What it is
Meningiomas arise from the meninges — the layers of tissue that cover the brain and spinal cord — rather than from brain tissue itself. The majority are WHO grade 1, meaning benign and slow-growing. A smaller subset are grade 2 (atypical) or grade 3 (malignant), which behave more aggressively and require closer follow-up after treatment.
Because meningiomas grow slowly and originate outside the brain, many cause no symptoms for years and are discovered incidentally on imaging done for other reasons.
When treatment is needed
Not every meningioma requires intervention. Small, asymptomatic meningiomas in patients without high-risk features can often be safely observed with annual or biannual MRI. Treatment becomes appropriate when:
- The tumor is causing symptoms — seizures, focal deficits, headaches attributable to the tumor
- There is evidence of significant or accelerating growth
- The tumor is in a location where continued growth poses risk to critical structures
- The patient is young and the expected growth trajectory over decades favors treatment now
Surgical and radiosurgical options
For tumors amenable to resection — particularly those over the convexity of the brain or with favorable anatomy — surgery often achieves a cure. Complete removal (Simpson grade I or II resection) substantially reduces recurrence risk.
Stereotactic radiosurgery is well-suited for tumors that are small to medium-sized, in locations that make surgery high-risk, or that have regrown after previous surgery. It does not remove the tumor but arrests growth reliably in a large majority of cases.
The choice between observation, surgery, and radiosurgery is made after careful review of imaging, symptoms, patient health, and goals — not by a formula.