 |
 |
Surgery for Parkinson's disease carries neuropsychologic risks WESTPORT, Jul 29 (Reuters) - Unilateral posteroventral pallidotomy for the treatment of Parkinson's disease is sometimes associated with modest cognitive impairment and behavioral changes, Canadian researchers warn in the July issue of Neurology. Dr. Lisa L. Trepanier, of The Toronto Hospital-Western Division, in Ontario, Canada, with colleagues there and elsewhere, studied 42 patients with advanced Parkinson's disease who had "...substantial disability because of frequent 'off' periods or drug-induced dyskinesias." Twenty-four patients underwent posteroventral stereotactic pallidotomy on the right hemisphere of the brain and 18 patients on the left side of the brain. Before surgery and 3, 6 and/or 12 months afterward, each patient completed a battery of neuropsychologic tests. As a group, the patients showed improvements in attention and concentration by 6 months after surgery compared with their preoperative test scores, Dr. Trepanier's team reports. Their working-memory capacity declined, however. Conditional associative learning, a measure of frontal executive function, was not affected. Among patients who had undergone left-sided pallidotomies, the team found that verbal learning was impaired in 60% at the time of the first follow-up examination, 3 or 6 months after surgery. Verbal fluency had also declined significantly. Most patients with impaired verbal learning showed no improvement during the study period, and none regained their initial ability. In contrast, verbal learning significantly improved in 44% of right-pallidotomy patients, the investigators determined. Right-hemisphere pallidotomies impaired visuospatial constructional ability, but all except one patient recovered this ability completely within 12 months after surgery. In 25% to 30% of the patients, pallidotomy "...resulted in poorer frontal executive behavioral control (eg, environmental dependency, lack of insight, lability, depression, poor judgment, impulsiveness, obsessive-compulsive behavior)," the Toronto researchers report. "For some patients, these problems negatively affected their relationship with caregivers, especially when they lacked awareness of their deficits or when altered judgment and increased emotional lability were present," the authors note. "These difficulties also restricted proper functioning at work or in social settings, depending on the patients' circumstances." Dr. Trepanier's group recommends that "...the neurologic benefits of unilateral pallidotomy...be weighed against modest cognitive and behavioral risks." Neurology 1998;51:207-215. -- Judith Richards, London, Ontario, Canada [log in to unmask]