Title : When left is right: Right-hemisphere language dominance enabling safe resection of a left-frontal glioblastoma in a right-handed patient
Abstract:
Background: Language is left-hemisphere dominant in approximately 90–95% of right-handed individuals (1–3). As a result, it is often assumed that left-frontal gliomas in right-handed patients involve critical language areas and are therefore not safe for surgical resection. However, maximal safe resection has been consistently associated with improved survival in glioblastoma and diffuse adult-type gliomas (4–8). Preoperative functional mapping techniques, including task-based functional MRI and Wada testing, can identify individual language lateralization and guide surgical planning (9–12). We describe a case in which presumed left-hemisphere language dominance did not hold, and formal assessment of hemispheric language dominance directly guided surgical planning and enabled safe tumor resection.
Case Presentation: A 68-year-old right-handed woman with limited English proficiency presented with transient right facial droop and subtle cognitive slowing. MRI of the brain revealed a 3.5-cm peripherally enhancing, centrally necrotic left-frontal subcortical mass. Biopsy confirmed glioblastoma, IDH-wildtype, CNS WHO grade 4. Preoperative imaging showed medial basal ganglia invasion and extension into the left insula and frontal operculum, suggesting tissue involvement of the regions critical for motor control, speech articulation, and expressive language, initially rendering extensive resection unsafe.
Intervention: Wada testing showed preserved language after left-hemispheric propofol injection but profound aphasia after right-hemispheric injection, confirming right-hemisphere language dominance (12). Memory was intact bilaterally. The patient was therefore deemed safe to undergo extensive surgical resection. She underwent left frontotemporal craniotomy for resection of brain tumor with brain motor mapping and 5-ALA fluorescence guidance. Intraoperatively, deeper dissection revealed tumor extension toward the lateral ventricle and proximity to the Sylvian fissure and insula adjacent to the corticospinal tract. Circumferential tumor resection was performed while preserving critical pathways. Near-total resection was achieved, leaving a minimal rim along eloquent white matter.
Outcomes: Postoperatively, the patient retained full motor strength, had no language deficits, and maintained baseline cognition. She started adjuvant therapy with temozolomide and concurrent radiation therapy four weeks post-operatively.
Conclusion: Right-hemisphere language dominance in a right-handed patient allowed safe maximal resection of a left frontal glioblastoma. This case highlights the importance of individualized presurgical language mapping to expand surgical options and optimize outcomes in glioblastoma patients (5, 9, 13). Language discordance may further contribute to disparities, as limited English proficiency can affect nuanced discussions about functional risk and influence access to advanced presurgical evaluation.
