"Mu rhythm status" and clinical correlates.

Rolandic mu rhythm is usually limited to brief stretches of 0.5 to 2 sec duration. Two observations of status-like enhancement of mu rhythm have prompted this report. In both cases, 4-hour EEG-Video-Monitoring was used. Clinically, the reported cases differed considerably. Case 1 showed nearly continuous mu activity associated with general motionlessness: akinesia/amimia but without rigidity, caused by frontal lobe impairment due to multiple sclerosis. In Case 2, an impressive mu-status started in drowsiness and was presumably attributable to levitiracetam (which had rendered seizure-free the patient's formerly severe case of temporal lobe epilepsy). Mu rhythm status, thus far, is an unknown EEG entity. It can be caused by impaired fronto-motor input and may also constitute a medication-effect (levitiracetam).