Surgical therapy for Parkinson's disease.

High frequency stimulation (HFS) has become the main alternative to medical treatment, due to its reversibility, adaptability, and low morbidity. Initiated in the thalamus (Vim) for the control of tremor, HFS has been applied to the Pallidum (GPi), and then to the subthalamic nucleus (STN), suggested by experiments in MPTP monkeys. STN-HFS is highly efficient on tremor, rigidity and bradykinesia and is now widely applied. Criteria for success are correct patient selection and precise electrode placement. The best outcome predictor is the response to Levodopa. The mechanisms of action might associate inhibition of cell firing, jamming of neuronal message and exhaustion of synaptic neurotransmitter release. The inhibition of glutamate STN release could be neuroprotective on nigral cells. Animal experiments support this hypothesis, not contradicted by the long-term follow up of patients. Neuroprotection might have considerable impact on the management of PD patient and warrants clinical trials.