What is the recommended treatment for a diagnosed interhemispheric Falx meningioma?

Treatment of Interhemispheric Falx Meningioma (1.4 x 1.1 x 1.3 cm)

For a small (1.4 cm), asymptomatic interhemispheric falx meningioma, observation with serial MRI surveillance every 6-12 months is the recommended initial management approach, reserving surgical resection for cases demonstrating growth or development of neurological symptoms. 1

Initial Management Decision

Observation is appropriate for this tumor size given the following considerations:

• Small meningiomas (<30 mm) that are asymptomatic should be observed rather than immediately treated 1
• Your tumor at 1.4 cm falls well below the 3 cm threshold where intervention becomes more urgent 1
• The National Comprehensive Cancer Network specifically recommends observation for asymptomatic small meningiomas, with surgery reserved for accessible lesions where potential neurological consequences exist 1

Surveillance Protocol

MRI monitoring schedule:

• Obtain MRI without and with IV contrast every 6-12 months to assess for tumor growth 1, 2
• MRI is the gold standard imaging modality, providing detailed characterization of the lesion and surrounding structures 1, 2
• After achieving stable disease status (typically 5-10 years without growth), follow-up intervals can be extended 3

Indications for Surgical Intervention

Surgery should be pursued if any of the following develop:

• Neurological symptoms attributable to the tumor (headaches, seizures, motor weakness, sensory changes) 1, 4
• Evidence of tumor growth on serial imaging 1
• Development of significant mass effect or edema 2

Surgical Approach When Indicated

If surgery becomes necessary, the approach depends on tumor morphology:

• For hemispheroid-shaped tumors invaginating into one hemisphere (Type I): Use an ipsilateral interhemispheric approach 4, 5
• For olive-shaped tumors shifting the falx to the contralateral side (Type II): Use a contralateral transfalcine approach 4
• Complete resection (Simpson Grade I) including dural attachment is the optimal surgical goal when intervention is pursued 1, 3, 4
• Modern image-guided surgery (frameless stereotaxy) improves precision and reduces surgical complications 1, 3

Expected Surgical Outcomes

When surgery is performed for falcine meningiomas:

• Gross total resection is achievable in 85-87.5% of cases 4, 5
• Surgical mortality is essentially zero in modern series 4, 5
• Permanent neurological deficits occur in approximately 23% of cases 6
• Recurrence rates for completely resected benign meningiomas can reach 20% within 25 years, necessitating long-term follow-up 1

Alternative Treatment Options

If surgery becomes contraindicated or high-risk:

• Stereotactic radiosurgery (SRS) is effective for tumors <3 cm with 5-year progression-free survival rates of 86-99% 7, 3
• Fractionated stereotactic radiotherapy (SRT) may be preferred for tumors with pre-existing edema 7, 3
• Radiation therapy should be considered for eloquent locations with unacceptable surgical risk 1

Common Pitfalls to Avoid

Critical considerations:

• Do not assume all dural-based enhancing lesions are meningiomas - brain metastases, gliomas, and primary CNS lymphoma can mimic meningiomas 2
• Avoid premature surgical intervention for small asymptomatic tumors, as many remain stable for years 1
• Do not underestimate potential blood loss during surgery, particularly with larger tumors or those involving venous structures 3, 6
• Ensure preservation of bridging veins and anterior cerebral artery branches during any surgical approach 8, 6

Advanced Imaging Considerations

If diagnosis is uncertain or tumor behavior is atypical:

• Somatostatin receptor (SSTR) PET imaging provides superior detection sensitivity when tumor extension is unclear 7, 1
• SSTR PET is particularly useful for differentiating recurrence from post-treatment changes 7, 1