[Myoclonus of focal action and localized hemispheric lesion. A polygraphic and pharmacological study]

Authors report a case of focal action myoclonus due to a localized hemispheric lesion. The woman had cardiac arrest complicated by ischemic stroke involving the left parietal region. Action myoclonus of the inferior right limb was the sole residual complaint, provoked by movement and maintenance of posture. Patient noted that myoclonus was worsened by carbamazepine and vigabatrin. EEG-EMG polygraphic study demonstrated action myoclonus and showed a particular EEG activity consisting in a volley of spikes on the vertex region during the right inferior limb movements. Contralateral movements did not elicit this activity. Pharmacological response to clonazepam, piracetam and alcohol was studied. A marked improvement of myoclonus was obtained with alcohol. Pathophysiology of this exceptional form of cortical action myoclonus is discussed.