesda, Maryland, U.S.A.; †Smell and Taste Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, U.S.A.; ‡Mediciencias Research Group, Unicolciencias/Universidad Nacional, Bogota, Colombia; and §Faculty of Health, Universidad de Santander (UDES), Bucaramanga, Colombia
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Abstract
This review examines the current level of knowledge and techniques available for the study of laryngeal reflexes. Overall, the larynx is under constant control of several systems (including respiration, swallowing and cough) as well as sensory motor reflex responses involving glossopharyngeal, pharyngeal, laryngeal, and tracheobronchial sensory receptors. Techniques for the clinical assessment of these reflexes are emerging and need to be examined for sensitivity and specificity in identifying laryngeal sensory disorders. Quantitative assessment methods for the diagnosis of sensory reductions and sensory hypersensitivity may account for laryngeal disorders, such as chronic cough, paradoxical vocal fold disorder, and muscular tension dysphonia. The development of accurate assessment techniques could improve our understanding of the mechanisms involved in these disorders.
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Srivanitchapoom P, Hallett M. Camptocormia in Parkinson's disease: definition, epidemiology, pathogenesis and treatment modalities. J Neurol Neurosurg Psychiatry 2016; 87:75-85. [PMID: 25896683 PMCID: PMC5582594 DOI: 10.1136/jnnp-2014-310049] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/30/2015] [Indexed: 12/22/2022]
Abstract
Camptocormia is an axial postural deformity characterised by abnormal thoracolumbar spinal flexion. The symptom usually presents while standing, walking or exercising and is alleviated while sitting, lying in a recumbent position, standing against a wall or using walking support. There is no consensus on the degree of thoracolumbar flexion to define camptocormia. However, most authors usually use an arbitrary number of at least 45° flexion of the thoracolumbar spine when the individual is standing or walking. Aetiologies of camptocormia are heterogeneous, and Parkinson's disease (PD) is one of its many causes. The prevalence of camptocormia in PD ranges from 3% to 18%. Central and peripheral mechanisms might both contribute to its pathogenesis. Although there is no established consensus for treatment of camptocormia in PD, there are non-pharmacological, pharmacological and surgical approaches that can be used.
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Affiliation(s)
- Prachaya Srivanitchapoom
- Faculty of Medicine, Division of Neurology, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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Kiziltan ME, Gunduz A, Apaydın H, Ertan S, Kiziltan G. Auditory startle reflex and startle reflex to somatosensory inputs in generalized dystonia. Clin Neurophysiol 2015; 126:1740-5. [DOI: 10.1016/j.clinph.2014.11.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/13/2014] [Accepted: 11/03/2014] [Indexed: 11/25/2022]
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Konczak J, Aman JE, Chen YW, Li KY, Watson PJ. Impaired Limb Proprioception in Adults With Spasmodic Dysphonia. J Voice 2015; 29:777.e17-23. [PMID: 25737471 DOI: 10.1016/j.jvoice.2014.12.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 12/23/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Focal dystonia of the head and neck are associated with a loss of kinesthetic acuity at muscles distant from the dystonic sites. That is, while the motor deficits in focal dystonia are confined, the associated somatosensory deficits are generalized. This is the first systematic study to examine, if patients diagnosed with spasmodic dystonia (SD) show somatosensory impairments similar in scope to other forms of focal dystonia. METHODS Proprioceptive acuity (ability to discriminate between two stimuli) for forearm position and motion sense was assessed in 14 spasmodic dystonia subjects and 28 age-matched controls using a passive motion apparatus. Psychophysical thresholds, uncertainty area (UA), and a proprioceptive acuity index (AI) were computed based on the subjects' verbal responses. RESULTS The main findings are as follows: first, the SD group showed significantly elevated thresholds and UAs for forearm position sense compared with the control group. Second, 9 of 14 dystonia subjects (64%) exhibited an AI for position sense above the control group maximum. Three SD subjects had a motion sense AI above the control group maximum. CONCLUSIONS The results indicate that impaired limb proprioception is a common feature of SD. Like other forms of focal dystonia, spasmodic dystonia does affect the somatosensation of nondystonic muscle systems. That is, SD is associated with a generalized somatosensory deficit.
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Affiliation(s)
- Jürgen Konczak
- Human Sensorimotor Control Laboratory, University of Minnesota, Minneapolis, Minnesota.
