PALLIDOTOMY INCREASES ACTIVITY OF MOTOR ASSOCIATION CORTEX IN PARKINSONS-DISEASE - A POSITRON EMISSION TOMOGRAPHIC STUDY

Stereotactic posteroventral pallidotomy can improve motor performance in Parkinson's disease. Interruption of inhibitory pallidal projection s to ventrolateral thalamus, components of a cortical-basal ganglia mo tor loop allows for this clinical benefit. We hypothesized that pallid otomy would lead to increased movement related activity in motor corti cal areas receiving projections from ventrolateral thalamus. This was tested in 6 Parkinson's disease patients who underwent stereotactic po steroventral pallidotomy. Each patient was imaged with positron emissi on tomography (PET) measures of regional cerebral blood how (rCBF) dur ing performance of a simple prehension task and at rest. Scans were ac quired before and 17 weeks after surgery. After pallidotomy, movement- related changes of rCBF increased significantly in both the supplement ary motor area (SMA) and premotor cortex but not in primary motor cort ex. The results demonstrate the importance of pallidothalamic circuitr y for regulating volitional movements and confirm that disruption of i nhibitory input to the ventrolateral thalamus can augment movement-rel ated activity in motor association areas.