Motor and cognitive sequelae of unilateral pallidotomy in intractable Parkinson's Disease: electronic measurement of motor steadiness is a useful outcome measure

This study examined the short-term motor and cognitive sequelae of unilateral posterolateral pallidotomy for patients with intractable Parkinson's Disease (PD). Unique to this study was the inclusion of electronic motor steadiness instrumentation among pre- and postsurgical assessment procedures. Fifteen PD patients underwent right-sided surgery and 10 underwent left-sided surgery; patients were evaluated 1 month presurgery and approximately 3 months postsurgery. Motorically, there were no significant changes in grooved pegboard or maze-drawing performances, but patients evidenced significantly improved steadiness, particularly in the hand contralateral to the side of surgery. Cognitively, there were no significant decrements on postsurgery composite variables comprised of well-known tests of attention, executive functioning, delayed memory or recognition memory; these findings were similar for patients with either left- or right-sided surgery. There was, however, a significant change in language abilities among a subset of patients. This change was evident in the decline in verbal fluency in PD patients who underwent left-sided pallidotomy, a finding that has consistently emerged in pallidotomy outcome studies. This decline is discussed in terms of evidence that suggests that the basal ganglia consist of several separate, but parallel circuits, some of which are important for cognition.