Meningiomas are the most common type of primary brain tumor, representing about one-third of all brain tumors. These typically benign (non-cancerous) brain tumors develop from the meninges, the protective membranes that cover the brain and spinal cord. While most meningiomas grow slowly and are noncancerous, they can still exert pressure on the brain, nerves, or spinal cord and cause neurological problems.
Some meningiomas remain small and never cause any symptoms. They are frequently discovered on routine MRIs of the brain. They are often small, and a follow-up MRI will confirm that the meningioma is dormant. Others will grow and cause symptoms that require treatment. Evaluation by an experienced neurosurgeon is important to prevent complications and improve outcomes.
What Are Meningiomas?
Meningiomas originate from cells within the meninges, which is part of the protective covering of the brain and spinal cord. They can occur anywhere a part of the central nervous system comes into close contact with the skull or spinal column. Most meningiomas are WHO Grade I, which are benign, and if removed completely can be cured with surgery. Grade 2, atypical, tumors can be cured with surgery but have much higher rates of recurrence. Grade 3 meningiomas are malignant (cancerous). They require aggressive surgery, postoperative radiation and often chemotherapy. Fortunately grade 3 tumors are rare, but they are difficult to cure.
Meningiomas can occur in various parts of the brain, including:
- Convexity (top of the brain)
- Skull base
- Behind the eyes (olfactory groove)
- Along the spinal column
They are usually solitary, but some genetic conditions predispose patients to developing more than one meningioma. This can occur in neurofibromatosis type 2 (NF2).
Who Gets Meningiomas and When?
Meningiomas are most often diagnosed in:
- Adults aged 40–70
- Women, due to the fact that meningiomas frequently express sensitivity to progesterone and estrogen, the female hormones.
- African American populations
These tumors are rare in children but tend to be more aggressive when they occur.
Many meningiomas are discovered coincidentally during evaluations for unrelated issues, especially as MRI imaging has become common.