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Corniello C, Dono F, Evangelista G, Consoli S, De Angelis S, Cipollone S, Liviello D, Polito G, Melchiorre S, Russo M, Granzotto A, Anzellotti F, Onofrj M, Thomas A, Sensi SL. Diagnosis and treatment of late-onset myoclonic epilepsy in Down syndrome (LOMEDS): A systematic review with individual patients' data analysis. Seizure 2023; 109:62-67. [PMID: 37267668 DOI: 10.1016/j.seizure.2023.05.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 05/18/2023] [Accepted: 05/20/2023] [Indexed: 06/04/2023] Open
Abstract
INTRODUCTION The late onset myoclonic epilepsy in Down Syndrome (LOMEDS) is a peculiar epilepsy type characterized by cortical myoclonus and generalized tonic-clonic seizures (GTCS), in people suffering from cognitive decline in Down syndrome (DS). In this review, we analyzed available data on the diagnostic and therapeutic management of individuals with LOMEDS. METHODS We performed a systematic search of the literature to identify the diagnostic and therapeutic management of patients with LOMEDS. The following databases were used: PubMed, Google Scholar, EMBASE, CrossRef. The protocol was registered on PROSPERO (registration code: CRD42023390748). RESULTS Data from 46 patients were included. DS was diagnosed according to the patient's clinical and genetic characteristics. Diagnosis of Alzheimer's dementia (AD) preceded the onset of epilepsy in all cases. Both myoclonic seizures (MS) and generalized tonic-clonic seizures (GTCS) were reported, the latter preceding the onset of MS in 28 cases. EEG was performed in 45 patients, showing diffuse theta/delta slowing with superimposed generalized spike-and-wave or polyspike-and-wave. A diffuse cortical atrophy was detected in 34 patients on neuroimaging. Twenty-seven patients were treated with antiseizure medication (ASM) monotherapy, with reduced seizure frequency in 17 patients. Levetiracetam and valproic acid were the most used ASMs. Up to 41% of patients were unresponsive to first-line treatment and needed adjunctive therapy for seizure control. CONCLUSIONS AD-related pathological changes in the brain may play a role in LOMEDS onset, although the mechanism underlying this phenomenon is still unknown. EEG remains the most relevant investigation to be performed. A significant percentage of patients developed a first-line ASM refractory epilepsy. ASMs which modulate the glutamatergic system may represent a good therapeutic option.
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Affiliation(s)
- Clarissa Corniello
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy
| | - Fedele Dono
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy.
| | - Giacomo Evangelista
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy
| | - Stefano Consoli
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy
| | - Sibilla De Angelis
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy
| | - Sara Cipollone
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy
| | - Davide Liviello
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Epilepsy Center, "SS Annunziata" Hospital, Chieti, Italy
| | - Gaetano Polito
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Sara Melchiorre
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy
| | - Mirella Russo
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy
| | - Alberto Granzotto
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy
| | | | - Marco Onofrj
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy
| | - Astrid Thomas
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy
| | - Stefano L Sensi
- Department of Neuroscience, Imaging and Clinical Science, "G. d'Annunzio" University of Chieti-Pescara, Chieti, Italy; Behavioral Neurology and Molecular Neurology Units, Center for Advanced Studies and Technology - CAST, University "G. d'Annunzio" of Chieti-Pescara, Italy; Institute for Advanced Biomedical Technologies, University of Chieti-Pescara, Chieti, Italy
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Wang G, Song Y, Su J, Fan Z, Xu L, Fang P, Liu C, Long H, Hu C, Zhou L, Huang S, Zhou P, Wang K, Pang N, Shen H, Li S, Hu D, Xiao B, Zeng LL, Long L. Altered cerebellar-motor loop in benign adult familial myoclonic epilepsy type 1: The structural basis of cortical tremor. Epilepsia 2022; 63:3192-3203. [PMID: 36196770 DOI: 10.1111/epi.17430] [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: 07/13/2022] [Revised: 10/01/2022] [Accepted: 10/03/2022] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Cortical tremor/myoclonus is the hallmark feature of benign adult familial myoclonic epilepsy (BAFME), the mechanism of which remains elusive. A hypothesis is that a defective control in the preexisting cerebellar-motor loop drives cortical tremor. Meanwhile, the basal ganglia system might also participate in BAFME. This study aimed to discover the structural basis of cortical tremor/myoclonus in BAFME. METHODS Nineteen patients with BAFME type 1 (BAFME1) and 30 matched healthy controls underwent T1-weighted and diffusion tensor imaging scans. FreeSurfer and spatially unbiased infratentorial template (SUIT) toolboxes were utilized to assess the motor cortex and the cerebellum. Probabilistic tractography was generated for two fibers to test the hypothesis: the dentato-thalamo-(M1) (primary motor cortex) and globus pallidus internus (GPi)-thalamic projections. Average fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) of each tract were extracted. RESULTS Cerebellar atrophy and dentate nucleus alteration were observed in the patients. In addition, patients with BAFME1 exhibited reduced AD and FA in the left and right dentato-thalamo-M1 nondecussating fibers, respectively false discovery rate (FDR) correction q < .05. Cerebellar projections showed negative correlations with somatosensory-evoked potential P25-N33 amplitude and were independent of disease duration and medication. BAFME1 patients also had increased FA and decreased MD in the left GPi-thalamic projection. Higher FA and lower RD in the right GPi-thalamic projection were also observed (FDR q < .05). SIGNIFICANCE The present findings support the hypothesis that the cerebello-thalamo-M1 loop might be the structural basis of cortical tremor in BAFME1. The basal ganglia system also participates in BAFME1 and probably serves a regulatory role.
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Affiliation(s)
- Ge Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Yanmin Song
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Department of Emergency, Xiangya Hospital, Central South University, Changsha, China
| | - Jianpo Su
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, China
| | - Zhipeng Fan
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, China
| | - Lin Xu
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Peng Fang
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, China.,Department of Military Medical Psychology, Air Force Medical University, Xian, China
| | - Chaorong Liu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Hongyu Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Chongyu Hu
- Department of Neurology, Hunan People's Hospital, Changsha, China
| | - Luo Zhou
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Sha Huang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Pinting Zhou
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Kangrun Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Nan Pang
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Department of Pediatric, Xiangya Hospital, Central South University, Changsha, China
| | - Hui Shen
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, China
| | - Shuyu Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Dewen Hu
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Ling-Li Zeng
- College of Intelligence Science and Technology, National University of Defense Technology, Changsha, China
| | - Lili Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
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Matsubara T, Ahlfors SP, Mima T, Hagiwara K, Shigeto H, Tobimatsu S, Goto Y, Stufflebeam S. Bilateral Representation of Sensorimotor Responses in Benign Adult Familial Myoclonus Epilepsy: An MEG Study. Front Neurol 2021; 12:759866. [PMID: 34764933 PMCID: PMC8577121 DOI: 10.3389/fneur.2021.759866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 09/21/2021] [Indexed: 12/03/2022] Open
Abstract
Patients with cortical reflex myoclonus manifest typical neurophysiologic characteristics due to primary sensorimotor cortex (S1/M1) hyperexcitability, namely, contralateral giant somatosensory-evoked potentials/fields and a C-reflex (CR) in the stimulated arm. Some patients show a CR in both arms in response to unilateral stimulation, with about 10-ms delay in the non-stimulated compared with the stimulated arm. This bilateral C-reflex (BCR) may reflect strong involvement of bilateral S1/M1. However, the significance and exact pathophysiology of BCR within 50 ms are yet to be established because it is difficult to identify a true ipsilateral response in the presence of the giant component in the contralateral hemisphere. We hypothesized that in patients with BCR, bilateral S1/M1 activity will be detected using MEG source localization and interhemispheric connectivity will be stronger than in healthy controls (HCs) between S1/M1 cortices. We recruited five patients with cortical reflex myoclonus with BCR and 15 HCs. All patients had benign adult familial myoclonus epilepsy. The median nerve was electrically stimulated unilaterally. Ipsilateral activity was investigated in functional regions of interest that were determined by the N20m response to contralateral stimulation. Functional connectivity was investigated using weighted phase-lag index (wPLI) in the time-frequency window of 30–50 ms and 30–100 Hz. Among seven of the 10 arms of the patients who showed BCR, the average onset-to-onset delay between the stimulated and the non-stimulated arm was 8.4 ms. Ipsilateral S1/M1 activity was prominent in patients. The average time difference between bilateral cortical activities was 9.4 ms. The average wPLI was significantly higher in the patients compared with HCs in specific cortico-cortical connections. These connections included precentral-precentral, postcentral-precentral, inferior parietal (IP)-precentral, and IP-postcentral cortices interhemispherically (contralateral region-ipsilateral region), and precentral-IP and postcentral-IP intrahemispherically (contralateral region-contralateral region). The ipsilateral response in patients with BCR may be a pathologically enhanced motor response homologous to the giant component, which was too weak to be reliably detected in HCs. Bilateral representation of sensorimotor responses is associated with disinhibition of the transcallosal inhibitory pathway within homologous motor cortices, which is mediated by the IP. IP may play a role in suppressing the inappropriate movements seen in cortical myoclonus.