| | - Joshua E Aman
- Human Sensorimotor Control Laboratory, University of Minnesota, Minneapolis, Minnesota
| | - Yu-Wen Chen
- Department of Speech-Language-Hearing Sciences, University of Minnesota, Minneapolis, Minnesota
| | - Kuan-yi Li
- Department of Occupational Therapy, Graduate Institute of Behavioral Sciences, Healthy Aging Center, Chang Gung University, Taoyuan, Taiwan
| | - Peter J Watson
- Department of Speech-Language-Hearing Sciences, University of Minnesota, Minneapolis, Minnesota
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Abnormal control of orbicularis oculi reflex excitability in multiple sclerosis. PLoS One 2014; 9:e103897. [PMID: 25083902 PMCID: PMC4118978 DOI: 10.1371/journal.pone.0103897] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 07/07/2014] [Indexed: 11/20/2022] Open
Abstract
Brain lesions in patients with multiple sclerosis may lead to abnormal excitability of brainstem reflex circuits because of impairment of descending control pathways. We hypothesized that such abnormality should show in the analysis of blink reflex responses in the form of asymmetries in response size. The study was done in 20 patients with relapsing-remitting multiple sclerosis and 12 matched healthy subjects. We identified first patients with latency abnormalities (AbLat). Then, we analyzed response size by calculating the R2c/R2 ratio to stimulation of either side and the mean area of the R2 responses obtained in the same side. Patients with significantly larger response size with respect to healthy subjects in at least one side were considered to have abnormal response excitability (AbEx). We also examined the blink reflex excitability recovery (BRER) and prepulse inhibition (BRIP) of either side in search for additional indices of asymmetry in response excitability. Neurophysiological data were correlated with MRI-determined brain lesion-load and volume. Eight patients were identified as AbLat (median Expanded Disability Status Scale–EDSS = 2.75) and 7 of them had ponto-medullary lesions. Nine patients were identified as AbEx (EDSS = 1.5) and only 2 of them, who also were AbLat, had ponto-medullary lesions. In AbEx patients, the abnormalities in response size were confined to one side, with a similar tendency in most variables (significantly asymmetric R1 amplitude, BRER index and BRIP percentage). AbEx patients had asymmetric distribution of hemispheral lesions, in contrast with the symmetric pattern observed in AbLat. The brainstem lesion load was significantly lower in AbEx than in AbLat patients (p = 0.04). Asymmetric abnormalities in blink reflex response excitability in patients with multiple sclerosis are associated with lesser disability and lower tissue loss than abnormalities in response latency. Testing response excitability could provide a reliable neurophysiological index of dysfunction in early stages of multiple sclerosis.
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The role of the trigeminal sensory nuclear complex in the pathophysiology of craniocervical dystonia. J Neurosci 2014; 33:18358-67. [PMID: 24259561 DOI: 10.1523/jneurosci.3544-13.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Isolated focal dystonia is a neurological disorder that manifests as repetitive involuntary spasms and/or aberrant postures of the affected body part. Craniocervical dystonia involves muscles of the eye, jaw, larynx, or neck. The pathophysiology is unclear, and effective therapies are limited. One mechanism for increased muscle activity in craniocervical dystonia is loss of inhibition involving the trigeminal sensory nuclear complex (TSNC). The TSNC is tightly integrated into functionally connected regions subserving sensorimotor control of the neck and face. It mediates both excitatory and inhibitory reflexes of the jaw, face, and neck. These reflexes are often aberrant in craniocervical dystonia, leading to our hypothesis that the TSNC may play a central role in these particular focal dystonias. In this review, we present a hypothetical extended brain network model that includes the TSNC in describing the pathophysiology of craniocervical dystonia. Our model suggests the TSNC may become hyperexcitable due to loss of tonic inhibition by functionally connected motor nuclei such as the motor cortex, basal ganglia, and cerebellum. Disordered sensory input from trigeminal nerve afferents, such as aberrant feedback from dystonic muscles, may continue to potentiate brainstem circuits subserving craniocervical muscle control. We suggest that potentiation of the TSNC may also contribute to disordered sensorimotor control of face and neck muscles via ascending and cortical descending projections. Better understanding of the role of the TSNC within the extended neural network contributing to the pathophysiology of craniocervical dystonia may facilitate the development of new therapies such as noninvasive brain stimulation.
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Nisticò R, Salsone M, Vescio B, Morelli M, Trotta M, Barbagallo G, Arabia G, Quattrone A. Blink reflex recovery cycle distinguishes essential tremor with resting tremor from de novo Parkinson's disease: an exploratory study. Parkinsonism Relat Disord 2013; 20:153-6. [PMID: 24572624 DOI: 10.1016/j.parkreldis.2013.10.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 09/30/2013] [Accepted: 10/08/2013] [Indexed: 10/26/2022]
Abstract
An increased R2 recovery component of the blink reflex (R2-BRrc) has been observed in Parkinson's disease (PD), cranio-cervical dystonia, dystonic tremor and essential tremor with associated resting tremor (rET), while the BRrc was reported normal in patients with essential tremor (ET). Distinguishing rET from tremor dominant PD (tPD) may be challenging especially in the first stages of the diseases, in the absence of DAT-SPECT investigation. We evaluated the possible usefulness of BRrc for differentiating subjects with de novo tPD from those with rET. We investigated R2-BRrc at interstimulus intervals (ISI) of 100, 150, 200, 300, 400, 500 and 750 ms in 11 participants with tPD, 10 with rET and 20 healthy controls. All participants underwent DAT-SPECT and cardiac MIBG scintigraphy. R2 recovery was significantly enhanced in tPD compared to controls at all investigated ISIs (p < 0.001), while in subjects with rET patients BRrc was significantly increased compared to controls at ISI 150, 200, 300, 400, 500 and 750 ms (p < 0.001). At ISI 100 R2-BRrc distinguished patients participants with de novo tPD from those with rET with a sensitivity, specificity and accuracy of 100%. Our findings demonstrate the usefulness of BRrc for differentiating de novo tPD from rET.
