What is the preferred surgical approach for a skull‑base meningioma?

Skull Base Meningioma Surgical Approach

The surgical approach for skull base meningiomas must be tailored to the specific anatomical location, with pterional or orbitozygomatic approaches preferred for cavernous sinus lesions, endoscopic endonasal approaches for midline tuberculum sellae tumors, and retrosigmoid or combined petrosal approaches for cerebellopontine angle lesions—always prioritizing maximal safe resection over radical excision to preserve neurological function. 1

Pre-operative Planning Requirements

Multidisciplinary evaluation by skull-base-experienced neurosurgeons, radiation oncologists, and when appropriate otolaryngologists must occur before any surgical intervention. 1 This is particularly critical for pediatric patients, where joint procedures between pediatric neurosurgeons and skull base specialists are recommended for cavernous sinus, petrous bone, and cerebellopontine angle locations. 2

Essential Imaging

• Contrast-enhanced MRI must be obtained within 2 weeks before intervention to delineate tumor extent, neurovascular relationships, and peritumoral edema. 1
• Pre-operative digital subtraction angiography with possible embolization is recommended for very large skull-base meningiomas to reduce intra-operative blood loss, particularly in children where blood loss has disproportionate impact on smaller total blood volume. 2, 1
• Image-guided neuronavigation is strongly recommended for operative planning. 1

Location-Specific Surgical Approaches

Cavernous Sinus Meningiomas

• Pterional approach with or without orbitozygomatic osteotomy is the most frequently used approach for cavernous sinus lesions. 2
• Gross total resection is achievable in 84.6% of cavernous sinus cases, as these tumors typically arise from the interlayer between the lateral wall of the cavernous sinus and dura mater, allowing curative resection. 2
• Intraoperative electrophysiological monitoring of relevant cranial nerves is recommended. 2
• Expected morbidity: 23% develop new cranial nerve deficits, though 69.2% have no complications. 1

Tuberculum Sellae and Sellar Meningiomas

• Endoscopic endonasal approach is preferred for small, midline-placed tuberculum sellae meningiomas. 3, 4
• Endoscopic-assisted keyhole supraciliary mini-craniotomy offers low morbidity and good visual outcome, with 80% gross total removal rate. 4
• Mini-bifrontal basal and pterional craniotomies achieve better gross total removal for larger or laterally-placed lesions. 4
• The major limitation of the endonasal route is the narrow surgical corridor and restriction to midline-placed lesions. 4

Cerebellopontine Angle Meningiomas

• Retrosigmoid approach is common for cerebellopontine angle lesions. 5
• Intraoperative electrophysiological monitoring of cranial nerves is mandatory, particularly for facial nerve monitoring. 2

Medial Sphenoid Ridge

• This is the most frequent skull base meningioma location (29.6% of cases). 6
• Standard pterional approach is typically employed. 5

Petrous/Petroclival Region

• Combined petrosal approaches may be required depending on tumor extent. 5
• These locations require specialized skull base surgical expertise. 2

Surgical Goals and Extent of Resection

The operative goal is maximal safe resection (Simpson I-II when feasible); radical excision at any cost should be avoided. 1 This principle is critical because:

• Complete resection with dural attachment removal provides best tumor control but must not compromise neurovascular structures. 2, 7
• Overall complete resection is achieved in 62.8% of skull base meningiomas, with rates significantly correlated to tumor location. 6
• Some tumors are too difficult or dangerous to remove due to involvement of vital neural structures or encasement of major vessels like the carotid artery or venous sinuses—in these cases, subtotal resection followed by radiosurgery is the preferred strategy. 2, 8

Intraoperative Considerations

Blood Loss Management

• Excessive blood loss is a major concern, particularly in children where it has disproportionate impact on smaller total blood volume. 2
• Pre-operative embolization should be strongly considered for extremely large hemispheric tumors. 2

Neurovascular Preservation

• Careful evaluation of neurovascular structures surrounding the tumor is imperative to select the appropriate surgical corridor for safe resection. 3
• Tumors enveloping the carotid artery or venous sinuses may require subtotal resection. 2
• Intracavernous meningiomas exemplify lesions where multidisciplinary discussion regarding risks of surgical death or significant neurological deficits versus alternative therapies is particularly valuable. 2

Expected Outcomes

Neurological Improvement

• 60.1% of patients with focal neurological deficits experience significant improvement after surgery. 6
• Both neurological severity scores and performance status significantly improve from preoperative status to discharge, though improvement rates depend on tumor location. 6
• Visual acuity improves in 86.2% after transcranial approaches and 80% after transsphenoidal surgery for tuberculum sellae meningiomas. 4

Morbidity and Mortality

• Overall morbidity rate is 32.1% and mortality rate is 2.7%. 6
• New permanent neurological deficits occur in only 3.5% of patients. 6
• Deep-seated skull base meningiomas carry 5-18% postoperative morbidity. 1
• Brainstem meningiomas have significant early morbidity in approximately 50% of cases. 1

Adjuvant Treatment Strategy

For tumors where complete resection carries unacceptable risk, a staged approach combining initial debulking without attempting resection involving cranial nerves or basal vessels, followed by radiosurgery for small remaining tumor volume, results in reduced morbidity with long-term tumor control. 8

• Stereotactic radiosurgery provides tumor growth control greater than 90% with less than 10% incidence of new cranial nerve deficits. 8
• External beam radiotherapy is indicated for WHO grade III meningiomas after surgery and for subtotally resected WHO grade II meningiomas. 1, 7

Critical Pitfalls to Avoid

• Do not attempt radical excision at any cost—prioritize functional preservation over complete resection. 1
• Do not underestimate intra-operative blood loss risk—consider pre-operative embolization for large lesions. 1
• Do not overlook the necessity of referral to a skull-base-specialized neurosurgical team for complex locations such as cavernous sinus, petrous bone, and cerebellopontine angle. 2, 1
• Do not rely on a single surgical approach—dual-trained surgeons in both endoscopic and transcranial approaches achieve the best patient outcomes. 3

Surveillance Requirements

• Recurrence rate is 15.5% overall, with tumor size, bone and venous sinus infiltration, WHO grade, and poor extent of resection being independent predictive factors. 6
• Even completely resected benign meningiomas can recur in up to 20% of cases within 25 years, necessitating lifelong follow-up. 2, 1
• Contrast-enhanced MRI every 6-12 months is recommended for WHO Grade I meningiomas. 1, 7