Motor circuitry re-organization after pallidotomy in Parkinson disease: a neurophysiological study of the bereitschaftspotential, contingent negative variation, and N30.

The aim of the study was to evaluate the reorganization changes in the motor circuitry of the basal ganglia following unilateral posteroventral pallidotomy in Parkinson disease (PD) patients using neurophysiological paradigms. Eight advanced PD patients received a neurophysiological battery 2 months prior and 6 months after unilateral pallidotomy. Examinations were all performed in the practically defined "off" situation. Bereitschaftspotential (BP) and N30 were recorded for each hand alternately. Contingent negative variation (CNV) was obtained using a visual Go/no-Go paradigm. ANOVAs (electrode position; surgery) were applied for BP and CNV results. N30 data were analyzed using Wilcoxon matched-pair tests. A significant increase in amplitude of the late component (NS') of the BP was evidenced with patient performing with the hand contralateral to pallidotomy. No significant amplitude differences were found in CNV after surgery in any lead, or in any of the time windows tested. A trend toward significance was observed corresponding to a postsurgical numerical increase in amplitude of the N30 peak in the hand contralateral to pallidotomy. These results suggest that neurophysiological changes after pallidotomy are mainly in the last stages of movement preparation and execution.