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Affiliation(s)
- R Nisticò
- Neuroimaging Research Unit, Catanzaro, Italy
| | - M Salsone
- The Institute of Neurology, Department of Medical Sciences, University Magna Graecia, Campus Universitario Germaneto, Viale Europa, Catanzaro 88100, Italy
| | - B Vescio
- Neuroimaging Research Unit, Catanzaro, Italy
| | - M Morelli
- The Institute of Neurology, Department of Medical Sciences, University Magna Graecia, Campus Universitario Germaneto, Viale Europa, Catanzaro 88100, Italy
| | - M Trotta
- The Institute of Neurology, Department of Medical Sciences, University Magna Graecia, Campus Universitario Germaneto, Viale Europa, Catanzaro 88100, Italy
| | - G Barbagallo
- The Institute of Neurology, Department of Medical Sciences, University Magna Graecia, Campus Universitario Germaneto, Viale Europa, Catanzaro 88100, Italy
| | - G Arabia
- The Institute of Neurology, Department of Medical Sciences, University Magna Graecia, Campus Universitario Germaneto, Viale Europa, Catanzaro 88100, Italy
| | - A Quattrone
- The Institute of Neurology, Department of Medical Sciences, University Magna Graecia, Campus Universitario Germaneto, Viale Europa, Catanzaro 88100, Italy; Neuroimaging Research Unit, Catanzaro, Italy.
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Sun QJ, Chum JM, Bautista TG, Pilowsky PM, Berkowitz RG. Neuronal mechanisms underlying the laryngeal adductor reflex. Ann Otol Rhinol Laryngol 2012; 120:755-60. [PMID: 22224318 DOI: 10.1177/000348941112001110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Electromyographic studies of the laryngeal adductor reflex, glottal closure occurring in response to laryngeal stimulation, have demonstrated an early ipsilateral response (R1) and a late bilateral response (R2). To better define the physiologic properties of these responses, we recorded responses from expiratory laryngeal motoneurons (ELMs) in rats during stimulation of the superior laryngeal nerve (SLN). METHODS Single unit extracellular recordings were obtained from 5 ELMs, identified by their antidromic responses to recurrent laryngeal nerve stimulation and postinspiratory firing pattern, in 4 Sprague-Dawley rats. RESULTS Unilateral stimulation of the SLN (at 20 Hz) stopped both phrenic nerve inspiratory activity and ELM postinspiratory activity. However, the ELMs displayed robust tonic firing, consisting of non-respiratory burst activity and single action potentials. The single action potentials were identified as short-latency ones (5 to 10 ms) activated by ipsilateral SLN stimulation, with an occurrence rate of 90%, and long-latency ones (20 to 50 ms) activated by bilateral SLN stimulation, with occurrence rates of 47% on the ipsilateral side and 58% on the contralateral side. CONCLUSIONS The R1 response appears to be the result of the short-latency action potentials, orthodromically activated by ipsilateral stimulation of the SLN. The R2 response is likely to be a result of the long-latency action potentials that can be recorded from ELMs on both sides.
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Affiliation(s)
- Qi-Jian Sun
- Australian School of Advanced Medicine, Macquarie University, Sydney, Australia
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Ludlow CL, Adler CH, Berke GS, Bielamowicz SA, Blitzer A, Bressman SB, Hallett M, Jinnah HA, Juergens U, Martin SB, Perlmutter JS, Sapienza C, Singleton A, Tanner CM, Woodson GE. Research priorities in spasmodic dysphonia. Otolaryngol Head Neck Surg 2008; 139:495-505. [PMID: 18922334 DOI: 10.1016/j.otohns.2008.05.624] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 05/02/2008] [Accepted: 05/28/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To identify research priorities to increase understanding of the pathogenesis, diagnosis, and improved treatment of spasmodic dysphonia. STUDY DESIGN AND SETTING A multidisciplinary working group was formed that included both scientists and clinicians from multiple disciplines (otolaryngology, neurology, speech pathology, genetics, and neuroscience) to review currently available information on spasmodic dysphonia and to identify research priorities. RESULTS Operational definitions for spasmodic dysphonia at different levels of certainty were recommended for diagnosis and recommendations made for a multicenter multidisciplinary validation study. CONCLUSIONS The highest priority is to characterize the disorder and identify risk factors that may contribute to its onset. Future research should compare and contrast spasmodic dysphonia with other forms of focal dystonia. Development of animal models is recommended to explore hypotheses related to pathogenesis. Improved understanding of the pathophysiology of spasmodic dysphonia should provide the basis for developing new treatment options and exploratory clinical trials. SIGNIFICANCE This document should foster future research to improve the care of patients with this chronic debilitating voice and speech disorder by otolaryngology, neurology, and speech pathology.
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Affiliation(s)
- Christy L Ludlow
- Laryngeal and Speech Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
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Andrade CRFD, Sassi FC, Juste F, Mendonça LIZD. Persistent developmental stuttering as a cortical-subcortical dysfunction: evidence from muscle activation. ARQUIVOS DE NEURO-PSIQUIATRIA 2008; 66:659-64. [DOI: 10.1590/s0004-282x2008000500010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 07/17/2008] [Indexed: 11/22/2022]
Abstract
BACKGROUND: One contemporary view of stuttering posits that speech disfluencies arise from anomalous speech motor control. PURPOSE: To verify the rest muscle tension and speech reaction time of fluent and stuttering adults. METHOD: 22 adults, divided in two groups: G1 - 11 fluent individuals; G2 - 11 stutterers. Electromyography recordings (inferior orbicularis oris) were collected in two different situations: during rest and in a reaction time activity. RESULTS: The groups were significantly different considering rest muscle tension (G2 higher recordings) and did not differ when considering speech reaction time and muscle activity during speech. There was a strong positive correlation between speech reaction time and speech muscle activity for G2 - the longer the speech reaction time, the higher the muscle activity during speech. CONCLUSION: In addition to perceptible episodes of speech disfluency, stutterers exhibit anomalies in speech motor output during fluent speech. Correlations with a possible cortical-subcortical disorder are discussed.
