title: Coherence analysis in the myoclonus of corticobasal degeneration.
abstract: We investigated whether myoclonus in corticobasal degeneration (CBD) is cortical or subcortical in origin. Many authors have suggested that the myoclonus in CBD is a subtype of cortical myoclonus, despite the fact that back-averaging fails to detect a cortical correlate to spontaneous or action induced jerks and giant sensory evoked potentials are seldom found. Electroencephalographic-electromyographic (EEG-EMG) and EMG-EMG frequency analysis may be more sensitive to cortical drives when EMG bursts occur at a high frequency and at low amplitudes as in CBD. We evaluated EEG-EMG and EMG-EMG coherence and phase in 5 patients with clinically probable CBD and unilateral, action-induced and stimulus-sensitive myoclonus. We found negligible corticomuscular coherence despite a dramatically exaggerated EMG-EMG coherence. We conclude that an inflated EMG-EMG coherence is found in some patients with CBD and that this is unlikely to be due to an exaggerated cortical drive.
authors.affiliation: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom. p.grosse@ion.ucl.ac.uk
authors.forename: Pascal
authors.initials: P
authors.lastname: Grosse
authors.forename: Andrea
authors.initials: A
authors.lastname: Kühn
authors.forename: Carla
authors.initials: C
authors.lastname: Cordivari
authors.forename: Peter
authors.initials: P
authors.lastname: Brown
mesh_terms: D000368:Aged; D001479:Basal Ganglia / Q000503:physiopathology*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009207:Myoclonus / Q000175:diagnosis* / Q000503:physiopathology*; D009410:Nerve Degeneration / Q000175:diagnosis* / Q000503:physiopathology*