Psychomotor and executive functioning after unilateral posteroventral pallidotomy in patients with Parkinson's disease

The goal of the study was to explore the immediate effects of unilateral posteroventral stereotactic pallidotomy (PVP) on psychomotor and executive functioning in patients with Parkinson's disease (PD). The original drawing task, conducted on a digitizing tablet, and neuropsychological tests were administered to 25 patients with PD, 2 or 3 days before and after the surgery. To assess executive functions, the following tests were used: Trail Making Test (TMT), Stroop Colour Interference Test and Wisconsin Card Sorting Test (WCST). To evaluate global mental functioning, Mini Mental State Examination (MMSE) was applied. Benton Visual Retention Test (BVRT) was introduced as a control non-executive task. The patients undergoing a surgery were compared with age and education matched healthy and PD controls. PVP resulted in an increased movability of the upper contralateral limbs reflected in larger average pressure put during the drawing task after the surgery. Assessment of the emotional state showed a significant postoperative improvement. An isolated significant decline of WCST performance, not related to the side of the lesion, was observed immediately after the surgery. The performance of the other executive and non-executive tasks remained unchanged. The results showed that unilateral PVP may lead to immediate selective executive impairment and is needed to be explored in further studies.