Neuronal activity in the globus pallidus in chorea caused by striatal lacunar infarction.

Pallidotomy was performed in a patient with hemichorea caused by lacunar infarction in the striatum. Chorea in the lower limb was reduced after a neurosurgical lesion in the medial portion of the sensorimotor territory of the internal segment of the globus pallidus, and chorea in the upper limb disappeared after an additional lesion in the lateral portion of that same area. Intraoperative neuronal recording revealed that mean firing rates were low, and that firing was irregular in the globus pallidus compared with off-state parkinsonian patients. These results suggest that chorea with striatal infarction is driven by phasic neuronal activity with a low firing rate in the globus pallidus and that the neural pathway of chorea has a functional somatotopical organization in the globus pallidus.