These tumors arise from the vestibular (balance) nerve, which is one branch of the vestibulocochlear nerve (8th cranial nerve Overview of the Cranial Nerves Twelve pairs of nerves—the cranial nerves—lead directly from the brain to various parts of the head, neck, and trunk. Some of the cranial nerves are involved in the special senses (such as seeing... read more ). 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 Overview of the Inner Ear The fluid-filled inner ear (labyrinth) is a complex structure consisting of two major parts: The organ of hearing (cochlea) The organ of balance (vestibular system) The cochlea and the vestibular... read more .)
Early symptoms of vestibular schwannoma include
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 vestibular schwannoma is based on a magnetic resonance imaging (MRI) Magnetic Resonance Imaging (MRI) In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more scan and hearing tests Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss. More than 10% of people in the United States have some degree of hearing loss that affects their... read more . 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.
Other hearing tests that may be done include tympanometry Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss. More than 10% of people in the United States have some degree of hearing loss that affects their... read more (tests how well sound can pass through the eardrum and middle ear) and auditory brain stem response testing Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss. More than 10% of people in the United States have some degree of hearing loss that affects their... read more (measures nerve impulses in the brain stem resulting from sound signals in the ears).
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 Radiation Therapy for Cancer Radiation is a form of intense energy generated by a radioactive substance, such as cobalt, or by specialized equipment, such as an atomic particle (linear) accelerator. Radiation preferentially... read more . 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.