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Affiliation(s)
- Teppei Matsubara
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan.,International University of Health and Welfare, Otawara, Japan
| | - Seppo P Ahlfors
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States
| | - Tatsuya Mima
- Graduate School of Core Ethics and Frontier Sciences, Ritsumeikan University, Kyoto, Japan
| | - Koichi Hagiwara
- Epilepsy and Sleep Center, Fukuoka Sanno Hospital, Fukuoka, Japan
| | - Hiroshi Shigeto
- Division of Medical Technology, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shozo Tobimatsu
- Department of Orthoptics, Faculty of Medicine, Fukuoka International University of Health and Welfare, Fukuoka, Japan
| | - Yoshinobu Goto
- Department of Physiology, School of Medicine, International University of Health and Welfare, Okawa, Japan
| | - Steven Stufflebeam
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States.,Harvard Medical School, Boston, MA, United States
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4
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Chandarana M, Saraf U, Divya KP, Krishnan S, Kishore A. Myoclonus- A Review. Ann Indian Acad Neurol 2021; 24:327-338. [PMID: 34446993 PMCID: PMC8370153 DOI: 10.4103/aian.aian_1180_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 11/29/2020] [Accepted: 12/09/2020] [Indexed: 11/19/2022] Open
Abstract
Myoclonus is a hyperkinetic movement disorder characterized by a sudden, brief, involuntary jerk. Positive myoclonus is caused by abrupt muscle contractions, while negative myoclonus by sudden cessation of ongoing muscular contractions. Myoclonus can be classified in various ways according to body distribution, relation to activity, neurophysiology, and etiology. The neurophysiological classification of myoclonus by means of electrophysiological tests is helpful in guiding the best therapeutic strategy. Given the diverse etiologies of myoclonus, a thorough history and detailed physical examination are key to the evaluation of myoclonus. These along with basic laboratory testing and neurophysiological studies help in narrowing down the clinical possibilities. Though symptomatic treatment is required in the majority of cases, treatment of the underlying etiology should be the primary aim whenever possible. Symptomatic treatment is often not satisfactory, and a combination of different drugs is often required to control the myoclonus. This review addresses the etiology, classification, clinical approach, and management of myoclonus.
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Affiliation(s)
- Mitesh Chandarana
- Comprehensive Care Centre for Movement Disorders, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | - Udit Saraf
- Comprehensive Care Centre for Movement Disorders, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | - K P Divya
- Comprehensive Care Centre for Movement Disorders, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | - Syam Krishnan
- Comprehensive Care Centre for Movement Disorders, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
| | - Asha Kishore
- Comprehensive Care Centre for Movement Disorders, Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
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Swinkin E, Lizárraga KJ, Algarni M, Garcia Dominguez L, Baarbé JK, Saravanamuttu J, Chen R, Slow E, Lang AE, Wennberg RA. A Distinct EEG Marker of Celiac Disease-Related Cortical Myoclonus. Mov Disord 2020; 36:999-1005. [PMID: 33251639 DOI: 10.1002/mds.28407] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 10/26/2020] [Accepted: 10/30/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Celiac disease is associated with motor cortex hyperexcitability and neurological manifestations including cortical myoclonus. Electroencephalography abnormalities have been described, but no distinct pattern has been reported. METHODS We describe the neurophysiological characteristics of 3 patients with celiac-associated cortical myoclonus using electroencephalography, magnetoencephalography, and transcranial magnetic stimulation. RESULTS Electroencephalography in all cases demonstrated lateralized low-amplitude, electropositive beta-frequency polyspike activity over the central head region, corresponding to motor cortex contralateral to the myoclonic limb. Jerk-locked back-averaging demonstrated a preceding cortical potential; magnetoencephalography source localization revealed a cortical generator in the posterior wall of the precentral gyrus for the back-averaged potential and oscillatory abnormality. In 1 patient, cerebellar inhibition of the motor cortex was physiologically normal. CONCLUSIONS Central head oscillatory, low-amplitude, electropositive electroencephalography polyspike activity may be a distinct marker of celiac-related cortical myoclonus and is consistent with celiac-related motor cortex hyperexcitability, which may not necessarily result from cerebellar disinhibition. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Emily Swinkin
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital and Division of Neurology, UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada
| | - Karlo J Lizárraga
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital and Division of Neurology, UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada.,Motor Physiology and Neuromodulation Program, Division of Movement Disorders and Center for Health and Technology (CHeT), Department of Neurology, University of Rochester, Rochester, New York, USA
| | - Musleh Algarni
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital and Division of Neurology, UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada.,Division of Neurology, East Jeddah Hospital, Jeddah, Saudi Arabia
| | - Luis Garcia Dominguez
- Mitchell Goldhar MEG Unit, Clinical Neurophysiology Laboratory, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Julianne K Baarbé
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, School of Graduate Studies, University of Toronto, Toronto, Ontario, Canada
| | - James Saravanamuttu
- Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Robert Chen
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital and Division of Neurology, UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada.,Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Elizabeth Slow
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital and Division of Neurology, UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada
| | - Anthony E Lang
- Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital and Division of Neurology, UHN, Division of Neurology, University of Toronto, Toronto, Ontario, Canada.,Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Richard A Wennberg
- Mitchell Goldhar MEG Unit, Clinical Neurophysiology Laboratory, Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada
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Ionotropic Glutamate Receptors in Epilepsy: A Review Focusing on AMPA and NMDA Receptors. Biomolecules 2020; 10:biom10030464. [PMID: 32197322 PMCID: PMC7175173 DOI: 10.3390/biom10030464] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/13/2020] [Accepted: 03/14/2020] [Indexed: 12/22/2022] Open
Abstract
It is widely accepted that glutamate-mediated neuronal hyperexcitation plays a causative role in eliciting seizures. Among glutamate receptors, the roles of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors in physiological and pathological conditions represent major clinical research targets. It is well known that agonists of NMDA or AMPA receptors can elicit seizures in animal or human subjects, while antagonists have been shown to inhibit seizures in animal models, suggesting a potential role for NMDA and AMPA receptor antagonists in anti-seizure drug development. Several such drugs have been evaluated in clinical studies; however, the majority, mainly NMDA-receptor antagonists, failed to demonstrate adequate efficacy and safety for therapeutic use, and only an AMPA-receptor antagonist, perampanel, has been approved for the treatment of some forms of epilepsy. These results suggest that a misunderstanding of the role of each glutamate receptor in the ictogenic process may underlie the failure of these drugs to demonstrate clinical efficacy and safety. Accumulating knowledge of both NMDA and AMPA receptors, including pathological gene mutations, roles in autoimmune epilepsy, and evidence from drug-discovery research and pharmacological studies, may provide valuable information enabling the roles of both receptors in ictogenesis to be reconsidered. This review aimed to integrate information from several studies in order to further elucidate the specific roles of NMDA and AMPA receptors in epilepsy.
