There has been a resurgence in the use of
neurosurgical procedures for the treatment of
Parkinson's disease (PD).
Pallidotomy has become a widely performed procedure on the basis of reports which describe marked reduction of
levodopa-induced
dyskinesias and variable improvement in
parkinsonism. Preliminary reports of the effects of globus pallidus internus (GPi) and subthalamic nucleus (STN)
deep brain stimulation (DBS) have also been promising. At 6-month follow up, a cohort of our first 40 patients undergoing
pallidotomy demonstrated the following mean improvements when examined after
drug withdrawal (off) and under optimal medication (on): total motor off scores-31%; total off
activities of daily living scores-30%; and total on
dyskinesias-63% (contralateral and ipsilateral
dyskinesias improved 82% and 50%, respectively). Although improvements in contralateral
dyskinesias and total off
parkinsonism were sustained at 2-year follow up (N = 11), benefit for ipsilateral
dyskinesias was lost after 1-year follow up (N = 24). and postural stability and gait improvements lasted only 3-6 months. On-period,
levodopa-resistant symptoms did not benefit from
pallidotomy. Mean improvements in 8 patients undergoing GPi DBS (4 unilateral and 4 bilateral) at 3 months were as follows: total motor off scores-27%; total off
activities of daily living scores-26%; and total on
dyskinesias-60%. At most recent follow up, 6 patients with STN DBS (5 bilateral and 1 unilateral) showed the following mean improvements: total motor off scores-41%; total motor on scores-27%; total off
activities of daily living scores-40%; and total on
dyskinesias 41%.
Pallidotomy reduces
dyskinesias and off disability. GPi DBS may have effects similar to
pallidotomy, but might be safer when bilateral procedures are required. Bilateral STN DBS may improve off
parkinsonism more than other procedures and might also improve on-period motor function. A randomized trial will be required to determine which procedure is most effective for patients with different clinical features.