What is the recommended management approach for a skull‑base meningioma, taking into account lesion size, exact location, symptom burden, patient age, and comorbidities?

Management of Skull Base Meningioma

Surgical resection remains the primary treatment for skull base meningiomas, but the goal should be maximal safe resection rather than radical excision, with adjuvant radiotherapy reserved for subtotal resections, atypical/malignant histology, or tumors with Ki-67 ≥5%. 1, 2, 3, 4

Initial Diagnostic Workup

Imaging Requirements:

• MRI with contrast is mandatory and should be performed within 2 weeks prior to any intervention, as it provides superior characterization of skull base anatomy, neurovascular involvement, and tumor extent 1, 2
• Look specifically for: homogeneous dural-based enhancement with "dural tail sign," degree of peritumoral edema, mass effect, relationship to cranial nerves and vascular structures (particularly carotid arteries and venous sinuses), and CSF cleft between tumor and brain 1, 2
• Consider preoperative angiography with possible embolization for extremely large tumors to minimize intraoperative blood loss, though weigh procedural risks carefully 5
• Somatostatin receptor PET imaging should be obtained when tumor extension is unclear or diagnosis is uncertain, as it has high accuracy in differentiating meningioma from other lesions 1, 2

Clinical Assessment:

• Document baseline neurological status including cranial nerve function (particularly CN II-VI for cavernous sinus/parasellar lesions, CN VII-VIII for cerebellopontine angle lesions), motor/sensory deficits, visual fields, and hearing 1, 6
• Assess for signs of increased intracranial pressure: headache pattern, vomiting, papilledema 1
• Evaluate for brainstem compression symptoms in posterior fossa/petroclival lesions 1
• Document seizure activity, which occurs in up to 30% of meningiomas 6

Treatment Decision Algorithm

For Symptomatic Skull Base Meningiomas:

Immediate Management:

• Initiate dexamethasone to reduce peritumoral edema in patients with neurological deficits 1, 6
• Start antiepileptic medication if seizures are present 1, 6
• Obtain immediate neurosurgical consultation for patients with significant neurological symptoms or brainstem compression 1

Surgical Planning:

• Multidisciplinary consultation is mandatory before surgery, involving neurosurgeons with skull base expertise, radiation oncologists, and potentially otolaryngologists for specific approaches 5, 3, 7
• The goal is maximal safe resection (Simpson grade I or II when feasible), NOT radical excision at all costs 2, 4, 7
• Skull base meningiomas require specialized surgical expertise due to deep location, involvement of critical neurovascular structures (cranial nerves, carotid arteries, venous sinuses), and technical complexity 5, 1, 8
• Image-guided neuronavigation is invaluable for operative planning 1

Expected Surgical Outcomes:

• Gross total resection (GTR) rates for skull base meningiomas range from 55.9-84.6% depending on location 3
• Cavernous sinus meningiomas achieve GTR in approximately 84.6% of cases 5
• Deep-seated skull base meningiomas carry 5-18% postoperative morbidity risk 2
• Brainstem meningiomas have significant early morbidity in nearly half of cases 2

For Asymptomatic Small Skull Base Meningiomas (<30mm):

Observation is appropriate when:

• Located in eloquent, deep, or brainstem areas where surgical risk outweighs benefit 2
• Patient has advanced age or significant comorbidities 2
• Surveillance protocol: MRI with contrast every 6-12 months 2

Surgery should be considered when:

• Tumor shows evidence of growth on serial imaging 2
• Tumor is accessible with acceptable surgical risk 2
• Patient is relatively young and healthy, as progression will inevitably necessitate treatment 9

Adjuvant Treatment Strategy

Radiotherapy Indications:

• WHO Grade III (malignant) meningiomas: External beam radiation therapy (EBRT) is indicated after surgery 2
• WHO Grade II (atypical) meningiomas with subtotal resection: EBRT should be administered 2
• Subtotal resection with Ki-67 ≥5%: Adjuvant radiotherapy is strongly recommended as Ki-67 ≥5% is an independent prognostic factor for recurrence 3
• Skull base meningiomas with extracranial extension: Subtotal/partial resection followed by radiotherapy is a reasonable strategy when radical resection is infeasible 3

Radiotherapy Techniques:

• Various radiation techniques (stereotactic radiosurgery, fractionated radiotherapy) have demonstrated efficacy for skull base meningiomas with high rates of local control and clinical improvement 4, 7
• Stereotactic radiosurgery may be considered for tumors in eloquent areas with unacceptable surgical risk 2
• The postradiotherapy MRI should be considered the "new baseline" for ongoing surveillance 2

Advanced Treatment Options:

• Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin receptor ligands shows promising results for treatment-refractory meningiomas 2
• SSTR PET imaging must be performed prior to PRRT to confirm target expression 2

Location-Specific Considerations

Common skull base locations include: clinoid processes, tuberculum sellae, dorsum sellae, sphenoid wing, petrous/petroclival area, falcotentorial region, cerebellopontine angle, and foramen magnum 8, 9

Cavernous Sinus Meningiomas:

• All cavernous sinus lesions in the literature were angioleiomyomas (ALMs), with GTR achieved in 84.6% 5
• 69.2% had no complications; 23% developed new postoperative cranial nerve deficits 5
• Require specialized skull base surgical expertise 5, 1

Petrous/Petroclival Meningiomas:

• Require specialized neurosurgical expertise for safe resection 5
• Higher risk of cranial nerve injury (particularly CN V-VIII) 8

Post-Treatment Surveillance

WHO Grade I (Benign) Meningiomas:

• MRI with contrast every 6-12 months 2
• Recurrence rates can be up to 20% within 25 years even after complete resection, necessitating long-term follow-up 2

WHO Grade II/III Meningiomas:

• More frequent surveillance imaging 2
• SSTR PET may be useful in distinguishing tumor recurrence from post-treatment changes 2

Critical Pitfalls to Avoid

• Do not pursue radical excision at all costs – the goal of radical excision should be abandoned despite microsurgical advances, as it leads to unacceptable morbidity 4
• Do not underestimate surgical complexity – skull base meningiomas require expertise in multiple skull base approaches with adequate bony removal, minimization of brain retraction, and respect for neurovascular structures 8
• Do not overlook the need for specialized surgical expertise – referral to specialized neurosurgical services with skull base experience is necessary for cavernous sinus, petrous bone, and other complex locations 5, 1
• Do not fail to recognize meningioma mimics – other entities such as brain metastases, gliomas, primary CNS lymphoma, hemangiopericytomas, and solitary fibrous tumors can mimic meningiomas 1, 9
• Do not underestimate blood loss risk – particularly with large tumors, preoperative embolization should be considered 5
• Do not delay adjuvant radiotherapy when indicated for subtotal resection with Ki-67 ≥5% or high-grade histology, as this is an independent prognostic factor 3

Special Population Considerations

Pediatric Skull Base Meningiomas:

• More likely to present with calcifications and cystic transformation 1
• Require specialized pediatric neurosurgical expertise 5, 1
• Referral to specialized neurosurgical services is recommended 5
• Blood loss has relatively bigger effect on smaller whole blood volume in children 5

Skull Base Meningiomas with Extracranial Extension:

• More common in males (50%) compared to typical intracranial meningiomas 3
• Higher histological grade (WHO II/III) than typical meningiomas 3
• GTR rate only 55.9%; median progression-free survival 54 months 3
• Multidisciplinary collaboration and individualized surgical strategies are crucial 3