Meningioma

A meningioma is a tumor that grows from the meninges, the three layers of tissue that wrap around the brain and spinal cord. Picture them as three linings stacked on top of each other, covering the brain and spinal cord; the middle one is called the arachnoid. Meningioma is one of the most common primary tumors of the central nervous system, which simply means the brain and spinal cord. Primary means the tumor starts right there instead of spreading in from another organ.

Here's what happens inside. The arachnoid contains cells called meningothelial cells, and that's usually where the tumor begins. Meningioma cells usually carry one or more focal chromosomal deletions. Chromosomes are the strands where a cell stores its genetic information, and a focal deletion is a small piece of that strand that has gone missing. When other mutations pile on, meaning more changes to that information, they're linked to faster growth. And here's the key point: most meningiomas are benign and grow slowly.

What a meningioma causes depends on where it is and how big it is. Some people have no symptoms at all, while others have profound neurological deficits, which means a function controlled by the nervous system is seriously impaired. Headaches or seizures can also happen.