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

In Parkinson's disease, cognitive performance can vary according to levodopa levels (on-off states). Both positive and negative effects of dopaminergic stimulation have been reported. Pallidotomy is also able to change cognitive 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 performance, and the interaction between surgery and state was significant. In relation to the difference between preoperative and postoperative performance in Trail Making B test, there was a significant postsurgical improvement only in off state. Verbal fluency decreased after pallidotomy in both on and off conditions. Our results suggest that pallidotomy can change the effects of levodopa on neuropsychological functions. (C) 2000 Elsevier Science Ltd. All rights reserved.