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NEUROPSYCHOLOGICAL EVALUATION OF DEEP-BRAIN-STIMULATION OF PATIENTS WITH PARKINSON DISEASE OR ESSENTIAL TREMOR

Fresenborg I, Gruia D and Sander U

The implantation of a deep brain electrode for functional deactivation of the nucleus ventralis intermedius (VIM) results in a suppression of tremor which is the main symptom disease or essential tremor. The permanent activation leads to a deactivation of the neurons due to depolarisation (Pollak et al., 1993).

This elegant but not completely risc-free method is still in an experimental stage. In addition to complications as bleedings and hemiparesis, cognitive impairments have been described.

Reductions of linguistic abilities have been reported especially in cases of implantations in the left cerebral hemisphere.

Since february 1996 deep brain electrode-implantations have been performed in 15 cases in the neurosurgical ward of the Evangelical hospital in Oldenburg. A careful

neuropsychological evaluation was undertaken:

Preoperative an extensive neuropsychological diagnostic examination was performed. This was done to exclude patients with dementia. Additionally the cognitive capacity of the patients has to be determined, because cognitive impairments are described in literature for patients with parkinson disease. Special emphasis was placed on mnestic functions, attention and executive functions such as conzeption-development and "set‑shifting". Postoperative neuropsychological tests were performed to examine the differential effects of the stimulation on the cognitive capacity respectively to detect undesirable side effects for example visual disorders. We do report our first results.