gms | German Medical Science

Objective: Most neurosurgeons define eloquence of brain areas by relevance for language and motor function without consideration of other brain functions. Higher cognitive functions however, including attention, memory and executive functions, considerably affect patients' quality of life and their ability to cope with daily demands. Still, the influence of brain tumors and its surgical resection on cognitive function remains unknown.

Methods: Thirty-four pts harbouring brain tumors underwent neuropsychological evaluation. Those receiving tumor resection were tested prior to and after surgery. Pts receiving stereotactic tumor biopsy were tested prior to surgery, only. The basic test battery included a Token Test and a Mini-Mental-Status-Test (MMST). An extended test battery was conducted to evaluate attention (TAP, subtests alertness, Go/NoGo and divided attention; d2 test; TMT A), memory (WMS-r, subtests digit and block span forward & backward; VLMT; Rey Osterrieth Complex Figure Test) and executive functions (TMT B, FWIT, RWT). In case of a MMST-score of 18 or below only basic tests were conducted. Moreover, tumor location and entity were assessed.

Results: Mean age was 53 years (18–80), 9 pts had low grade, 18 high grade gliomas, 7 ventricular tumors or metastasis. 26 pts underwent resection, 8 pts stereotactic biopsy. In 6 pts tumor was located parietal, in 14 pts frontal, in 5 temporal. Four ventricular tumors, 3 multilocular without affecting the midline, and one with midline involvement. Pts with lesions of the left hemisphere (n=12) revealed preoperative a lower MMST-score of 24 compared to pts with lesions of the right hemisphere (n=16) of 27 (p<0.1). Likewise, this difference occurred in other subtests with statistical significance (FWIT, p<0.01). In the group undergoing resection a slight deterioration in cognitive function from MMST-score 26 to 24 occurred (n.s.). Pts above 50 years revealed a stronger deterioration of postoperative cognitive function.

Conclusions: Especially lesions of the dominant hemisphere are associated with impairment of cognitive function already prior to surgical resection. Surprisingly, surgery influenced test results only slightly. A follow-up on a larger number of patients is currently being conducted to further define critical brain areas for the maintenance of cognitive function.