Preserving executive functions in nondominant frontal lobe glioma surgery: an intraoperative tool.

OBJECTIVE: The goal of surgery for gliomas is maximal tumor removal while preserving the patient's full functional integrity. At present during frontal tumor removal, this goal is mostly achieved, although the risk of impairing the executive functions (EFs), and thus the quality of life, remains significant. The authors investigated the accuracy of an intraoperative version of the Stroop task (iST), adapted for intraoperative mapping, to detect EF-related brain sites by evaluating the impact of the iST brain mapping on preserving functional integrity following a maximal tumor resection.

METHODS: Forty-five patients with nondominant frontal gliomas underwent awake surgery; brain mapping was used to establish the functional boundaries for the resection. In 18 patients language, praxis, and motor functions, but not EFs (control group), were mapped intraoperatively at the cortical-subcortical level. In 27 patients, in addition to language, praxis, and motor functions, EFs were mapped with the iST at the cortical-subcortical level (Stroop group). In both groups the EF performance was evaluated preoperatively, at 7 days and 3 months after surgery.

RESULTS: The iST was successfully administered in all patients. Consistent interferences, such as color-word inversion/latency, were obtained by stimulating precise white matter sites below the inferior and middle frontal gyri, anterior to the insula and over the putamen, and these were used to establish the posterior functional limit of the resection. Procedures implemented with iST dramatically reduced the EF deficits at 3 months. The EOR was similar in Stroop and control groups.

CONCLUSIONS: Brain mapping with the iST allows identification and preservation of the frontal lobe structures involved in inhibition of automatic responses, reducing the incidence of postoperative EF deficits and enhancing the further posterior and inferior margin of tumor resection.