What is an acoustic neuroma?
An acoustic neuroma, also known as a vestibular schwannoma or a neurilemmoma, is a benign, slow-growing tumor that develops on the nerves leading to the ear, which are responsible for hearing and balance.
In some patients, the tumor will grow large enough to put pressure on the brain and impact vital brain functions.
An acoustic neuroma is a rare condition that affects 2,000 to 3,000 people annually in the United States. If left untreated, acoustic neuromas can cause severe neurological problems, brain damage or death.
Causes of acoustic neuromas
A small number (5 percent) of acoustic neuromas can be attributed to a rare genetic disorder called neurofibromatosis type 2. The cause of the remaining cases is unknown.
Risk factors for acoustic neuroma
There are a few factors that appear to increase the likelihood of developing acoustic neuromas including:
- Family history — if you had a parent who had/has neurofibromatosis type 2 (NF2), you are more likely to develop the condition.
- Age — most people develop acoustic neuromas between the ages of 30 and 50.
- Exposure to radiation — people exposed to radiation in the head are more likely to develop acoustic neuromas later in life.
Symptoms of acoustic neuromas
Patients with an early stage acoustic neuroma may not feel any symptoms of the condition. Because acoustic neuromas grow slowly, it may take years before symptoms become more pronounced. Initial symptoms of acoustic neuromas may include:
- Gradual loss of hearing in the affected ear
- Ringing in the ear that is affected
- Dizziness or loss of balance
- Numbness in the face
Diagnosis of acoustic neuroma
Acoustic neuromas are difficult to diagnose in early stages because their symptoms are similar to other conditions. If your doctor suspects you have an acoustic neuroma, he or she will perform a full physical exam and hearing test.
During a hearing test, a hearing specialist, called an audiologist, can determine if you have any hearing problems. He or she will present various sounds at varying levels and ask you to indicate when you hear something.
Imaging tests, such as an MRI (magnetic resonance imaging) or CT (computed tomography) scan, are commonly used to diagnose acoustic neuromas. An MRI can detect a tumor as small as 2 millimeters.
Treatment of acoustic neuromas
Your doctor will evaluate your case to determine if you are a candidate for surgery or radiation. Patients who have very small acoustic neuromas and are not experiencing symptoms may not need any immediate treatment. These patients will need to be monitored every six to 12 months to determine if the tumor is growing.
If monitoring is not an option for you, surgery or radiation therapy are effective treatments for acoustic neuromas.
A craniotomy surgery is recommended for patients with large tumors who are experiencing moderate to severe symptoms from the growing acoustic neuroma. The goal of surgery to treat an acoustic neuroma is to completely remove the tumor and preserve hearing and balance function if possible. During a craniotomy, part of the skull is removed from behind the ear so that the tumor can be accessed easier. In most cases, surgery can control the tumor. In cases where the entire tumor can’t be removed, radiation therapy may be needed to destroy the remaining abnormal cells.
Stereotactic radiosurgery is an effective acoustic neuroma treatment for patients who have tumors less than three centimeters in diameter or for patients who are not candidates for surgery.
Gamma Knife is a type of stereotactic radiosurgery technology. Although the name of the technology indicates the use of surgery or knifes, it is actually the use of highly-targeted gamma ray beams directly to the affected area of the brain. The beam can destroy abnormal cells and have minimal effect on surrounding healthy tissue. Typically, one treatment, which can last from minutes to hours, is effective in treating the acoustic neuroma.