Despite the findings of significantly improved motor functioning following
pallidotomy for the treatment of Parkinson's disease, the cognitive sequela
e following surgery have yet to be clearly defined. With increasing knowled
ge of the surgery's effect on frontostriatal circuits, the cognitive proces
ses potentially affected by the procedure require further exploration to ev
aluate fully the efficacy of the treatment. We reviewed 10 studies on the n
europsychological outcome after pallidotomy that were published in peer-rev
iewed journals, A general agreement exists that pallidotomy is a relatively
safe and effective treatment for ameliorating the motor symptoms of Parkin
son's disease, with relatively few cognitive changes reported following sur
gery. However, a number of conceptual and methodological concerns, includin
g diverse selection criteria, small sample sizes and short follow-up period
s, limit the interpretation and generalizability of these findings. These c
oncerns are discussed in detail, along with a summary of the current neurop
sychological literature, suggested guidelines for the conduct of research a
nd future research directions. The neuropsychological findings are critical
ly reviewed and tabulated by study, cognitive domain and follow-up period,
with particular emphasis on hemisphere-specific cognitive changes.