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Abstract
Cervical dystonia, the most common focal dystonia, frequently results in cervical pain and disability as well as impairments affecting postural control. The predominant treatment for cervical dystonia is provided by physicians, and treatment can vary from pharmacological to surgical. Little literature examining more conservative approaches, such as physical therapy, exists. This article reviews the etiology and pathophysiology of the disease as well as medical and physical therapist management for people with cervical dystonia.
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Affiliation(s)
- Beth E Crowner
- Program in Physical Therapy, Washington University School of Medicine, 4444 Forest Park Blvd, Campus Box 8502, St Louis, MO 63108, USA.
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Abstract
Dystonia is a disorder of involuntary sustained muscle contractions. It is commonly classified by age of onset, distribution of involved body regions, and etiology. The pathophysiolgy of this condition is complex and imperfectly understood. This article reviews the epidemiology, genetics, clinical features, and approach to diagnosis and treatment of dystonia.
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Affiliation(s)
- Ninith Kartha
- Department of Neurology, University of Michigan Medical Center, 1500 Medical Center Drive, 1324 Taubman Center, Ann Arbor, MI 48109-0322, USA
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Ali SO, Thomassen M, Schulz GM, Hosey LA, Varga M, Ludlow CL, Braun AR. Alterations in CNS activity induced by botulinum toxin treatment in spasmodic dysphonia: an H215O PET study. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2006; 49:1127-46. [PMID: 17077220 DOI: 10.1044/1092-4388(2006/081)] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Speech-related changes in regional cerebral blood flow (rCBF) were measured using H(2)(15)O positron-emission tomography in 9 adults with adductor spasmodic dysphonia (ADSD) before and after botulinum toxin (BTX) injection and 10 age- and gender-matched volunteers without neurological disorders. Scans were acquired at rest and during production of continuous narrative speech and whispered speech. Speech was recorded during scan acquisition for offline quantification of voice breaks, pitch breaks, and percentage aperiodicity to assess correlations between treatment-related changes in rCBF and clinical improvement. Results demonstrated that speech-related responses in heteromodal sensory areas were significantly reduced in persons with ADSD, compared with volunteers, before the administration of BTX. Three to 4 weeks after BTX injection, speech-related responses were significantly augmented in these regions and in left hemisphere motor areas commonly associated with oral-laryngeal motor control. This pattern of responses was most strongly correlated with the objective measures of clinical improvement (decreases in the frequency of voice breaks, pitch breaks, and percentage aperiodicity). These data suggest a pathophysiological model for ADSD in which BTX treatment results in more efficient cortical processing of sensory information, making this information available to motor areas that use it to more effectively regulate laryngeal movements.
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Affiliation(s)
- S Omar Ali
- Language Section, Voice, Speech and Language Branch, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 10, Room 8S235A, 10 Center Drive, Bethesda, MD 20892, USA
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17
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Affiliation(s)
- Gregory A Grillone
- Department of Otolaryngology-Head and Neck Surgery, Boston University Medical Center, 88 East Newton Street, D-608, Boston, MA 02118, USA.
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Erickson ML. Effects of voicing and syntactic complexity on sign expression in adductor spasmodic dysphonia. AMERICAN JOURNAL OF SPEECH-LANGUAGE PATHOLOGY 2003; 12:416-424. [PMID: 14658993 DOI: 10.1044/1058-0360(2003/087)] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Clients with adductor spasmodic dysphonia (ADSD) tend to exhibit inter- and intraclient variability of signs and symptoms. This variability may result in inaccurate assessment of severity. Accurate assessment of severity requires knowledge concerning the factors that affect the expression of ADSD signs and symptoms. This study examined ADSD sign expression as a function of voicing and syntactic complexity. Fifteen ADSD participants and 15 control participants completed a task consisting of 30 sentences. ADSD signs were significantly more frequent in predominantly voiced sentences than in predominantly voiceless sentences, regardless of level of syntactic complexity. Center-embedded sentences comprising predominantly voiced consonants were found to evoke the greatest number of ADSD signs. These results have important implications for the assessment of ADSD.
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Affiliation(s)
- Molly L Erickson
- Audiology and Speech Pathology, University of Tennessee, 578 South Stadium Hall, Knoxville, TN 37996, USA.
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Abstract
Childhood dystonias are a heterogeneous group of disorders with strong inherited basis. This review describes the clinical characteristics, classification, genetic basis, pathophysiology, biochemistry, pathology, and treatment of dystonias, including the primary dystonias, the dystonia-plus syndromes, secondary dystonias, and heredodegenerative disorders. Conditions discussed in detail include idiopathic torsion dystonia, dopa-responsive dystonia, Wilson's disease, myoclonus dystonia, rapid-onset dystonia parkinsonism, neurodegeneration with brain iron accumulation (Hallervorden-Spatz syndrome), mitochondrial dystonias, Niemann-Pick type C, and neuroacanthocytosis.
