An acoustic neuroma (vestibular shwannoma, eighth nerve tumor) is a slow-growing or non-growing benign tumor that forms on the vestibular nerve that leads from the inner ear to the brain.
It rarely causes problems with the facial nerve or vital bodily functions, however it can cause other issues. The size of the growth does not necessarily correspond with the severity of the condition. Even a small acoustic neuroma can produce symptoms. It is thought to be caused by a faulty gene on the 22nd chromosome or early exposure to low levels of radiation on the neck and/or head.
Patients who suffer from neurofibromatosis type 2 (NF2), a hereditary genetic disorder, are at special risk of being susceptible to vestibular schwannomas. About 5 percent of cases arise are related to NF2. Researchers believe that a gene on chromosome 22 mutates in patients with NF2. The mutation is significant because this chromosome produces a protein that controls the growth of Schwann cells.
Although NF2 is inherited, vestibular schwannomas cannot be inherited. Most tumors occur individually; only 5-10 percent of patients develop multiple schwannomas.
Some researchers believe that exposure to high doses of radiation, especially to the head and neck, contribute to the creation of too many Schwann cells, resulting in the tumors. For example, a patient who undergoes radiation therapy as a child or young person may contract acoustic neuromas later in life.
Other areas of research include studies of prolonged exposure to loud noises on the job (an environmental factor).
Although rare, an acoustic neuroma can grow to sizes that can result in complete hearing loss, dangerous build-up of spinal fluid and/or life-threatening brain stem compression.
Early diagnosis through an MRI and hearing exams can prevent further complications and enable the doctor to determine the best course of action. Acoustic neuromas may be regularly monitored if small. The doctor will decide whether or not it should be removed using microsurgery or stereostatic radiosurgery to avoid hearing and facial nerve damage.
Treatment options will depend on age, candidacy for surgical removal and the precise location and size of the tumor.
According to the Florida Hospital System, prevention of acoustic neuroma is not possible due to the nature of the condition.
Doctors suspect environmental factors may cause nerve damage that leads to acoustic neuroma, but support for those assumptions remains elusive.
Research into investigational therapies continues with a number of drug studies. One group of researchers found that aspirin was related to slowed tumor growth in patients. Aspirin may work because it inhibits the inflammatory chemical cyclooxygenase. Production of cylooxygenase has been associated with the rate of tumor growth in patients with acoustic neuroma.
In addition to aspirin, other drugs are being tested for treatment of acoustic neuroma, particularly in patients with NF2. Both private and public clinical trials continue.