Ballism and the Subthalamic Nucleus (Nucleus Hypothalamicus; Corpus Luysi)

I. GENERAL CONSIDERATIONS Historical Development of Hemiballism. —"Hemiballism" became associated with pathologic changes in the subthalamic nucleus (nucleus hypothalamicus; corpus Luysi) during the decade following 1920 (Jakob,¹Martin,²von Sántha³and Matzdorff⁴). That involuntary movements sometimes appeared after lesions localized in various parts of the brain had long been known. Weir Mitchell⁵and Charcot⁶recognized their frequent unilateral occurrence after apoplexies with the terms "posthemiplegic chorea" and "hemichorea." These terms, with the earlier contribution of "athetosis" by Hammond,⁷generally sufficed to distinguish the types of movements encountered.⁸ In the German literature, the flinging or throwing of the limbs arising from violent involvement of proximal musculature was described under the term "hemiballismus." Thus, Greidenberg⁹commented: The most frequent form of posthemiplegic motor disturbance, and hence the most adequately investigated, is without doubt hemichorea (posthemiplegic or postapoplectic hemichorea,hemichorée posthemiplégique[Charcot], hemikinesia [Hughlings