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Affiliation(s)
- Ergun Y Uc
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52246, USA
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20
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Sabbahi M, Etnyre B, Al-Jawayed I, Jankovic J. Soleus H-reflex measures in patients with focal and generalized dystonia. Clin Neurophysiol 2003; 114:288-94. [PMID: 12559236 DOI: 10.1016/s1388-2457(02)00375-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The purpose of this study was to examine neurophysiological characteristics of dystonia patients using electromyographic soleus H-reflex methods. METHODS Thirty normal healthy individuals were compared to 27 patients with focal (cervical) or generalized dystonia. Three H-reflex assessment methods were included: the ratio of maximum H-reflex to direct muscle potential (H/M ratio); vibration inhibition (H(v)/H(c) ratio); and H-reflex recovery curves (HRRC). RESULTS Average H/M ratios between groups were not statistically significant. The average H(v)/H(c) ratio for the generalized dystonia group was significantly greater than the focal dystonia and normal groups. Average values of the HRRC showed the generalized dystonia group had significantly greater disinhibition than the focal dystonia and control groups during the early inhibition phase. The HRRC for the focal dystonia group was greater than normal and more similar to the generalized dystonia group during the late phases of the recovery curve. The average value of the localized late facilitation phase for the focal dystonia group was significantly greater than the control group and less than the generalized dystonia group. No differences were observed between groups for the average localized late inhibition phase of the recovery curve. CONCLUSIONS Soleus H-reflex measures identified neurophysiologic differences between generalized dystonia, cervical dystonia and normal conditions. SIGNIFICANCE This methodology enables analysis of the underlying characteristics of dystonic pathologies using soleus H-reflex methods rather than upper extremity H-reflex techniques.
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21
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Abstract
Transcranial magnetic stimulation (TMS) is a safe, noninvasive, and painless way to stimulate the human motor cortex in behaving human subjects. When it is applied as a single-pulse, measurements such as central conduction time, motor threshold, silent-period duration, recruitment curve, and mapping of muscle representation can be determined. Paired-pulse TMS is a useful way to examine cortical excitability. Single and paired-pulse TMS have been applied to study plasticity following amputation and cortical excitability in patients with dystonia. Another form of TMS is repetitive TMS (rTMS), with stimuli delivered repeatedly to a single scalp site. High-frequency rTMS can be used to transiently inactivate different cortical areas to study their functions. rTMS can also modulate cortical excitability. At stimulus frequencies higher than 5 Hz, rTMS increases cortical excitability, and stimulation around 1 Hz reduces cortical excitability. Modulation of cortical excitability by rTMS has therapeutic potential in psychiatric and neurological disorders.
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Affiliation(s)
- R Chen
- Division of Neurology and Playfair Neuroscience Unit, Toronto Western Research Institute, University of Toronto, Toronto, Ontario, Canada.
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22
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Galardi G, Volonté MA, Maderna L, Amadio S, Nemni R, Comi G. Oculomotor focal dystonia. Mov Disord 2001; 16:366-70. [PMID: 11295800 DOI: 10.1002/mds.1052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- G Galardi
- Department of Neuroscience, San Raffaele Scientific Institute, Milan, Italy.
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Deleyiannis FW, Gillespie M, Bielamowicz S, Yamashita T, Ludlow CL. Laryngeal long latency response conditioning in abductor spasmodic dysphonia. Ann Otol Rhinol Laryngol 1999; 108:612-9. [PMID: 10378532 DOI: 10.1177/000348949910800615] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previously, we demonstrated that patients with adductor spasmodic dysphonia (ADSD) have a disinhibition of laryngeal responses to sensory input. In this study, sensorimotor responses to stimulation of the superior laryngeal nerve were compared between 10 subjects with abductor spasmodic dysphonia (ABSD) and 15 normal volunteers. The groups had similar latency and frequency characteristics of their unconditioned adductor responses (p>.05). The conditioned R1 (early) responses of the subjects with ABSD were greater and more variable in amplitude than those of the normal volunteers (p< or =.008). Similar R2 (late) conditioning effects were found in both groups, with a nonsignificant trend toward reduced inhibition of contralateral R2 responses at lower interstimulus intervals (p = .01) in the patient group. Thus, inhibitory mechanisms that modulate the R1 laryngeal sensorimotor pathway in the brain stem may be abnormal in subjects with ABSD. Abnormal modulation of laryngeal sensorimotor responses seems present in both types of spasmodic dysphonia.
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Affiliation(s)
- F W Deleyiannis
- Voice and Speech Section, Division of Intramural Research, National Institute on Deafness and Other Communication Disorders, Bethesda, Maryland 20892-1416, USA
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24
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Syed NA, Delgado A, Sandbrink F, Schulman AE, Hallett M, Floeter MK. Blink reflex recovery in facial weakness: an electrophysiologic study of adaptive changes. Neurology 1999; 52:834-8. [PMID: 10078735 DOI: 10.1212/wnl.52.4.834] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To study the electrophysiologic effects of unilateral facial weakness on the excitability of the neuronal circuitry underlying blink reflex, and to localize the site of changes in blink reflex excitability that occur after facial weakness. BACKGROUND Eyelid kinematic studies suggest that adaptive modification of the blink reflex occurs after facial weakness. Such adaptations generally optimize eye closure. A report of blepharospasm following Bell's palsy suggests that dysfunctional adaptive changes can also occur. METHODS Blink reflex recovery was evaluated with paired stimulation of the supraorbital nerve at different interstimulus intervals. Comparisons were made between normal control subjects and patients with Bell's palsy who either recovered facial strength or who had persistent weakness. RESULTS Blink reflex recovery was enhanced in patients with residual weakness but not in patients who recovered facial strength. Facial muscles on weak and unaffected sides showed enhancement. In patients with residual weakness, earlier blink reflex recovery occurred when stimulating the supraorbital nerve on the weak side. Sensory thresholds were symmetric. CONCLUSION Enhancement of blink reflex recovery is dependent on ongoing facial weakness. Faster recovery when stimulating the supraorbital nerve on the paretic side suggests that sensitization may be lateralized, and suggests a role for abnormal afferent input in maintaining sensitization. Interneurons in the blink reflex pathway are the best candidates for the locus of this plasticity.
