Effects of unilateral posteroventral pallidotomy on 'on-off' cognitive fluctuations in Parkinson's disease

In Parkinson's disease, cognitive performance can vary according to levodop a levels (on-off states). Both positive and negative effects of dopaminergi c stimulation have been reported. Pallidotomy is also able to change cognit ive performance, in addition to levodopa pharmacokinetics. The: aim of this investigation was to study the effects of pallidotomy on cognitive on-off fluctuations in Parkinson's disease. A brief neuropsychological battery nas administered to 15 PD patients during or? and off states before and after surgery. Before pallidotomy, patients performed better in the on condition on Trail Making test B; after pallidotomy levodopa no longer improved perfo rmance, and the interaction between surgery and state was significant. In r elation to the difference between preoperative and postoperative performanc e in Trail Making B test, there was a significant postsurgical improvement only in off state. Verbal fluency decreased after pallidotomy in both on an d off conditions. Our results suggest that pallidotomy can change the effec ts of levodopa on neuropsychological functions. (C) 2000 Elsevier Science L td. All rights reserved.