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Oi K, Neshige S, Hitomi T, Kobayashi K, Tojima M, Matsuhashi M, Shimotake A, Fujii D, Matsumoto R, Kasama S, Kanda M, Wada Y, Maruyama H, Takahashi R, Ikeda A. Low-dose perampanel improves refractory cortical myoclonus by the dispersed and suppressed paroxysmal depolarization shifts in the sensorimotor cortex. Clin Neurophysiol 2019; 130:1804-1812. [PMID: 31401489 DOI: 10.1016/j.clinph.2019.07.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/31/2019] [Accepted: 07/09/2019] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To elucidate the effects of perampanel (PER) on refractory cortical myoclonus for dose, etiology and somatosensory-evoked potential (SEP) findings. METHODS We examined 18 epilepsy patients with seizure and cortical myoclonus. Based on data accumulated before and after PER treatment, correlations among clinical scores in myoclonus and activities of daily life (ADL); early cortical components of SEP; and PER blood concentration, were analyzed. RESULTS PER (mean dose: 3.2 ± 2.1 mg/day) significantly improved seizures, myoclonus and ADL and significantly decreased the amplitude of and prolonged latency of giant SEP components. The degree of P25 and N33 prolongations (23.8 ± 1.6 to 24.7 ± 1.7 ms and 32.1 ± 4.0 to 33.7 ± 3.4 ms) were significantly correlated with improved ADL score (p = 0.019 and p = 0.025) and blood PER concentration (p = 0.011 and p = 0.025), respectively. CONCLUSIONS Low-dose PER markedly improved myoclonus and ADL in patients with refractory cortical myoclonus. Our results suggest that SEP, particularly P25 latency, can be used as a potential biomarker for assessing the objective effects of PER on intractable cortical myoclonus. SIGNIFICANCE In this study, PER lessened the degree of synchronized discharges in the postsynaptic neurons in the primary motor cortex.
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Affiliation(s)
- Kazuki Oi
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan
| | - Shuichiro Neshige
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan; Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical and Health Sciences, Japan; Department of Futaba Emergency General Medicine Supportive Center, Fukushima Medical University, Japan
| | - Takefumi Hitomi
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan; Department of Laboratory Medicine, Kyoto University Graduate School of Medicine, Japan
| | - Katsuya Kobayashi
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan
| | - Maya Tojima
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan
| | - Masao Matsuhashi
- Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan
| | - Akihiro Shimotake
- Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan
| | - Daiki Fujii
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan; Department of Neurology, Kurashiki Central Hospital, Japan
| | - Riki Matsumoto
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan; Department of Neurology, Kobe University Graduate School of Medicine, Japan
| | - Shuhei Kasama
- Department of Neurology, Hyogo College of Medicine, Japan
| | | | - Yoshiaki Wada
- Department of Rehabilitation, Nissan Tamagawa Hospital, Japan
| | - Hirofumi Maruyama
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical and Health Sciences, Japan
| | - Ryosuke Takahashi
- Department of Neurology, Kyoto University Graduate School of Medicine, Japan
| | - Akio Ikeda
- Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Japan.
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Abstract
PURPOSE Benign neonatal sleep myoclonus is a common nonepileptic condition occurring in neurologically normal full-term newborns. During jerks, EEG has always been described as normal. The aim of this study was to describe EEG changes associated with the myoclonic jerks. METHODS Polygraphic video-EEG recordings of four full-term neonates presenting benign neonatal sleep myoclonus were studied. Myoclonic jerks were analyzed regarding their topography, frequency, propagation pattern, and reflex component. EEG averaging time-locked to myoclonic jerks and to somatosensory stimuli (realized by tapping on palms and feet) was performed to study eventual EEG correlates of myoclonus and to asses somatosensory evoked responses-for the latter, two control newborns were added. RESULTS Visual analysis of the EEG disclosed theta band slow waves on central and vertex electrodes concomitant to myoclonic jerks and jerk-locked back-averaging disclosed a sequence of deflections, not preceding, but following the myoclonus. This response predominated on the vertex electrode (CZ) and consisted of five components (N1, P1, N2, P2, and N3), with only the three later components being constantly present (at 110, 200, and 350-500 ms, respectively). Back-averaging locked to the tactile stimuli in four subjects and two control newborns showed similar components and were comparable to those described in the literature as late somatosensory evoked responses in full-term newborns. CONCLUSIONS Myoclonic jerks in benign neonatal sleep myoclonus can evoke visually identifiable EEG potentials on vertex electrodes corresponding to somatosensory responses. This EEG aspect may be misleading and could give rise to an anti-seizure treatment that mostly worsens the condition.
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Nakata H, Namba M, Kakigi R, Shibasaki M. Effects of face/head and whole body cooling during passive heat stress on human somatosensory processing. Am J Physiol Regul Integr Comp Physiol 2017; 312:R996-R1003. [PMID: 28404580 DOI: 10.1152/ajpregu.00039.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/15/2017] [Accepted: 03/30/2017] [Indexed: 11/22/2022]
Abstract
We herein investigated the effects of face/head and whole body cooling during passive heat stress on human somatosensory processing recorded by somatosensory-evoked potentials (SEPs) at C4' and Fz electrodes. Fourteen healthy subjects received a median nerve stimulation at the left wrist. SEPs were recorded at normothermic baseline (Rest), when esophageal temperature had increased by ~1.2°C (heat stress: HS) during passive heating, face/head cooling during passive heating (face/head cooling: FHC), and after HS (whole body cooling: WBC). The latencies and amplitudes of P14, N20, P25, N35, P45, and N60 at C4' and P14, N18, P22, and N30 at Fz were evaluated. Latency indicated speed of the subcortical and cortical somatosensory processing, while amplitude reflected the strength of neural activity. Blood flow in the internal and common carotid arteries (ICA and CCA, respectively) and psychological comfort were recorded in each session. Increases in esophageal temperature due to HS significantly decreased the amplitude of N60, psychological comfort, and ICA blood flow in the HS session, and also shortened the latencies of SEPs (all, P < 0.05). While esophageal temperature remained elevated, FHC recovered the peak amplitude of N60, psychological comfort, and ICA blood flow toward preheat baseline levels as well as WBC. However, the latencies of SEPs did not recover in the FHC and WBC sessions. These results suggest that impaired neural activity in cortical somatosensory processing during passive HS was recovered by FHC, whereas conduction velocity in the ascending somatosensory input was accelerated by increases in body temperature.