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Affiliation(s)
- N A Syed
- Neurology Section, The Aga Khan University, Karachi, Pakistan
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25
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Abstract
The blink reflex (BR) is a generalised phenomenon in mammals. Its teleological protective eye function is perhaps the reason why the BR can be provoked by a multitude of stimuli. As corneal and glabellar reflexes, BR has an inveterate use in the neurological exploration. Some of its physiopathological aspects were discussed more than 100 years ago, and soon half a century will have passed since the first electrophysiological study was published. This review focuses on the BR elicited by the electrical stimulation of the trigeminal supraorbital nerve, a controlled and reliable model in clinical neurophysiology. The electrically elicited BR is an exteroceptive-nociceptive reflex recorded on the orbicularis oculi muscle and formed by three components: the two principal ones, R1 and R2, of well-known characteristics, and a third, R3, of increasing interest, to which there is wide mention. The trigeminal afferent limb reaches the facial efferent one by means of a long and quite complex central pathway located at the brainstem bulbopontine level. The anatomical substrate and criteria of the rich topographical lesional semiology of the BR are established. The importance of the suprasegmental influences upon the reflex, coming mainly from the cerebral cortex and basal ganglia, as well as the impairment caused by their damage, will be emphasised. Special attention is paid to the relationship between the reflex and the dopaminergic system, and the consequences of its derangement. The methods of habituation and suppression-recovery of the BR are extensively and critically reviewed. These methods measure its excitability and serve in practice for the pathophysiological study of numerous diseases. The relationship of the BR with the spontaneous blinking is considered, and the existence of a primary inhibitory reflex on levator palpebrae muscles, previous to the active reflex response of the orbicularis, is proposed. The electrophysiological characteristics of the glabellar reflex, the corneal reflex, the acoustic, photic and somatosensory provoked BR, the ontogeny, and some of the common factors influencing the reflex, such as sleep, are also discussed. The strategic position of the neural structures of the BR, in an area involved in the gating of the various sensory-motor systems and the relative ease to its evaluation with common methodology used in clinical neurophysiology, makes the BR an essential tool for the diagnosis and pathophysiological insight into an important number of human neurological disorders.
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Affiliation(s)
- A Esteban
- Department of Clinical Neurophysiology, Hospital General Universitario Gregorio Marañón, Madrid, Spain
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26
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Abstract
Many different disorders have dystonia as the only or primary sign. The list of causes for dystonia increases yearly and now includes three mapped loci for primary torsion dystonia, although other susceptibility genes are suspected. Study of one of these primary torsion dystonia loci (DYT1) has culminated in the cloning of a gene which codes for a novel protein, torsin A. Physiological and positron emission tomography analyses suggest that dystonia results from impaired inhibition at cortical and subcortical levels; these physiological changes may in turn be due to striatal dysfunction and a mismatch or imbalance between the direct and indirect pathways. Future study of normal and mutant torsin A, as well as the identification of other primary torsion dystonia genes, should help elucidate the mechanisms underlying dystonia.
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Affiliation(s)
- S B Bressman
- Albert Einstein College of Medicine and Beth Israel Medical Center, New York, USA
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27
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Briellmann RS, Rösler KM, Hess CW. Blink reflex excitability is abnormal in patients with periodic leg movements in sleep. Mov Disord 1996; 11:710-4. [PMID: 8914098 DOI: 10.1002/mds.870110617] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The excitability of the late component of the blink reflex was measured in 19 patients with periodic leg movements in sleep (PLMS) and in 18 control patients with other sleep complaints. PLMS patients were not different from controls regarding age, body mass index, and apneas and hypopneas per hour of sleep. The latencies of the R1 and R2 components of the blink reflex were not different between the groups. However, in PLMS, the excitability of the R2 response was markedly enhanced: The second R2 response to a pair of stimuli given at an interval of 500 ms was in PLMS 59.5% (range 21-87%) of the first R2 response and in controls 18.8% (range 2-79%) (p < 0.0001, Mann-Whitney U test). These results provide further evidence of an altered motor control in PLMS, which is likely to be located subcortically and possibly related to the dopaminergic striatopallidal system.
