An acoustic neuroma is a benign tumor caused by the overproduction of Schwann cells that normally insulate the vestibulochoclear nerve, explains National Institute on Deafness and Other Communication Disorders. The cause of the overproduction is unknown, and the most common risk factor is exposure to radiation, notes WebMD.
About 5 percent of acoustic neuromas are associated with neurofibromatosis type 2, explains WebMD. Scientists believe that a mutation of a gene on chromosome 22 in patients with NF2 plays a role in the development of this tumor because the gene produces a protein that controls the growth of Schwann cells.
The initial symptoms of an acoustic neuroma include gradual hearing loss and fullness in the ear, according to WebMD. As the tumor grows and invades surrounding structures, it causes symptoms that include problems with balance, vertigo, intermittent facial numbness and tingling, facial weakness, taste changes, difficulty swallowing, hoarseness, headaches, clumsiness and confusion.
Treatment depends on the size of the tumor and includes observation, surgery and radiosurgery, describes NIDCD. Small tumors are usually removed with surgery because they are easier to isolate. Large tumors typically require treatment with radiosurgery because they invade the surrounding brain structures and are difficult to excise without extensive injury to other nerves.