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Affiliation(s)
- Hiroki Nakata
- Department of Health Sciences, Faculty of Human Life and Environment, Nara Women's University, Nara, Japan
| | - Mari Namba
- Graduate School of Humanities and Sciences, Nara Women's University, Nara, Japan; and
| | - Ryusuke Kakigi
- Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Manabu Shibasaki
- Department of Health Sciences, Faculty of Human Life and Environment, Nara Women's University, Nara, Japan;
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Ganos C, Kassavetis P, Erro R, Edwards MJ, Rothwell J, Bhatia KP. The role of the cerebellum in the pathogenesis of cortical myoclonus. Mov Disord 2014; 29:437-43. [PMID: 24634361 DOI: 10.1002/mds.25867] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/09/2014] [Accepted: 02/17/2014] [Indexed: 12/26/2022] Open
Abstract
The putative involvement of the cerebellum in the pathogenesis of cortical myoclonic syndromes has been long hypothesized, as neuropathological changes in patients with cortical myoclonus have most commonly been found in the cerebellum rather than in the suspected culprit, the primary somatosensory cortex. A model of increased cortical excitability due to loss of cerebellar inhibitory control via cerebello-thalamo-cortical connections has been proposed, but evidence remains equivocal. Here, we explore this hypothesis by examining syndromes that present with cortical myoclonus and ataxia. We first describe common clinical characteristics and underlying neuropathology. We critically view information on cerebellar physiology with regard to motorcortical output and compare findings between hypothesized and reported neurophysiological changes in conditions with cortical myoclonus and ataxia. We synthesize knowledge and focus on neurochemical changes in these conditions. Finally, we propose that the combination of alterations in inhibitory neurotransmission and the presence of cerebellar pathology are important elements in the pathogenesis of cortical myoclonus.
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Affiliation(s)
- Christos Ganos
- Sobell Department of Motor Neuroscience and Movement Disorders, University College London (UCL) Institute of Neurology, London, United Kingdom; Department of Neurology, University Medical Centre Hamburg-Eppendorf (UKE), Hamburg, Germany; Department of Paediatric and Adult Movement Disorders and Neuropsychiatry, Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
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12
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Kuronen M, Lehesjoki AE, Jalanko A, Cooper JD, Kopra O. Selective spatiotemporal patterns of glial activation and neuron loss in the sensory thalamocortical pathways of neuronal ceroid lipofuscinosis 8 mice. Neurobiol Dis 2012; 47:444-57. [DOI: 10.1016/j.nbd.2012.04.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 04/25/2012] [Accepted: 04/29/2012] [Indexed: 12/16/2022] Open
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13
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Movement preparation and cortical processing of afferent inputs in cortical tremor: An event-related (de)synchronization (ERD/ERS) study. Clin Neurophysiol 2012; 123:1207-15. [DOI: 10.1016/j.clinph.2011.10.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 10/17/2011] [Accepted: 10/29/2011] [Indexed: 11/22/2022]
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14
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Koskenkorva P, Niskanen E, Hyppönen J, Könönen M, Mervaala E, Soininen H, Kälviäinen R, Vanninen R. Sensorimotor, visual, and auditory cortical atrophy in Unverricht-Lundborg disease mapped with cortical thickness analysis. AJNR Am J Neuroradiol 2012; 33:878-83. [PMID: 22268086 DOI: 10.3174/ajnr.a2882] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE EPM1, caused by mutations in the CSTB gene, is the most common form of PME. The most incapacitating symptom of EPM1 is action-activated and stimulus-sensitive myoclonus. The clinical severity of the disease varies considerably among patients, but so far, no correlations have been observed between quantitative structural changes in the brain and clinical parameters such as duration of the disease, age at onset, or myoclonus severity. The aim of this study was to evaluate possible changes in CTH of patients with EPM1 compared with healthy controls and to correlate those changes with clinical parameters. MATERIALS AND METHODS Fifty-three genetically verified patients with EPM1 and 70 healthy volunteers matched for age and sex underwent 1.5T MR imaging. T1-weighted 3D images were analyzed with CTH analysis to detect alterations. The patients were clinically evaluated for myoclonus severity by using the UMRS. Higher UMRS scores indicate more severe myoclonus. RESULTS CTH analysis revealed significant thinning of the sensorimotor and visual and auditory cortices of patients with EPM1 compared with healthy controls. CTH was reduced with increasing age in both groups, but in patients, the changes were confined specifically to the aforementioned areas, while in controls, the changes were more diffuse. Duration of the disease and the severity of myoclonus correlated negatively with CTH. CONCLUSIONS Cortical thinning in the sensorimotor areas in EPM1 correlated significantly with the degree of the severity of the myoclonus and is most likely related to the widespread stimulus sensitivity in EPM1.
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Affiliation(s)
- P Koskenkorva
- Department of Clinical Radiology, Kuopio University Hospital, Puijonlaaksontie 2, FIN-70210 Kuopio, Finland.
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Abstract
This review examines some of the advances in understanding myoclonus over the last 25 years. The classification of myoclonus into cortical, brainstem, and spinal forms has been consolidated, each with distinctive clinical characteristics and physiological mechanisms. New genetic causes of myoclonus have been identified, and the molecular basis of several of these conditions has been discovered. It is increasingly apparent that disease of the cerebellum is particularly important in the genesis of cortical reflex myoclonus. However, the precise mechanism and origin of myoclonus in many situations remain uncertain. Effective treatment of myoclonus remains limited, and the challenge lies ahead to develop more therapeutic options.
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Affiliation(s)
- Hiroshi Shibasaki
- Kyoto University Graduate School of Medicine and Takeda General Hospital, Kyoto, Japan
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16
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Shibasaki H. Cortical activities associated with voluntary movements and involuntary movements. Clin Neurophysiol 2011; 123:229-43. [PMID: 21906995 DOI: 10.1016/j.clinph.2011.07.042] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 07/05/2011] [Accepted: 07/25/2011] [Indexed: 12/11/2022]
Abstract
Recent advance in non-invasive techniques including electrophysiology and functional neuroimaging has enabled investigation of control mechanism of voluntary movements and pathophysiology of involuntary movements in human. Epicortical recording with subdural electrodes in epilepsy patients complemented the findings obtained by the non-invasive techniques. Before self-initiated simple movement, activation occurs first in the pre-supplementary motor area (pre-SMA) and SMA proper bilaterally with some somatotopic organisation, and the lateral premotor area (PMA) and primary motor cortex (M1) mainly contralateral to the movement with precise somatotopic organisation. Functional connectivity among cortical areas has been disclosed by cortico-cortical coherence, cortico-cortical evoked potential, and functional MRI. Cortical activities associated with involuntary movements have been studied by jerk-locked back averaging and cortico-muscular coherence. Application of transcranial magnetic stimulation helped clarifying the state of excitability and inhibition in M1. The sensorimotor cortex (S1-M1) was shown to play an important role in generation of cortical myoclonus, essential tremor, Parkinson tremor and focal dystonia. Cortical myoclonus is actively driven by S1-M1 while essential tremor and Parkinson tremor are mediated by S1-M1. 'Negative motor areas' at PMA and pre-SMA and 'inhibitory motor areas' at peri-rolandic cortex might be involved in the control of voluntary movement and generation of negative involuntary movements, respectively.
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Affiliation(s)
- Hiroshi Shibasaki
- Kyoto University Graduate School of Medicine, Shogoin, Sakyo, Kyoto 606-8507, Japan.