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Affiliation(s)
- R S Briellmann
- Department of Neurology, University of Bern, Switzerland
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28
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Eekhof JL, Aramideh M, Bour LJ, Hilgevoord AA, Speelman HD, Ongerboer de Visser BW. Blink reflex recovery curves in blepharospasm, torticollis spasmodica, and hemifacial spasm. Muscle Nerve 1996; 19:10-5. [PMID: 8538655 DOI: 10.1002/(sici)1097-4598(199601)19:1<10::aid-mus2>3.0.co;2-b] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
R1 and R2 blink reflex responses to single and paired stimuli were investigated in 23 control subjects, 21 patients with blepharospasm (BSP), 20 patients with torticollis spasmodica (TS), and 23 with hemifacial spasm (HFS). For paired stimuli, we compared measurements of area and peak responses at two and three times R2 threshold. R1 and R2 indices were calculated as the average of the recovery values at 0.5-, 0.3-, and 0.21-s interstimulus intervals to test individual patients. Peak amplitude measurements at three times R2 threshold were optimal. The R2 index was abnormal in 67% of BSP patients, 37% of TS patients, and 50% of HFS patients on the affected side and 20% on the unaffected side. A normal R2 index in one third of patients with BSP may indicate that different pathophysiological mechanisms are involved in this type of focal dystonia.
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Affiliation(s)
- J L Eekhof
- Graduate School Neurosciences Amsterdam, AZUA, Department of Neurology, The Netherlands
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30
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Ludlow CL, Schulz GM, Yamashita T, Deleyiannis FW. Abnormalities in long latency responses to superior laryngeal nerve stimulation in adductor spasmodic dysphonia. Ann Otol Rhinol Laryngol 1995; 104:928-35. [PMID: 7492063 DOI: 10.1177/000348949510401203] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Sensorimotor responses to repeated electrical stimulation of the superior laryngeal nerve were compared in 8 patients with adductor spasmodic dysphonia (ADSD) and 11 normal controls to determine if adductor response disinhibition occurred in ADSD. Pairs of electrical pulses were presented at interstimulus intervals varying from 100 to 5,000 milliseconds (ms). Three responses were measured in thyroarytenoid muscles: ipsilateral R1 responses at 17 ms and ipsilateral and contralateral R2 responses between 60 and 75 ms. Conditioned response characteristics, the percent occurrence and percentage amplitude of initial responses, were measures of response inhibition. As a group, the patients had reduced response inhibition: their conditioned ipsilateral R1 response amplitudes were increased, as was the frequency of their conditioned contralateral muscle responses (p < or = .002) compared to normal. However, the patients' initial responses were normal in latency and frequency characteristics, demonstrating that the brain stem mechanisms for these responses were intact. These results suggest a central disinhibition of laryngeal responses to sensory input in ADSD.
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Affiliation(s)
- C L Ludlow
- Voice and Speech Section, National Institute on Deafness and Other Communication Disorders, Bethesda, Maryland 20892-1416, USA
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31
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Deuschl G, Toro C, Matsumoto J, Hallett M. Movement-related cortical potentials in writer's cramp. Ann Neurol 1995; 38:862-8. [PMID: 8526458 DOI: 10.1002/ana.410380606] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Movement-related cortical potentials in response to simple, self-paced, brisk index finger abduction movements were recorded in patients with simple and complex writer's cramp and compared with those of age-matched control subjects. Analysis of the movement-related cortical potential waveforms showed that the Bereitschaftspotential, the peak of the negative slope, and the frontal peak of the motor potential did not differ in the two groups, except for the average amplitude of the early part of the negative-slope peak, which was decreased in the patient group during the interval of 300 to 200 msec prior to electromyographic onset. This finding was restricted to the electrodes overlying the contralateral and midline central electrodes. Movement-related cortical potentials from patients and control subjects could be equally accounted for by a four-dipole source model with sources located in the contralateral and ipsilateral sensorimotor regions and the supplementary motor area. There was a trend for a reduction in the strength of the sensorimotor sources active during the premotor period in the patient group, but the difference did not reach a significant level for any individual source. No differences were found between the movement-related cortical potentials elicited by movements of the affected and unaffected hand, or between those of patients with simple or complex hand cramps. This result suggests a deficiency of contralateral motor cortex activation just prior to the initiation of voluntary movements in patients with focal dystonia.
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Affiliation(s)
- G Deuschl
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1428, USA
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32
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Jääskeläinen SK. Electrophysiological study of blink reflex in humans: differences in mental and supraorbital nerves. ACTA PHYSIOLOGICA SCANDINAVICA 1995; 154:143-50. [PMID: 7572210 DOI: 10.1111/j.1748-1716.1995.tb09896.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In order to find an explanation for the discrepancy between previous reports on the consistency of the blink reflex response with stimulation of the mental nerve, the habituation of the blink reflex was studied with stimulation of the supraorbital and mental nerves in 14 healthy adults. A series of eight electrical stimuli was delivered to the distributions of the nerves on each side at frequency rates of 1.0, 0.5, 0.2 and 0.1 Hz. The latencies and peak-to-peak amplitudes of the ipsilateral late blink reflex components (R2i) were measured. The habituation phenomenon was analysed by means of multivariate analysis of the amplitudes, the nerve and frequency effects were determined by means of a repeated measures analysis of variance model. The blink reflex showed more pronounced amplitude attenuation of the consecutive responses with stimulation of the mental than the supraorbital nerve at rates of 0.5 and 0.2 Hz, and marginally so also at 0.1 Hz. For the supraorbital nerve, habituation could be demonstrated with stimulation frequencies of 1.0 and 0.5 Hz, while for the mental nerve a statistically significant habituation phenomenon was found even with the lowest repetition rate of 0.1 Hz. The greater tendency of the mental nerve blink reflex to habituate is obviously one reason why it has previously sometimes been considered too inconsistent to be useful in clinical practice. For the recording of the supraorbital nerve blink reflex, a 10 s interval between stimuli is adequate, whereas longer interstimulus intervals may have to be adopted to obtain consistent blink reflex responses with stimulation of the mental nerve.
