Skull Base Meningiomas

Surgical excision is the treatment of choice for accessible skull base meningiomas. Nevertheless, a significant subset of complex tumors tightly attached to or encasing neurovascular structures cannot be removed safely. In such patients with residual or progressing disease after incomplete tumor resection, adjuvant external beam radiation therapy (RT) has been traditionally employed with a reported tumor local control up to 90% at 10 years. In the last decades, RT has evolved with the development of conformal and stereotactic techniques with dramatic technical advances in all aspects of treatment with better immobilization, imaging, planning, and treatment. Advanced radio-oncology techniques include intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT), and stereotactic radiotherapy (SRT) and radiosurgery (SRS) which allow for more precise dose delivery to the tumor while limiting the amount of radiation to the sensitive brain structures, i.e., the optic pathway and the brainstem. New radiation techniques, particularly SRS, have progressively emerged as an effective primary treatment of selected meningiomas of the skull base. Large series report local control rates of more than 90% at 5 years following SRS, which remain above 80% at 10–15 years. Although virtually noninvasive, SRS carries a risk of radiation-induced late toxicity, typically cranial nerve deficits causing impaired visual acuity and ocular motility. For patients with large skull base meningiomas or with tumors in close proximity to the optic pathway, fractionated SRS (2–5 fractions) has emerged as an alternative to single-fraction SRS with the hope of reducing the long-term consequences of treatment while maintaining its effectiveness. Currently, SRT and SRS are an essential part of the modern management of skull base meningiomas recurring after surgery or located at difficult accessibility.