OBJECTIVE: To assess the effects of bilateral pallidal deep brain stimulation 
(DBS) on mood and cognitive performance in patients with dystonia before surgery 
(at baseline, while patients received their usual treatment) and 12 months 
postoperatively (while patients received neurostimulation and their medications) 
in a multicenter prospective study.
METHODS: Twenty-two patients with primary generalized dystonia were evaluated 
with tests focused on executive functions. The authors considered the patients' 
severe disability and selected the following tests: Raven Progressive Matrices 
38, Similarities and Arithmetic subtests of the Wechsler Adult Intelligence 
Scale-R, Grober and Buschke, Wisconsin Card Sorting Test (WCST), verbal fluency, 
Trail Making Test, and the Beck Depression Inventory. Median age at surgery was 
30 years (range = 14 to 54 years), median duration of disease was 18.5 years 
(range = 4 to 37 years).
RESULTS: Before surgery, no patients showed cognitive decline or depression. The 
surgical procedure appeared to be benign cognitively. One year after surgery, 
free recall improved. There was a significant reduction in the number of errors 
in the WCST. No behavioral or mood changes were found.
CONCLUSIONS: Bilateral pallidal stimulation has a good benefit-to-risk ratio as 
it did not negatively affect cognitive performance and mood in primary dystonia, 
while a significant motor improvement was obtained. Moreover, a significant mild 
improvement in executive functions was observed, which may have been related 
either to the surgical treatment or to the marked decrease in anticholinergic 
drugs.