COGNITIVE FUNCTION IN PATIENTS WITH PARKINSONS-DISEASE UNDERGOING STEREOTAXIC THALAMOTOMY

Objective-To determine whether thalamotomy leads to cognitive disturba nces in patients with Parkinson's disease. Methods-A total of 53 patie nts with Parkinson's disease undergoing stereotaxic ventrolateral thal amotomy for tremor and rigidity were tested for cognitive functions be fore and after surgery. The cognitive functions investigated involved visuospatial perception and memory, verbal memory, attention shift, an d executive functions including set maintenance and shift. A neuropsyc hological test battery was used that contained the Wisconsin card sort ing test, Street completion test, Stroop test, a dichotic memory liste ning test, and a facial recognition test. Results-Clinically, a good o r moderately good effect on parkinsonian symptoms was obtained in 50 p atients. The neuropsychological investigation showed that the patients were impaired compared with healthy age matched control subjects on m ost tests, showing slight improvement postoperatively on verbal memory and visuospatial perception. No major differences were found between tests before and after operation, and there were no significant differ ences between patients undergoing surgery in the right or in the left thalamus. Conclusion-The study indicates that ventrolateral thalamotom y does not reduce the cognitive capacity in this group of patients.