Teaching Video NeuroImages: semiology and localization of ballistic movements.

Ballistic chorea (hemichorea–hemiballism) localizes to the subthalamic nucleus and its connections (video 1, figure, Aa) or the putamen (video 2, figure, Ab). Other large-amplitude hyperkinetic lesional movements can have similarly high localizing value. “Ballistic” tremor may develop months after recovering from ventrolateral thalamic strokes, in the thalamogeniculate vascular territory (video 3, figure, Ac and Ad). Similarly, “ballistic dystonia,” limb dystonia with superimposed arrhythmic and jerky movements often referred to as myoclonic dystonia, may develop months after recovering from combined vascular lesions in the striatum and posterior thalamus (video 4, figure, Ae and Af). These motor complications, delayed by hours to days (hemiballism) or weeks to months (ballistic dystonia and tremor), have relatively distinct localization value to a narrow “ballistic corridor” in the basal ganglia and thalamus (figure, B).