Preprogramming motor dysfunction in paroxysmal kinesigenic choreoathetosis.

Paroxysmal kinesigenic choreoathetosis (PKC) is characterized by abnormal involuntary movements precipitated by sudden movement. As a result, a possible impairment of cerebral organization of voluntary motor activity is hypothesized in PKC. We examined a 14-year-old boy affected by a sporadic form of PKC, adopting a multimodal psychophysiological approach, including P300, contingent negative variation (CNV) and a specific paradigm for the study of movement related potentials (MRPs). Recordings were made before and after phenobarbital therapy. No changes were observed in the non-motor parameters (P300 and early wave of the CNV), whereas the premotor CNV component and the electrophysiological components, reflecting the preprogramming activity of a voluntary motor act, showed selective modifications induced by the anticonvulsant therapy. Our PKC patient presents a disorder of temporal organization of a voluntary motor response to a stimulus. Both a clinical improvement and normalization of motor-related electrophysiological anomalies were observed during phenobarbital (PB) therapy.