Skull Base Surgery

Skull base surgery encompasses a family of highly specialized surgical techniques designed to access, remove, or debulk tumors, vascular lesions, or other pathological entities arising at the base of the skull — a region of exceptional anatomical complexity that lies at the interface between the brain, the major blood vessels, the cranial nerves, and the upper airway. The fundamental challenge of skull base surgery is gaining adequate access to deeply situated lesions without causing unacceptable damage to the critical structures that traverse or abut this region. Skull base surgery is not a single procedure but a collection of approaches that the surgeon selects based on the precise location and nature of the pathology.

Preparation for skull base surgery is thorough and multidisciplinary. High-resolution MRI and CT imaging form the core of surgical planning. Angiography (CT or formal catheter-based) is performed when vascular encasement or a vascular tumor is suspected.

Audiological assessment documents baseline hearing function. Ophthalmological evaluation, including formal visual field testing, is obtained for parasellar and anterior skull base lesions. A complete endocrine panel is sent for all sellar and parasellar lesions. Speech and swallowing evaluation may be arranged for posterior skull base tumors expected to affect lower cranial nerves.  Medications affecting hemostasis are paused in the pre-operative period.

Skull base surgery is performed under general anesthesia, with the patient positioned to optimize both anatomical access and the safe continuous operation of neurophysiological monitoring leads. Operating times vary widely, depending on tumor complexity. The surgeon selects from a range of established approaches. Endoscopic endonasal approaches — entirely through the nose — are used for midline tumors such as pituitary adenomas, craniopharyngiomas, and clival chordomas, avoiding any craniotomy. Open craniotomy approaches include the pterional and orbitozygomatic approaches (for anterior and middle skull base), the retrosigmoid and translabyrinthine approaches (for the posterior skull base and cerebellopontine angle), and the transpetrosal approaches (for petroclival lesions). Combined endoscopic-open approaches are increasingly used for complex tumors crossing multiple compartments.

Intraoperative neuronavigation — a real-time GPS-like imaging system — guides the surgeon and reduces the risk of inadvertently entering critical anatomical areas. Neurophysiological monitoring of facial nerve, auditory brainstem responses, and lower cranial nerve function provides immediate feedback if surgical manipulation is affecting these structures. Patients are monitored after surgery, with typical hospital stays of three to seven days for uncomplicated cases.

The risks of skull base surgery are procedure-specific and depend heavily on the tumor's anatomical relationship to critical structures, but broadly include:

• Cranial nerve injury — the most clinically important risk; may affect facial movement, hearing, vision, eye movement, speech, or swallowing, depending on which nerves are involved in or near the tumor.
• Cerebrospinal fluid (CSF) leak — occurring through the surgical corridor, usually manageable with additional packing, lumbar drain, or secondary repair.
• Infection — including meningitis or wound infection
• Vascular injury — potentially causing stroke; careful preoperative angiographic planning and intraoperative vigilance are critical.
• Incomplete resection — for many skull base tumors, total resection is not possible without unacceptable neurological risk, and planned subtotal resection followed by adjuvant radiation is the appropriate strategy.

Surgical outcomes are tumor-specific. For benign tumors such as grade 1 meningiomas, complete resection provides the best long-term tumor control, though recurrence remains possible over decades of follow-up and surveillance MRI is lifelong. For chordomas and chondrosarcomas, maximal surgical resection followed by high-dose proton beam or carbon ion radiation is the standard approach and achieves favorable long-term local control rates. Postoperative rehabilitation — addressing cranial nerve deficits through facial physiotherapy, swallowing therapy, and audiological management — is an essential component of comprehensive skull base tumor care.