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Kobayashi K, Matsumoto R, Kondo T, Kawamata J, Hitomi T, Inouchi M, Matsuhashi M, Takahashi R, Ikeda A. Decreased cortical excitability in Unverricht–Lundborg disease in the long-term follow-up: A consecutive SEP study. Clin Neurophysiol 2011; 122:1617-21. [DOI: 10.1016/j.clinph.2011.01.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 12/02/2010] [Accepted: 01/19/2011] [Indexed: 10/18/2022]
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Papadelis C, Eickhoff SB, Zilles K, Ioannides AA. BA3b and BA1 activate in a serial fashion after median nerve stimulation: direct evidence from combining source analysis of evoked fields and cytoarchitectonic probabilistic maps. Neuroimage 2010; 54:60-73. [PMID: 20691793 DOI: 10.1016/j.neuroimage.2010.07.054] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 07/20/2010] [Accepted: 07/25/2010] [Indexed: 11/24/2022] Open
Abstract
This study combines source analysis imaging data for early somatosensory processing and the probabilistic cytoarchitectonic maps (PCMs). Human somatosensory evoked fields (SEFs) were recorded by stimulating left and right median nerves. Filtering the recorded responses in different frequency ranges identified the most responsive frequency band. The short-latency averaged SEFs were analyzed using a single equivalent current dipole (ECD) model and magnetic field tomography (MFT). The identified foci of activity were superimposed with PCMs. Two major components of opposite polarity were prominent around 21 and 31 ms. A weak component around 25 ms was also identified. For the most responsive frequency band (50-150 Hz) ECD and MFT revealed one focal source at the contralateral Brodmann area 3b (BA3b) at the peak of N20. The component ~25 ms was localised in Brodmann area 1 (BA1) in 50-150 Hz. By using ECD, focal generators around 28-30 ms located initially in BA3b and 2 ms later to BA1. MFT also revealed two focal sources - one in BA3b and one in BA1 for these latencies. Our results provide direct evidence that the earliest cortical response after median nerve stimulation is generated within the contralateral BA3b. BA1 activation few milliseconds later indicates a serial mode of somatosensory processing within cytoarchitectonic SI subdivisions. Analysis of non-invasive magnetoencephalography (MEG) data and the use of PCMs allow unambiguous and quantitative (probabilistic) interpretation of cytoarchitectonic identity of activated areas following median nerve stimulation, even with the simple ECD model, but only when the model fits the data extremely well.
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Affiliation(s)
- Christos Papadelis
- Laboratory for Human Brain Dynamics, Brain Science Institute (BSI), RIKEN, Saitama, Japan.
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20
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Abstract
Myoclonus has now been recognized to have many possible etiologies, anatomical sources, and pathophysiologic features. Classification schemes may be based on clinical syndromes and etiology, neurophysiology properties, or exam findings. In recent years, many myoclonus case reports and short series have been published. However, this article will group new developments into three areas: (1) Myoclonus in parkinsonian disorders, (2) Concepts in myoclonus generation, and (3) Treatment. Current findings do not allow one to conclude whether or how parkinsonism contributes to the myoclonus mechanism in parkinsonian disorders. Therefore, it seems unlikely that the myoclonus in Lewy body disorders is mostly caused by abnormal basal ganglia input to motor areas of the neocortex. The exact source of cortical myoclonus generation is controversial. Increased corticomuscular coherence represents a robust phenomenon that will need to be explained by any model that offers a putative explanation for cortical myoclonus generation. Myoclonus treatment is still limited, and more research on basic mechanisms before truly effective treatment will be available. The best approach for myoclonus is based on the physiological classification of the myoclonus.
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Affiliation(s)
- John N Caviness
- College of Medicine, Department of Neurology, Mayo Clinic, Scottsdale, AZ 85255, USA.
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Shinoura N, Suzuki Y, Yoshida M, Yamada R, Tabei Y, Saito K, Yagi K. Assessment of the corona radiata sensory tract using awake surgery and tractography. J Clin Neurosci 2009; 16:764-70. [PMID: 19303303 DOI: 10.1016/j.jocn.2008.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2008] [Revised: 09/25/2008] [Accepted: 10/04/2008] [Indexed: 10/21/2022]
Abstract
Anatomical localization of brain function can be achieved by functional changes during awake surgery combined with tractography constructed by diffusion tensor imaging studies. We aimed to use these techniques to characterize the sensory tract in the corona radiata in patients with closely associated brain tumors. Of nine patients who had brain tumors in the primary sensory area (S1) and who underwent awake surgery between October 2004 and July 2007, two patients showed deterioration in deep sensation during and after awake surgery. Both of these patients also developed involuntary movements (for patient 1 this was myoclonus of the left hand, while patient 2 experienced unintentional lifting of the arm). In these two patients, tumors were located just beside the sensory tract in the corona radiata of the right hemisphere. In patient 2, Wallerian degeneration of the sensory tract and concomitant deterioration of superficial and deep sensation were observed at 6 months after awake surgery. These results suggest that damage to a closely associated sensory tract in the corona radiata is critical to the development of sensory deficits and involuntary movements. For patients who undergo surgical resection of S1 brain tumors, pre-operative tractography to detect the sensory tract in the corona radiata may allow protection of the sensory tract during awake surgery, thereby preventing post-operative sensory deficits.
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Affiliation(s)
- N Shinoura
- Department of Neurosurgery, Komagome Metropolitan Hospital, and Department of Radiologic Technology, Tokyo Metropolitan University of Health Sciences, 3-18-22 Hon-Komagome, Bunkyo-ku, Tokyo 113-8677, Japan.
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Parasivam S, Cowey M, Day B, Thyagarajan D. A unique case of cortical myoclonus sensitive to visual stimuli in the peripersonal space. Mov Disord 2009; 24:422-5. [PMID: 19084909 DOI: 10.1002/mds.21931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Multimodal representation of peripersonal or near space has been demonstrated in the brain of the nonhuman primate through invasive electrophysiological experiments. Representation of peripersonal space in the human brain has been inferred from extinction experiments and functional imaging studies. We present a unique case of lower limb myoclonus in a patient with common variable immunodeficiency which is sensitive to visual stimuli in the peripersonal space and light touch. This case provides further evidence for near space representation in the human brain. We hypothesize that somatopically organized multimodal areas exist in the human brain which code for peripersonal space.
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Affiliation(s)
- Sharavanan Parasivam
- Department of Neurology, Flinders Medical Centre, Bedford Park, Adelaide, South Australia.
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Hanajima R, Okabe S, Terao Y, Furubayashi T, Arai N, Inomata-Terada S, Hamada M, Yugeta A, Ugawa Y. Difference in intracortical inhibition of the motor cortex between cortical myoclonus and focal hand dystonia. Clin Neurophysiol 2008; 119:1400-7. [DOI: 10.1016/j.clinph.2008.02.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 01/29/2008] [Accepted: 02/15/2008] [Indexed: 11/29/2022]
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Auvin S, Derambure P, Cassim F, Vallée L. Myoclonies et myoclonies épileptiques : orientation diagnostique et connaissances physiopathologiques. Rev Neurol (Paris) 2008; 164:3-11. [DOI: 10.1016/j.neurol.2007.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 08/22/2007] [Indexed: 11/17/2022]
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Houdayer E, Devanne H, Tyvaert L, Defebvre L, Derambure P, Cassim F. Low frequency repetitive transcranial magnetic stimulation over premotor cortex can improve cortical tremor. Clin Neurophysiol 2007; 118:1557-62. [PMID: 17531531 DOI: 10.1016/j.clinph.2007.04.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 04/02/2007] [Accepted: 04/14/2007] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To examine the effects of a 30 min, 1 Hz subthreshold rTMS in a case of cortical tremor which is caused by hyperexcitability of sensorimotor cortex. METHODS Stimulation was applied over primary and, in a second time, over premotor cortex (M1 and PMC, respectively). Tremor was monitored by accelerometers placed on the index fingers of hands outstretched, before and several times after rTMS. Each rTMS session consisted of 1800 pulses delivered at 1 Hz with an intensity of 90% of resting motor threshold. RESULTS PMC but not M1 stimulation led to a decrease of the postural tremor (90% decrease of acceleration total spectral power). This functional benefit was associated to normalization of electrophysiologic parameters (short-interval intracortical inhibition and cortical silent period duration). Moreover, when stimulating PMC during two daily sessions, improvement of the tremor was longer than one day stimulation and this benefit was associated with functional improvement. CONCLUSIONS This study shows that 1 Hz rTMS over premotor cortex can improve cortical tremor. SIGNIFICANCE These results raise the interest of the motor cortical stimulation as a possible therapeutic target for treatment of action tremor.
