Preoperative functional magnetic resonance imaging in patients undergoing surgery for tumors around left (dominant) inferior frontal gyrus region

BACKGROUND: Preoperative functional magnetic resonance imaging (fMRI) helps to preserve neurological function and ensure maximal tumor tissue excision. We studied the lateralization and localization of speech centers in select cases of tumors around the left (dominant) inferior frontal gyrus (IFG). METHODS: Twenty-three right-handed patients, harboring tumors involving the left (dominant) IFG or causing mass effect or edema extending onto the left IFG, were recruited over 17 months. Preoperatively, all patients underwent language and speech assessment followed by MRI and fMRI with paradigm (picture naming). Normative data for language fMRI was taken from the institute's imaging data bank. RESULTS: The study included 23 patients [mean age: 38.9 (±11.9) years; M: F = 16:7; 9 – normal speech, 14 – abnormal speech]. Group analysis of controls showed significant activation in the region of interest (ROI) – left Brodmann's areas (BAs) 44,45. Group analysis of patients with normal speech showed no activation in the left BAs 44,45; however, activation was noted in the immediate adjacent areas, left BAs 13,47 and contralateral prefrontal cortex. Group analysis of patients with impaired speech showed no activation in BAs 44,45 or in the immediate adjacent areas. CONCLUSIONS: Neuroplasticity in the brain may enable functional language areas to shift to adjoining or distant regions in the brain when the primary areas are involved by intrinsic tumors. This phenomenon is more likely in slow-growing compared to fast-growing tumors. Preoperative language fMRI may help us in identifying and protecting these areas during surgery.