Staged intervention to enable the resection of a large left temporoinsular cystic glioblastoma with language preservation: illustrative case.

backgroundResection of glioblastoma (GBM) in eloquent regions depends on functional mapping to limit perioperative neurological morbidity. When neurological deficits preclude reliable mapping, neurosurgeons should explore potential mitigation strategies. The authors present the case of a patient with a large left cystic temporoinsular GBM and aphasia, for whom the authors used intraoperative language mapping and a staged approach to enable safe tumor resection. OBSERVATIONS: A 49-year-old female presented with progressive mixed aphasia for 1 month and new-onset right facial droop. Magnetic resonance imaging (MRI) revealed a large, heterogeneously enhancing, left temporoinsular tumor with a significant cystic component. Her aphasia was profound, and resection without reliable language mapping was deemed unsafe. An initial stereotactic tumoral cyst aspiration was performed, which reduced local mass effect and improved her language function. Cyst decompression thereby enabled both task-based functional MRI and intraoperative awake speech mapping, resulting in a safe resection of her GBM. LESSONS: Safe resection of eloquently localized GBM is compromised when neurological deficits prohibit intraoperative functional mapping. This case demonstrates a mitigation strategy specific to cystic lesions in which an initial-stage stereotactic cyst aspiration is aimed at generating sufficient interval neurological improvement, such that intraoperative functional mapping can be performed during a second-stage resection. https://thejns.org/doi/10.3171/CASE24362.