Language recovery following subthalamic nucleus stimulation in Parkinson's disease.

Neuropsychological consequences of stimulation of the subthalamic nucleus for treatment of drug-resistant Parkinson's disease (PD) have been studied previously. However, no detailed investigations of linguistic function modifications have been carried out. We studied four consecutive patients with PD who underwent chronic bilateral stimulation of the subthalamic nuclei. Neuropsychological and linguistic evaluations were performed before and 2 weeks after surgery. Linguistic abilities were studied also 1 year after surgery with stimulators both off and on. Intraphrasal hesitation pauses, phonemic paraphasias and morpho-syntactic errors were significantly reduced and lexical retrieval improved with stimulation of the subthalamic nuclei. Implicit linguistic phenomena, mainly occurring within basal ganglia circuitry, benefited by recovery of functional equilibrium within basal nuclei and between overall basal ganglia circuitry and cerebral cortex.