Neurofibromatosis 2 is a disorder in which noncancerous tumors called schwannomas develop in cells that form the protective covering for nerves in the inner ear. Tumors can also develop on nerves in other areas of the brain or spinal cord. Neurofibromatosis 2 is a subtype of neurofibromatosis. Signs and symptoms usually appear during adolescence or in a person's early 20s. The most common early symptoms are hearing loss, ringing in the ears (tinnitus), and loss of balance, which are caused by schwannomas growing on the nerve leading from the ear to the brain. If tumors develop in other parts of the brain, signs and symptoms vary according to the tumor's location and can include seizures, changes in vision or sensation, and fluid buildup in the brain. Some people with neurofibromatosis 2 also develop cataracts (clouding of the lens in the eye) at an early age.