PRESERVED FUNCTION IN BRAIN INVADED BY TUMOR

OBJECTIVE: Intrinsic brain tumors can arise within regions of the cort ex that are essential to language, motor, and somatosensory functions. Although it is commonly thought that such tumors can be safely resect ed, as long as the resection is limited to grossly abnormal cortex, fu nctional mapping of the cerebral cortex during tumor resection does no t support this contention. METHODS: We report our experience with 14 p atients (9 men, 5 women; median age, 43 yr) with intrinsic brain tumor s of varying degrees of malignancy (four glioblastomas multiforme, fou r anaplastic astrocytomas, two anaplastic oligodendrogliomas, one anap lastic mixed glioma, three gangliogliomas). Cortical mapping was perfo rmed either intraoperatively (n = 11) or extraoperatively via intracra nial electrodes (n = 3). RESULTS: Tumors were found to grossly invade functioning cortices (frontal lobe language cortex, four tumors; tempo ral lobe language cortex, five tumors; motor cortex, four tumors; soma tosensory cortex, one tumor). The gross invasion of functional cortex by tumor limited safe resection in all patients. Three patients experi enced transient postoperative deficits caused by the proximity of the resection to functional cortex. One patient suffered a delayed postope rative hemorrhage, with resultant persistent motor aphasia. CONCLUSION : Intrinsic brain tumors grow by infiltration of normal brain. Consequ ently, brain that appears to be abnormal may remain functional, thus p recluding safe tumor resection.