Meningiomas are the most common benign brain tumors. Meningiomas account for 20% of all brain tumors and about 25% of all primary spinal cord tumors. The brain is protected by three layers of tissue called the meninges. The outer layer is composed of thick dura mater, where meningiomas begin growth. The middle layer is called the arachnoid and the innermost layer is known as the pia mater.
Meningiomas are more common in women than in men. While meningiomas affect people of all ages, they are most common among people in their forties. Meningiomas generally grow slowly, usually do not invade surrounding normal tissue and rarely spread to other parts of the central nervous system or body.
Gamma Knife is a primary method for the control of meningiomas. Radiosurgery can be the initial treatment for difficult to operate skull-based tumors or in the treatment of tumors recurring after open surgery. Skull-based meningiomas frequently recur after operation and conventional surgery may occasionally lead to increased cranial nerve dysfunction. Tumors arising from the cavernous sinus, and petroclival tumors of the posterior fossa are especially good candidates for Gamma Knife radiosurgery, as complications of complex, skull base surgery are avoided. Gamma Knife has a 95% control rate for the treatment of meningiomas.