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Affiliation(s)
- E Houdayer
- Departement de Neurophysiologie Clinique, Hôpital Roger Salengro, Centre Hospitalier Régional Universitaire, EA 2683, CHRU 59037 Lille cedex, France
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Abstract
Myoclonus may be generated by any area in the central nervous system. Finding its generator is helpful in the diagnostic process. Although clinical features have to be carefully analyzed as they may give a first idea, neurophysiologic study of myoclonus provides the most important clues for the determination of the generator. Surface electromyography (EMG) allows analyzing the recruitment order in generalized myoclonus, thereby suggesting either a cortical, brainstem, or spinal origin. It also reveals whether myoclonus is positive (jerks that are caused by muscle activation) or negative (jerks that are caused by brief muscle inhibition). In non-generalized myoclonus the EMG burst duration gives an idea of the level of the generator. Repetitive peripheral nerve stimulation is required to record somatosensory evoked potentials (SEPs) as well as long latency reflexes (LLR), especially the C reflex. The presence of giant cortical SEPs is an indirect argument for cortical myoclonus. Similarly the existence of LLR at rest orientates towards cortical reflex (sensitive to sensory stimuli) myoclonus. Finally EEG-EMG polygraphy is the only test which is able to prove directly the cortical origin of myoclonus. This is the case when focal cortical events precede myoclonus with a fixed delay. These premyoclonic cortical potentials may either be seen directly on raw recordings or require the use of jerk-locked back averaging (JLBA). This technique allows the averaging of the EEG prior to myoclonus onset (as determined by EMG) in order to reveal a premyoclonic spike that otherwise would remain undetected in the global EEG.
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Affiliation(s)
- F Cassim
- Service de neurophysiologie clinique, EA 2683, hôpital Salengro, CHU, 59037 Lille cedex, France.
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Hitomi T, Ikeda A, Matsumoto R, Kinoshita M, Taki J, Usui K, Mikuni N, Nagamine T, Hashimoto N, Shibasaki H, Takahashi R. Generators and temporal succession of giant somatosensory evoked potentials in cortical reflex myoclonus: Epicortical recording from sensorimotor cortex. Clin Neurophysiol 2006; 117:1481-6. [PMID: 16759904 DOI: 10.1016/j.clinph.2006.03.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2005] [Revised: 03/16/2006] [Accepted: 03/29/2006] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To clarify the generator mechanism of giant somatosensory evoked potentials (giant SEPs) and the hyperexcitability of primary somatosensory and motor cortices (SI and MI). METHODS In a patient with intractable focal seizures manifesting cortical reflex myoclonus of the left foot, giant SEPs to left tibial nerve stimulation were epicortically recorded as a part of presurgical evaluation with subdural electrodes. RESULTS In the single pulse SEPs, enlarged P1-N1 components were observed at the foot area of the SI and MI (86.5-258.8 microV, respectively), and the peak latencies were always shorter at SI than at MI by 6 ms. Similar findings were obtained for peroneal and sural nerve stimulation. In the paired pulse SEPs, the second response was less suppressed, as compared to other interstimulus intervals (ISIs), with ISIs of 40 and 200 ms both at SI and MI. CONCLUSIONS In this particular patient, cortical hyperexcitability to somatosensory stimuli seems to originate from SI but subsequently both SI and MI are responsible for the generation of giant SEPs and cortical reflex myoclonus. SIGNIFICANCE Somatosensory and primary motor cortices both generated enhanced early cortical components of SEPs, most likely by enhancing the latter by the former.
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Affiliation(s)
- Takefumi Hitomi
- Department of Neurology, Kyoto University Graduate School of Medicine, and Takeda General Hospital, Kyoto, Japan
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Abstract
As myoclonus is often associated with abnormally increased excitability of cortical structures, electrophysiological studies provide useful information for its diagnosis and classification, and about its generator mechanisms. The electroencephalogram-electromyogram polygraph reveals the most important information about the myoclonus of interest. Jerk-locked back-averaging and evoked potential studies combined with recording of the long-latency, long-loop reflexes are useful to investigate the pathophysiology of myoclonus further, especially that of cortical myoclonus. Recent advances in magnetoencephalography and transcranial magnetic stimulation have contributed significantly to the understanding of some of the cortical mechanisms underlying myoclonus. Elucidation of physiological mechanisms underlying myoclonus in individual patients is important for selecting the most appropriate treatment.
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Affiliation(s)
- Hiroshi Shibasaki
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Building 10, Room 5C432A, Bethesda, MD 20892-1428, USA.
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Caviness JN, Tsuboi Y, Wszolek ZK. Clinical-electrophysiological correlation of tremor and myoclonus in a kindred with the N279K tau mutation. Parkinsonism Relat Disord 2003; 9:151-7. [PMID: 12573870 DOI: 10.1016/s1353-8020(02)00034-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We used electrophysiological methods to study the hyperkinetic movement disorders in a pallido-ponto-nigral degeneration (PPND) family, which harbors the N279K tau gene mutation. Our purpose was to: (1). characterize the tremor patterns, (2). characterize the myoclonus physiology, (3). determine whether electrophysiology can detect abnormalities in asymptomatic cases. In PPND, we found that the activation tremors correlated with a semi-rhythmic 6-10 Hz electromyography (EMG) pattern, and the rest tremors showed a reciprocal 4-6 Hz pattern. At least two different myoclonus physiology patterns exist in PPND, most notably contrasted by the presence or absence of a demonstrable electroencephalography (EEG) correlate. Electrophysiology yielded remarkable findings in those asymptomatic at-risk individuals that carried the N279K tau mutation.
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Affiliation(s)
- John N Caviness
- Department of Neurology, Parkinson's Disease and Movement Disorders Center, Mayo Clinic Scottsdale, 13400 East Shea Boulevard, Scottsdale, AZ 85259, USA.
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Lauronen L, Huttunen J, Kirveskari E, Wikström H, Sainio K, Autti T, Santavuori P. Enlarged SI and SII somatosensory evoked responses in the CLN5 form of neuronal ceroid lipofuscinosis. Clin Neurophysiol 2002; 113:1491-500. [PMID: 12169332 DOI: 10.1016/s1388-2457(02)00200-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To examine in detail the activation of the primary (SI) and secondary (SII) somatosensory cortex in CLN5, the Finnish variant of late infantile neuronal ceroid lipofuscinoses (NCL). METHODS Somatory evoked magnetic fields were recorded with a 122-channel planar gradiometer in response to median nerve stimulation in 5 CLN5 patients (aged 8.8-16.7 years) and in 10 healthy age-matched controls. RESULTS The first two responses from contralateral SI, N20m and P35m, were 6-20 times stronger in the patients than in the controls. The morphology of the subsequent deflections from SI was abnormal in the patients: a prominent N45m was detected, while the normally present P60m deflection was missing. In 4 patients the contra- and in two patients the ipsilateral SII responses were also enlarged. Furthermore, the SII activation was detected at shorter latency in patients than in controls. CONCLUSIONS At SI, CLN5 is associated with a selective enhancement of the early cortical responses. We propose that the enlargement of N20m most likely reflects increased synchronous input from thalamus, whereas the altered morphology of the following responses may reflect defective interneuronal inhibition at the cortex. The enlargement of SII responses shows that the imbalance between excitation and inhibition in CLN5 extends outside the primary somatosensory areas.
