MR imaging in "lacunar" hemiballismus.

We compared cranial CT and proton magnetic resonance imaging in two patients with hemiballismus secondary to lacunar infarctions. Magnetic resonance, but not CT, showed lacunar infarctions in the subthalamic nucleus. To confirm the location of the infarctions, we measured the distance of the lacunae from the anteroposterior commissure line in three planes (sagittal, axial, and coronal) and demonstrated that the infarctions were located in the lateral part of the subthalamic nucleus.