Skull Base Meningiomas with Extracranial Extension: Outcomes and Patterns of Failure after Radiosurgery in the Primary or Adjuvant Settings, and a Multidisciplinary Management Algorithm

Meningiomas are typically benign extra-axial tumors treated with surgery or radiosurgery, but extracranial extension from skull base lesions is rare and poorly defined. This study reports outcomes of stereotactic radiosurgery for skull base meningiomas with extracranial extension, focusing on tumor control, clinical outcomes, and patterns of failure. We conducted a retrospective single-institution review of patients treated with gamma knife radiosurgery (GKRS) for skull base meningiomas with extracranial extension. Clinical, radiographic, and treatment variables—including extension patterns, cranial nerve involvement, and dosimetry—were analyzed. Tumor control and symptom outcomes were assessed using univariate and multivariable analyses. Kaplan–Meier and Cox regression analyses compared primary versus salvage GKRS. A management algorithm was developed based on a literature review. Thirty-four patients were included: 13 treated with primary GKRS and 21 with salvage GKRS after prior treatment. The most common extracranial extension sites were the pterygopalatine fossa and orbit, and visual changes were the most frequent symptom. Symptomatic deterioration was associated with larger tumor volume, higher maximum dose, foraminal extension, female sex, and prior treatment. Hyperostosis, prior treatment, and higher histologic grade predicted retreatment. At the last follow-up, over 90% of patients achieved radiographic tumor control and symptom stability. Primary GKRS was associated with fewer complications and better tumor control than salvage treatment. GKRS provides durable tumor control and favorable clinical outcomes for selected skull base meningiomas with extracranial extension. When feasible, primary radiosurgery may be preferable to salvage therapy. Predominant intracranial marginal progression supports targeted surveillance and a multidisciplinary, risk-adapted management strategy.