Cognitive function in patients with Parkinson's disease undergoing stereotaxic thalamotomy

To determine whether thalamotomy leads to cognitive disturbances in patients with Parkinson's disease.

A total of 53 patients with Parkinson's disease undergoing stereotaxic ventrolateral thalamotomy for tremor and rigidity were tested for cognitive functions before and after surgery. The cognitive functions investigated involved visuospatial perception and memory. verbal memory, attention shift, and executive functions including set maintenance and shift. A neuropsychological test battery was used that contained the Wisconsin card sorting test, Street completion test, Stroop test, a dichotic memory listening test, and a facial recognition test.

Clinically, a good or moderately good effect on parkinsonian symptoms was obtained in 50 patients. The neuropsychological investigations showed that the patients were impaired compared with healthy age matched control subjects on most 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 differences between patients undergoing surgery in the right or in the left thalamus.

The study indicates that ventrolateral thalamotomy does not reduce the cognitive capacity in this group of patients.