Surgical Resection of Small Interhemispheric Falx Meningiomas
For small (<30mm) asymptomatic interhemispheric falx meningiomas, observation is preferred over early resection, but surgery should be strongly considered if the tumor is easily accessible in a non-eloquent area or if there are potential neurological consequences. 1, 2
Treatment Algorithm Based on Size and Symptoms
Asymptomatic Small Meningiomas (<30mm)
- Observation is the preferred initial approach for asymptomatic small falcine meningiomas, particularly if located in eloquent areas or if the patient has significant comorbidities 1, 2
- Early surgical resection may be considered in select cases when the tumor is easily accessible in non-eloquent cortex, to prevent future hemorrhage, or if the patient requires anticoagulation for other medical conditions 2
- The median growth rate for meningiomas is only 4 mm per year, supporting a conservative approach for small asymptomatic lesions 1
Symptomatic Small Meningiomas (<30mm)
- Surgery is recommended if the tumor is accessible, followed by radiation therapy if WHO grade 3 or if incomplete resection occurs 1, 2, 3
- Symptoms warranting intervention include progressive neurological deficits, seizures, or disabling headaches 3
Why Not Resect All Small Meningiomas Early?
Surgical Risk Considerations
- The overall risk of death or nonfatal stroke after meningioma resection is approximately 6%, which exceeds the natural risk of a meningioma that has never bled (2.4% over 5 years) 1
- For falcine meningiomas specifically, surgical complexity is increased due to potential involvement of the superior sagittal sinus, risk of venous infarction, and proximity to eloquent motor cortex 3
- Permanent surgical morbidity ranges from 5-23% depending on tumor location, with deep-seated meningiomas carrying 5-18% postoperative morbidity 1, 2
Natural History Favors Observation
- Benign (WHO grade 1) meningiomas grow slowly at approximately 4 mm per year 1
- Many small asymptomatic meningiomas remain stable for years without causing symptoms 1, 2
- The risk-benefit calculation shifts only when symptoms develop or growth is documented on serial imaging 2
When Early Resection Is Justified
Surgery should be performed early (while small) in these specific scenarios:
- The tumor is causing seizures or progressive neurological symptoms 3
- The tumor is in a surgically favorable location (superficial, non-eloquent cortex) where complete resection with minimal morbidity is achievable 2, 4
- Serial imaging demonstrates clear growth, particularly if approaching critical structures 2
- The patient requires anticoagulation for other medical conditions, increasing hemorrhage risk 2
- Psychological burden is significant and the patient strongly desires definitive treatment 2
Optimal Surgical Timing When Intervention Is Needed
- Complete resection (Simpson grade I or II) is the goal when surgery is undertaken, as extent of resection directly correlates with recurrence rates 3, 5
- For falcine meningiomas, a "Grade Zero" resection (removing 2-3 cm margin of falx beyond tumor insertion) provides the best long-term outcomes, particularly for recurrent tumors 5
- Modern surgical techniques including image-guided surgery and virtual reality planning improve precision and reduce complications 2, 6
Critical Pitfalls to Avoid
- Do not delay surgical consultation once progressive disabling symptoms develop, as neurological deficits may become irreversible 3
- Do not underestimate the surgical complexity of parasagittal/falcine meningiomas due to venous anatomy—these require specialized neurosurgical expertise 3, 7
- Do not perform surgery solely based on size without considering symptoms, growth rate, location, and patient factors 1, 2