Although the causes of brain meningioma are not completely clear, doctors know that radiation exposure and a genetic disorder called neurofibromatosis type 2 put individuals at risk for the tumors, according to WebMD. The hormone progesterone and head injuries may also be a factor. Although a study did not confirm injury as a cause of meningioma, the tumors develop near the sites of previous skull fractures or scarred membranes.
Meningiomas are the most common type of central nervous system tumor, explains WebMD. Ninety percent of them are noncancerous, but some can become cancerous later. Although they can form in the spinal cord, most meningiomas develop in the brain. They occur on the three layers of membranes that cover the brain and spinal cord, called the meninges.
The tumors usually grow very slowly, and some require no treatment. However, some tumors cause severe problems as they grow larger, and sometimes a meningioma can be fatal. Women are twice as likely as men to develop meningiomas, states WebMD. Most tumors develop in people between the ages of 30 and 70. Symptoms of meningioma include blurred vision, speech problems, headache and seizures. Some patients also experience numbness and weakness in the arms or legs.