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Affiliation(s)
- Leena Lauronen
- Pediatric Neurology, Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
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Roberts TPL, Tran Q, Ferrari P, Berger MS. Increased somatosensory neuromagnetic fields ipsilateral to lesions in neurosurgical patients. Neuroreport 2002; 13:699-702. [PMID: 11973473 DOI: 10.1097/00001756-200204160-00032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This study is aimed to determine whether the presence of a tumor in close proximity to the somatosensory cortex of the post-central gyrus affects the response evoked from such an area by painless tactile stimulation, recorded by MEG. The main finding of this study is that somatosensory evoked field strengths from cortex ipsilateral to and abutting an intracranial tumor are significantly elevated compared with either contralateral control fields, or with somatosensory evoked fields elicited from cortex ipsilateral to, but distant from tumors (typically involving language areas, such as inferior frontal lobe). Biophysical and biochemical explanations implicate hyperactivity of cortical neurons close to the tumor, suggesting a possible role of MEG as a measure of tumor infiltration.
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Affiliation(s)
- Timothy P L Roberts
- Box 0628, Biomagnetic Imaging Laboratory, Department of Radiology, University of California, San Francisco 94143, USA
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Kamada K, Takeuchi F, Harada T, Qiao B, Houkin K, Kuriki S, Iwasaki Y, Mitsumori K. Enhanced late components of AEFs associated with the temporal lobe lesions. Neuroreport 2001; 12:1297-300. [PMID: 11338210 DOI: 10.1097/00001756-200105080-00048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We recorded auditory evoked magnetic fields (AEFs) by presenting pure tone bursts once every 4000 ms in 11 patients with a brain lesion in or in the vicinity of the auditory cortex. AEFs on the damaged side revealed several enhanced deflections in late-latency AEFs (slow AEFs), peaking at approximately 320 (DI), 1030 (D2) and 1600 (D3) ms post-stimulus in eight patients. All the dipoles of slow AEFs were concentrated in the superior temporal regions which were not involved by brain lesions. D1, D2 and D3 dipoles were uniformly upward, downward and upward, respectively. The dipole moment varied from 12 to 122 nAm and had no consistent relationship with latency. This is the first report describing slow AEFs in cases with temporal lobe lesions.
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Affiliation(s)
- K Kamada
- Department of Neurosurgery, School of Medicine, Hokkaido University, Kita-Ku, Kita 15, Nishi-5, Sapporo 060-8638, Japan
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Liepert J, Haueisen J, Hegemann S, Weiller C. Disinhibition of somatosensory and motor cortex in mitochondriopathy without myoclonus. Clin Neurophysiol 2001; 112:917-22. [PMID: 11336909 DOI: 10.1016/s1388-2457(01)00521-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To test electrophysiologically, if patients with mitochondriopathy but without evidence of myocloni have subclinical signs of disinhibition in motor and somatosensory cortices. METHODS Two patients were studied and compared with age-matched control groups. RESULTS In both patients, giant somatosensory evoked potentials after median nerve stimulation and a reduced intracortical inhibition tested by transcranial magnetic stimulation in a paired pulse paradigm indicated a dysfunction of inhibitory circuits in the motor as well as the somatosensory cortex. In addition, the somatosensory evoked 600 Hz activity recorded by magnetoencephalography was abolished. CONCLUSIONS Patients with mitochondriopathy may suffer from a subclinical disturbance of inhibition in the sensorimotor cortex. The loss of 600 Hz activity indicates that these high-frequency oscillations could reflect the activity of inhibitory neurons in the somatosensory cortex.
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Affiliation(s)
- J Liepert
- Department of Neurology, Friedrich Schiller University of Jena, Jena, Germany.
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Hanajima R, Ugawa Y, Okabe S, Yuasa K, Shiio Y, Iwata NK, Kanazawa I. Interhemispheric interaction between the hand motor areas in patients with cortical myoclonus. Clin Neurophysiol 2001; 112:623-6. [PMID: 11275534 DOI: 10.1016/s1388-2457(01)00477-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To study interhemispheric interaction between the hand motor areas of both hemispheres through the corpus callosum in myoclonus epilepsy. SUBJECTS Five patients with benign myoclonus epilepsy and ten age matched normal volunteers. METHODS We studied effects of a medially directed conditioning stimulus over the right hand motor area on responses in the right first dorsal interosseous muscle to a posteriorly directed test stimulus over the left hand motor area. RESULTS In normal subjects, inhibition was evoked at interstimulus intervals (ISIs) of 8-20ms (late inhibition). In contrast, facilitation occurred in patients at ISIs of 4-6ms (early facilitation) with no late inhibition. CONCLUSIONS The lack of late inhibition in the patients is consistent with the idea that cortical inhibitory interneurones are affected in myoclonus epilepsy. We propose that this releases interhemispheric facilitation from powerful surround inhibition. The consequence is a predominant early facilitation between the hemispheres in patients with myoclonus epilepsy.
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Affiliation(s)
- R Hanajima
- Department of Neurology, Division of Neuroscience, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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Abstract
Myoclonus, defined as shock-like involuntary movement, may be physiological or caused by a very wide variety of hereditary and acquired conditions. Because myoclonus can originate from different disorders and lesions affecting quite varied levels of the central and peripheral nervous systems, it represents from many points of view a diagnostic challenge. Moreover, new entities have been recently individualized, such as cortical tremor, which deserve renewed attention. The aim of this review is to propose a rationale for a diagnostic approach based on clinical and electrophysiological grounds. In this setting, we successively address 1) the clinical features allowing a positive diagnosis of myoclonus; 2) the clinical clues to the etiology; 3) the relevance of the clinical context to the diagnosis; and 4) the contribution of neurophysiology. Differentiating myoclonus from tics, spasm, chorea and dystonia can be difficult, and a careful reappraisal of clinical features allowing precise identification is presented. Moreover, the topographical distribution of myoclonus, the temporal pattern of muscle recruitment, the condition of occurrence and the rhythm of the event, may provide clinical clues relevant to the diagnosis. Myoclonus without associated epilepsy, myoclonus with epilepsy, myoclonus with encephalopathy, parkinsonism and/or dementia represent overlapping clinical categories, although they remain useful for the diagnostic approach. Using electrophysiology (including back-averaging EEG, MEG, SEP, C-reflex studies) to determine the origin of myoclonus may not allow us to focus on the underlying condition. Indeed, in many instances, the myoclonus is cortical in origin, but the pathology is found elsewhere.
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Affiliation(s)
- L Vercueil
- Service de neurologie, Hôpitaux universitaires de Grenoble, 38700 La Tronche, France
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Forss N, Sil�n T, Karjalainen T. Lack of activation of human secondary somatosensory cortex in Unverricht-Lundborg type of progressive myoclonus epilepsy. Ann Neurol 2001. [DOI: 10.1002/1531-8249(200101)49:1<90::aid-ana12>3.0.co;2-d] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kakigi R, Hoshiyama M, Shimojo M, Naka D, Yamasaki H, Watanabe S, Xiang J, Maeda K, Lam K, Itomi K, Nakamura A. The somatosensory evoked magnetic fields. Prog Neurobiol 2000; 61:495-523. [PMID: 10748321 DOI: 10.1016/s0301-0082(99)00063-5] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Averaged magnetoencephalography (MEG) following somatosensory stimulation, somatosensory evoked magnetic field(s) (SEF), in humans are reviewed. The equivalent current dipole(s) (ECD) of the primary and the following middle-latency components of SEF following electrical stimulation within 80-100 ms are estimated in area 3b of the primary somatosensory cortex (SI), the posterior bank of the central sulcus, in the hemisphere contralateral to the stimulated site. Their sites are generally compatible with the homunculus which was reported by Penfield using direct cortical stimulation during surgery. SEF to passive finger movement is generated in area 3a or 2 of SI, unlike with electrical stimulation. Long-latency components with peaks of approximately 80-120 ms are recorded in the bilateral hemispheres and their ECD are estimated in the secondary somatosensory cortex (SII) in the bilateral hemispheres. We also summarized (1) the gating effects on SEF by interference tactile stimulation or movement applied to the stimulus site, (2) clinical applications of SEF in the fields of neurosurgery and neurology and (3) cortical plasticity (reorganization) of the SI. SEF specific to painful stimulation is also recorded following painful stimulation by CO(2) laser beam. Pain-specific components are recorded over 150 ms after the stimulus and their ECD are estimated in the bilateral SII and the limbic system. We introduced a newly-developed multi (12)-channel gradiometer system with the smallest and highest quality superconducting quantum interference device (micro-SQUID) available to non-invasively detect the magnetic fields of a human peripheral nerve. Clear nerve action fields (NAFs) were consistently recorded from all subjects.
