These tumors arise from the vestibular (balance) nerve, which is one branch of the vestibulocochlear nerve (8th cranial nerve). The other branch, the cochlear (auditory) nerve, carries sound signals to the brain. Early symptoms as the tumor grows and presses on the auditory nerve include slowly progressing hearing loss in one ear (hence the historical name acoustic neuroma).
(See also Overview of the Inner Ear.)
Early symptoms of acoustic neuroma include
Slowly progressing hearing loss in one ear
Noise or ringing in the ear (tinnitus)
Feeling of pressure or fullness in the ear
Imbalance or unsteadiness when the person turns quickly
If the tumor grows larger and compresses other parts of the brain, such as the facial nerve (7th cranial nerve) or the trigeminal nerve (5th cranial nerve), weakness (facial droop) or pain and numbness of the face may result.
Early diagnosis of acoustic neuroma is based on a magnetic resonance imaging (MRI) scan and hearing tests. An audiogram (hearing test) is done first. People who have hearing loss in only one ear should then have imaging tests, such as an MRI.
Tumors that are small and not growing or causing symptoms do not require treatment. Tumors that begin growing or cause symptoms are removed with surgery or controlled using radiation therapy. Surgery may be done using a microscope (microsurgery) to avoid damaging the facial nerve, and hearing can sometimes be saved. Radiation therapy may be done using a very precise technique (called stereotactic radiation therapy) so that only the tumor is affected. Whether surgery or stereotactic radiation therapy is done depends on a number of factors including the person's age, health, amount of hearing loss, and size of the tumor.