Motor impairment on awakening in a patient with an EEG pattern of "unilateral, continuous spikes and waves during slow sleep".

Movement disorders are rarely described in association with the "continuous spikes and waves during slow sleep (CSWS)" EEG pattern. We report the case of a young girl affected by an epileptic encephalopathy who, from the age of seven years and four months, has twice presented a movement disorder affecting the right arm, manifesting on awakening and disappearing by early afternoon. Sleep EEG during these periods showed continuous, high-amplitude, diphasic spikes and slow waves over the left hemisphere. Association of clobazam, valproic acid and, on the second occasion, ethosuccimide led to disappearance of the above-described EEG picture and associated motor symptoms. Neurophysiological investigations excluded other possible aetiologies. In view of this, and of the close relationship between the EEG picture and clinical course, we interpret the patient's impairment as "motor neglect" secondary to the continuous electrical activity recorded during sleep over the left hemisphere and involving the associative areas. This electrical activity in sleep, may be regarded as a "functional lesion" whose clinical consequences can be correlated with the site of the abnormalities.[Published with video sequences].