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Affiliation(s)
- R Kakigi
- Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, Japan.
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Abstract
As myoclonus is often associated with abnormally increased excitability of cortical structures, electrophysiological studies provide useful information for its diagnosis and classification and about its generator mechanisms. The EEG-EMG polygraph provides the most essential information about the myoclonus of interest. Jerk-locked back averaging and evoked potential studies combined with recording of the long latency, long loop reflexes are useful to further investigate the pathophysiology of myoclonus, especially that of cortical myoclonus. A recent advance in magnetoencephalographic techniques has contributed significantly to the elucidation of some of the cortical mechanisms underlying myoclonus. Elucidation of physiological mechanisms underlying myoclonus in each individual patient is important for selecting the most appropriate treatment of choice.
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Affiliation(s)
- H Shibasaki
- Departments of Neurology and Brain Pathophysiology, Kyoto University School of Medicine, Shogoin, Sakyo, Kyoto, 606-8507 Japan
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Nakasato N, Yoshimoto T. Somatosensory, auditory, and visual evoked magnetic fields in patients with brain diseases. J Clin Neurophysiol 2000; 17:201-11. [PMID: 10831111 DOI: 10.1097/00004691-200003000-00009] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The features of somatosensory (SEFs), auditory (AEFs), and visual evoked fields (VEFs) in healthy subjects and patients with brain diseases provide the basis for clinical investigations using magnetoencephalography (MEG). The SEFs provide clinically useful information to identify the central sulcus and somatotopic organization of the primary somatosensory cortex. Localization accuracy of the SEFs can be tested by cortical stimulation during surgery. Functional reorganization suggested by SEF studies must be verified by other modalities. The AEFs can localize the auditory cortex in the bilateral temporal lobes. Separation of bilateral activities is much clearer in AEFs than in auditory evoked potentials. Modulation of the interhemispheric differences of latency, amplitude, and source localization of AEFs can be used to evaluate auditory function in patients with intracranial lesions. Pattern reversal VEFs provide stable localization of the primary visual function. Separation of bihemispherical activities is the advantage of VEFs over visual evoked potentials. Investigation of VEFs provides objective evaluation of visual field deficits such as homonymous or bitemporal hemianopsia in patients with intracranial lesions. Evoked magnetic fields can provide useful diagnostic information. Such clinical findings, in turn, provides the opportunity to test the source estimation accuracy of MEG.
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Affiliation(s)
- N Nakasato
- Department of Neurosurgery, Tohoku University School of Medicine, Sendai, Japan
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Kanda M, Nagamine T, Ikeda A, Ohara S, Kunieda T, Fujiwara N, Yazawa S, Sawamoto N, Matsumoto R, Taki W, Shibasaki H. Primary somatosensory cortex is actively involved in pain processing in human. Brain Res 2000; 853:282-9. [PMID: 10640625 DOI: 10.1016/s0006-8993(99)02274-x] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We recorded somatosensory evoked magnetic fields (SEFs) by a whole head magnetometer to elucidate cortical receptive areas involved in pain processing, focusing on the primary somatosensory cortex (SI), following painful CO(2) laser stimulation of the dorsum of the left hand in 12 healthy human subjects. In seven subjects, three spatially segregated cortical areas (contralateral SI and bilateral second (SII) somatosensory cortices) were simultaneously activated at around 210 ms after the stimulus, suggesting parallel processing of pain information in SI and SII. Equivalent current dipole (ECD) in SI pointed anteriorly in three subjects whereas posteriorly in the remaining four. We also recorded SEFs following electric stimulation of the left median nerve at wrist in three subjects. ECD of CO(2) laser stimulation was located medial-superior to that of electric stimulation in all three subjects. In addition, by direct recording of somatosensory evoked potentials (SEPs) from peri-Rolandic cortex by subdural electrodes in an epilepsy patient, we identified a response to the laser stimulation over the contralateral SI with the peak latency of 220 ms. Its distribution was similar to, but slightly wider than, that of P25 of electric SEPs. Taken together, it is postulated that the pain impulse is received in the crown of the postcentral gyrus in human.
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Affiliation(s)
- M Kanda
- Department of Brain Pathophysiology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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Ashby P, Chen R, Wennberg R, Lozano AM, Lang AE. Cortical reflex myoclonus studied with cortical electrodes. Clin Neurophysiol 1999; 110:1521-30. [PMID: 10479018 DOI: 10.1016/s1388-2457(99)00101-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To study the mechanism of cortical reflex myoclonus. METHODS A patient with stimulus sensitive myoclonus of the left foot had an array of subdural electrodes placed over the right sensorimotor cortex. RESULTS Stimulation through one of the electrodes (contact 13) facilitated leg muscles with the shortest latency and was presumed to lie over the motor cortex. Tibial nerve stimulation evoked a potential with the shortest latency 1 cm further posteriorly (contacts 11-12). These contacts were presumed to lie over the sensory cortex. The potential at 11-12 was followed by a much larger potential that reversed polarity at contact 13. Back averaging from spontaneous myoclonic jerks showed a cortical premovement potential which reversed polarity at contact 13. The threshold for the motor evoked potential in leg muscles evoked by transcranial magnetic stimulation was lower on the affected side. Electrical stimulation through contact 13 produced cortical potentials that could be recorded at adjacent contacts. The combination of a positive potential followed by a negative potential recurred at approximately 35-40 ms intervals, each positive potential generating a myoclonic jerk. Additional waves resembling I waves accompanied only the first positive potential. Surgical removal of the cortex under electrode 13 abolished the myoclonus. CONCLUSIONS The myoclonic jerks arose in the motor cortex. We postulate that there is increased excitability or synchronization of the cortical neurons at that site. The spontaneous, peripherally induced and recurrent cortical potentials and myoclonic jerks can occur without participation of the circuitry of the presumed I waves.
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Affiliation(s)
- P Ashby
- Playfair Neuroscience Unit, Toronto Hospital, Western Division, University of Toronto, Ontario, Canada.
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Tassinari CA, Rubboli G, Shibasaki H. Neurophysiology of positive and negative myoclonus. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1998; 107:181-95. [PMID: 9803948 DOI: 10.1016/s0013-4694(98)00058-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Myoclonus is defined as a sudden, brief, jerky, shock-like, involuntary movement, arising from the central nervous system that can be caused by a muscular contraction, i.e. positive myoclonus, or by an interruption of muscular activity, i.e. negative myoclonus. Myoclonus can characterize a variety of neurological disorders, and often both positive and negative myoclonus can coexist. In this paper, we outline some relevant clinical aspects and neurophysiological features of the different types of myoclonus, with particular emphasis on the physiological findings. Indeed, since most myoclonus depend on enhancement of neuronal activities which are inherently present in normal subjects, electrophysiological studies are useful for elucidating the underlying pathophysiological mechanisms and for establishing the correct diagnosis [corrected].
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Affiliation(s)
- C A Tassinari
- Department of Neurology, University of Bologna, Bellaria Hospital, Italy.
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