BRAIN-STEM MYOCLONUS IN A PATIENT WITH NON-DOPA-RESPONSIVE PARKINSONISM

In the few reports where electrophysiologic techniques have been used to characterise stimulus-sensitive myoclonus in the setting of a parki nsonian syndrome, the origin of the myoclonus has usually been found t o be cortical. We describe a patient with parkinsonism unresponsive to levodopa who had myoclonus that was both spontaneous and induced by s omatosensory stimuli. In addition, autonomic symptoms and a marked sle ep disturbance were present early in his illness, Results of electroph ysiologic investigations including electromyography (EMG) studies, rou tine electroencephalography (EEG) recording, jerked locked back-averag ing of EEG, and somatosensory evoked potentials were consistent with a brainstem origin for the myoclonic jerks. Following ipsilateral digit al and supraorbital electrical stimulation, the earliest muscle activa tion occurred in the trapezius. An all-night sleep study showed freque nt myoclonic jerks during sleep and markedly abnormal sleep architectu re. We believe that this patient's myoclonus was related to pathologic changes in brainstem reticular nuclei that occurred as part of his di sease process. To our knowledge, brainstem myoclonus has not been desc ribed as a feature of parkinsonian syndromes.