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Affiliation(s)
- S K Jääskeläinen
- Department of Clinical Neurophysiology, University Central Hospital, Turku, Finland
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Hallett M, Berardelli A, Delwaide P, Freund HJ, Kimura J, Lücking C, Rothwell JC, Shahani BT, Yanagisawa N. Central EMG and tests of motor control. Report of an IFCN committee. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1994; 90:404-32. [PMID: 7515784 DOI: 10.1016/0013-4694(94)90132-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M Hallett
- National Institutes of Health, NINDS, Bethesda, MD 20892
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Abstract
The pathophysiology of the movement disorders arising from basal ganglia disorders has been uncertain, in part because of a lack of a good theory of how the basal ganglia contribute to normal voluntary movement. An hypothesis for basal ganglia function is proposed here based on recent advances in anatomy and physiology. Briefly, the model proposes that the purpose of the basal ganglia circuits is to select and inhibit specific motor synergies to carry out a desired action. The direct pathway is to select and the indirect pathway is to inhibit these synergies. The clinical and physiological features of Parkinson's disease, L-DOPA dyskinesias. Huntington's disease, dystonia and tic are reviewed. An explanation of these features is put forward based upon the model.
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Affiliation(s)
- M Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
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Abstract
In order to assess the clinical utility of trigemino-facial reflexes in lower facial muscles, we studied perioral reflexes to mechanical and electrical stimulation in 13 patients with spasmodic dysphonia and orofacial dyskinesia and in 7 healthy subjects. Mechanical stimulation of the upper lip of all patients and electrical stimulation of the infraorbital nerve of patients with orofacial dyskinesia elicited larger perioral reflexes than in controls. In the majority of patients, hyperexcitable perioral reflexes were accompanied by increased gain of the blink reflex. In 4 patients, however, trigemino-facial reflexes were enhanced selectively in either the perioral muscles or orbicularis oculi. Our findings suggest that the quantitative assessment of perioral reflexes may provide information about the excitability of brainstem interneurons in cranial dystonia that is complementary to blink reflex studies.
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Affiliation(s)
- H Topka
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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Reilly JA, Hallett M, Cohen LG, Tarkka IM, Dang N. The N30 component of somatosensory evoked potentials in patients with dystonia. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1992; 84:243-7. [PMID: 1375883 DOI: 10.1016/0168-5597(92)90005-v] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We recorded short-latency median nerve somatosensory evoked potentials (SEPs) in 10 patients with dystonia (6 with focal dystonia, 3 with generalized dystonia, and 1 with segmental dystonia) and compared them with those of 10 normal controls. The EEG was recorded from 29 sites on the scalp with linked earlobe electrodes for reference. Latencies and amplitudes of P15, postcentral N20 and P45, and frontal N30 were evaluated. The latencies of all potentials were the same in patients and controls. The amplitudes of P15, N20 and P45 were also the same in both groups, but the N30 amplitude of the patients was larger than of the controls. The amplitude of N30 did not vary from the affected side to the unaffected side. Previous work has shown decreased N30 amplitude in patients with Parkinson's disease. Changes in N30 amplitude may be indicative of abnormal excitatory effects on cortex resulting from disorders of the basal ganglia.
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Affiliation(s)
- J A Reilly
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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Schaefer SD, Roark RM, Watson BC, Kondraske GV, Freeman FJ, Butsch RW, Pohl J. Multichannel electromyographic observations in spasmodic dysphonia patients and normal control subjects. Ann Otol Rhinol Laryngol 1992; 101:67-75. [PMID: 1728888 DOI: 10.1177/000348949210100116] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Spasmodic dysphonia is primarily a disorder of vocalization. Increasing evidence, however, suggests that individuals with this disorder comprise a heterogeneous population characterized by abnormal motor control throughout the vocal tract. Multichannel simultaneous electromyography was performed on 11 spasmodic dysphonia patients and 10 normal awake subjects to investigate both the distribution of neuromotor abnormality within the vocal tract (eg, intrinsic and extrinsic laryngeal muscles, tongue, and palate) and the contribution of activation of higher central nervous system centers to observed abnormality. Experimental tasks ranged from vegetative (quiet breathing) to simple linguistic (short sentences). Digitized electromyographic signals were analyzed to compute the amplitude envelope and extract a set of parameters that represent amplitude characteristics. Electrode insertions were cross-validated by quantitative analysis of patterns of activation across selected reference tasks and by traditional qualitative methods. Between-group differences were found for measures of normalized median and peak token amplitudes. These differences are both task- and measure-dependent. Results highlight the complex and interactive effects of muscle, task, and quantitative measures on between-group differences.
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Affiliation(s)
- S D Schaefer
- Department of Otolaryngology, University of Texas Southwestern Medical Center, Dallas
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Hanson DG, Logemann JA, Hain T. Differential diagnosis of spasmodic dysphonia: A kinematic perspective. J Voice 1992. [DOI: 10.1016/s0892-1997(05)80029-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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