Influence of internal globus pallidus stimulation on motor cortex activation pattern in Parkinson's disease.

OBJECTIVES

Indications of the functional neurosurgical treatments become more and more numerous, however, few methods were used to study the mechanism of action and some discrepancies came to light. We assessed the influence of internal globus pallidus (GPI) stimulation and L-Dopa on cortical activation during the preparation and execution phases of the movement compared to clinical improvement of Parkinson's disease.

METHODS

We recorded the movement-related cortical potential and movement-related desynchronization.

RESULTS

The Unified Parkinson's Disease Rating Scale was improved by 46% under stimulation and 64% under stimulation with L-Dopa. Premovement desynchronization was significantly increased on central contralateral derivation under stimulation with L-Dopa and decreased on frontocentral ipsilateral derivation under stimulation with and without L-Dopa. Movement desynchronization was improved on the contralateral motor cortex under stimulation with and without L-Dopa (benefit correlated with bradykinesia improvement). The movement-related postmotor potential was significantly increased under stimulation with L-Dopa.

CONCLUSIONS

GPI stimulation alone influenced the premotor cortex activation during the planning and induced a selective and focal effect on the organisation of motor cortical activity during the movement execution which may explain bradykinesia improvement. The motor cortex activation improvement under stimulation with L-Dopa concerned both the movement preparation and execution but remained very localised to the contralateral motor cortex.