Hemiballism-hemichorea from marked hypotension during spinal anesthesia.

Hemiballism and hemichorea following anesthesia-induced hypotension has rarely been described, but a recent case suggests an association. After experiencing marked hypotension during spinal anesthesia, a 70-year-old woman developed hemiballism and hemichorea. Involuntary ballistic movements with writhing, consisting of repetitive rotation and flexion-extension without apparent muscle weakness, affected her left limbs proximally. Low-amplitude, involuntary, choreiform movements involved the distal portions of these limbs. Magnetic resonance imaging demonstrated an area of high signal intensity in the contralateral subthalamic nucleus, suggestive of a focal ischemic lesion. Although such occurrences are rare, anesthesiologists should be aware of the risk of subthalamic nucleus ischemia following marked hypotension.