Bilateral ballism: a rare syndrome. Review of the literature and presentation of a case.

Ballism rarely occurs as a bilateral phenomenon and only 12 such cases have been reported so far in the literature. A further case is reported in the present paper. The definition of bilateral ballism is discussed, its movements described and the differences from chorea outlined. The most important difference from hemiballism is in the pathological substrate where, in most bilateral cases, diffuse lesions have been reported on both sides of the basal ganglia, without preferential involvement of the subthalamic nucleus. In our case, a fronto-temporal infarction was found. In the cases reported to date, the outcome had varied from death to complete recovery, partly depending on the aetiology, which is most frequently vascular. Although relevant data are scarce, dopamine antagonists appear to be the treatment of choice. We stress the role of the dopaminergic system and co-existing factors influencing the abnormal involuntary movements.