Premium
Pathogenesis of cortical myoclonus studied by magnetoencephalography
Author(s) -
Mima Tatsuya,
Nagamine Takashi,
Ikeda Akio,
Yazawa Shogo,
Kimura Jun,
Shibasaki Hiroshi
Publication year - 1998
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410430507
Subject(s) - precentral gyrus , myoclonus , magnetoencephalography , neuroscience , myoclonic jerk , motor cortex , cortex (anatomy) , psychology , medicine , electroencephalography , magnetic resonance imaging , stimulation , radiology
Myoclonus‐associated cortical activities were studied by simultaneous recording of a magnetoencephalogram and an electroencephalogram in 6 patients with cortical myoclonus due to various causes. Cortical activities were averaged, with respect to the precise onset of the myoclonic jerk, to evaluate the myoclonus‐associated cortical magnetic fields. The estimated generator of their earliest peak was localized at the contralateral precentral gyrus in all patients. As judged from the direction of the electrical current, surface positive activity preceding the electromyographic discharge was detected in 3 patients with cortical reflex myoclonus and in 1 patients with possible corticobasal degeneration. In contrast, in the remaining 2 patients (Lennox‐Gastaut syndrome and Alzheimer's disease), magnetic fields time‐locked to the myoclonic jerk were associated with surface negative activity at the precentral cortex. The present study, applying for the first time an off‐line jerk‐locked back‐averaging analysis to magnetoencephalography, demonstrated the important role of the precentral cortex in generating spontaneous myoclonus. It is most likely that the differing polarity of the electromagnetic activity reflects the differing activation pattern within the cortical laminar structure in the precentral area, underlying the generation of various types of myoclonus.