Schwannomatosis is a rare form of neurofibromatosis that has only recently been identified. Affecting about 1 in 40,000 people, schwannomatosis causes the development of painful tumors – called schwannomas – usually on spinal and peripheral nerves. Because tumors do not develop on the nerve that carries sound and balance information from the inner ear to the brain (eighth cranial nerve), the condition does not cause deafness. Symptoms, which typically occur in adulthood, often include chronic pain due to tumors pressing on nerves as well as neurological features such as tingling or numbness.