Patterns of EMG-EMG coherence in limb dystonia.
Dystonia of the limbs may be due to a wide range of aetiologies and may cause major functional limitation. We investigated whether the previously described pathological 4 to 7 Hz drive to muscles in cervical dystonia is present in patients with aetiologically different types of dystonia of the upper and lower limbs. To this end, we studied 12 symptomatic and 4 asymptomatic carriers of the DYT1 gene, 6 patients with symptomatic dystonia due to focal basal ganglia lesions, and 11 patients with fixed dystonia, a condition assumed to be mostly psychogenic in aetiology. We evaluated EMG-EMG coherence in the tibialis anterior (TA) of these and 15 healthy control subjects. Ten of 12 (83%) of symptomatic DYT1 patients had an excessive 4 to 7 Hz common drive to TA, evident as an inflated coherence in this band. This drive also involved the gastrocnemius, leading to co-contracting electromyographic bursts. In contrast, asymptomatic DYT1 carriers, patients with symptomatic dystonia, patients with fixed dystonia, and healthy subjects showed no evidence of such a drive or any other distinguishing electrophysiological feature. Moreover, the pathological 4 to 7 Hz drive in symptomatic DYT1 patients was much less common in the upper limb, where it was only present in 2 of 6 (33%) patients with clinical involvement of the arms. We conclude that the nature of the abnormal drive to dystonic muscles may vary according to the muscles under consideration and, particularly, with aetiology.
Grosse
Pascal
P
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom.|Charité, Campus Virchow-Klinikum, Berlin, Germany.
Edwards
M
M
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom.
Tijssen
M A J
MAJ
Academic Medical Center, Amsterdam, The Netherlands.
Schrag
A
A
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom.
Lees
Andrew J
AJ
National Hospital for Neurology and Neurosurgery, London, United Kingdom.
Bhatia
K P
KP
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom.
Brown
Peter
P
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom.
D000328:Adult; D000868:Anterior Compartment Syndrome / Q000150:complications / Q000503:physiopathology; D018726:Anti-Dyskinesia Agents / Q000627:therapeutic use; D000927:Anticonvulsants / Q000627:therapeutic use; D000978:Antiparkinson Agents / Q000627:therapeutic use; D001480:Basal Ganglia Diseases / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D001905:Botulinum Toxins / Q000627:therapeutic use; D002998:Clonazepam / Q000627:therapeutic use; D004421:Dystonia / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D004576:Electromyography / Q000295:instrumentation / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones / Q000235:genetics; D014282:Trihexyphenidyl / Q000627:therapeutic use
D018726:Anti-Dyskinesia Agents; D000927:Anticonvulsants; D000978:Antiparkinson Agents; D018832:Molecular Chaperones; C108175:TOR1A protein, human; D002998:Clonazepam; D014282:Trihexyphenidyl; D001905:Botulinum Toxins