Acoustic neuroma (also called vestibular schwannoma) is a benign (non-cancerous), slow-growing tumor of the 8th cranial nerve (also known as the acoustic or vestibulocochlear nerve) which is responsible for hearing.
Location
Acoustic neuromas are usually located in the angle between the cerebellum and the pons, in the back of the skull (the posterior fossa).
Symptoms
Common symptoms of acoustic neuroma include one-sided hearing loss and buzzing or ringing in the ear. Dizziness may also occur, although it is less common. If the tumor affects the facial nerve (the 7th cranial nerve), facial paralysis may occur. Other symptoms include difficulty swallowing, impaired eye movement, taste disturbances, and difficulty with balance and coordination.
Treatment
Acoustic neuroma can be treated with surgery, radiation therapy (commonly stereotactic radiosurgery), surveillance, or a combination of these. The treatment selected depends on the tumor’s size, location, and severity of symptoms.
Prognosis
Prognosis means a prediction of outcome. This information is usually based on information gathered from groups of people with the same disease. It is important to remember these statistics are not individualized.
The prognosis for patients with acoustic neuroma is usually very good. Once treated, the risk of recurrence is low, less than 5%.
Incidence
Acoustic neuromas account for about 8% of all primary brain tumors. They typically occur in middle-aged adults, and females are twice as likely as males to have this tumor.
Age Distribution
Most acoustic neuromas affect patients between the age of 30 and 60 but can be diagnosed later in life as well.
Risk Factors
There are no known environmental factors that are associated with acoustic neuroma. It is caused by mutations in genes of the Schwann cells, which are found along nerves like the 8th cranial nerve. Acoustic neuromas can also be caused by a genetic disorder known as Neurofibromatosis 2 (NF2) which occurs in only 5% of patients.
Molecular Profile
Molecular profiling is the detection of specific genes, proteins, or other molecules in a tumor. This information helps confirm tumor diagnosis, inform treatment options, and predict prognosis.
Many genetic abnormalities are associated with acoustic neuroma. This includes loss of one of the segments of one of the two pairs of a chromosome 22, NF2 gene mutations and recombinations (exchange of genetic material), or gain of chromosome segments 9q34 or 17q. Loss of segments of chromosome 22 appears to be the most frequent abnormality.
Additional Resources
Content last reviewed:
September 2022 by Mia E. Miller, MD and John S. Yu, MD
