Ictal (99m)Tc ECD SPECT in paroxysmal kinesigenic choreoathetosis.

Paroxysmal kinesigenic choreoathetosis is a rare neurologic disorder characterized by sudden attacks of brief involuntary dyskinetic movement that are precipitated by voluntary movement. A 14-year-old male who presented with frequent brief attacks of hemidystonia triggered by sudden movement is reported. Investigations, including video electroencephalogram and magnetic resonance imaging of brain, were normal. There was excellent and sustained response to carbamazepine. Ictal single-photon emission computed tomography using (99m)Tc ethyl cysteinate dimer revealed increased perfusion of the contralateral basal ganglia, which is associated with onset of choreoathetosis attacks. Our findings provide evidence that hyperactivity of the basal ganglia is associated with the dyskinetic attacks in paroxysmal kinesigenic choreoathetosis.