An acoustic neuroma is a benign growth that originates in the nerves that carry balance signals from the inner ear to the brain. This nerve runs next to the acoustic nerve, which carries hearing signals, and the facial nerve, which carries the signals that move the muscles of the face.
Acoustic neuromas are most commonly diagnosed in people in their late-40s and early-50s. However, with the advent of more accurate scanning technology, they are being discovered at a smaller size and, therefore, at a younger age than just 20 years ago.
What causes Acoustic Neuroma?
There is no known cause of acoustic neuromas. The tumor itself often shows a genetic mutation, but it is usually not an inherited one. Rather Instead, the changed gene shows up only in that individual, affecting the growth of the nerve sheath.
A less common form, neurofibromatosis type 2 or “acoustic neurofibromatosis,” is inherited and associated with multiple tumors of nerve sheaths and of the membranes that line the skull. If a person has an acoustic neuroma on both sides of the head, or an acoustic neuroma and a meningioma, acoustic neurofibromatosis is a possible diagnosis.
How is Acoustic Neuroma diagnosed?
Frequently a patient’s first experience relating to an acoustic neuroma may be episodes of dizziness. Because those symptoms are usually brief, it is often suspected to be nothing more than an inner ear infection.
The next symptom is typically partial hearing loss. When hearing starts to decline, a person usually seeks additional medical help and requests further evaluation. A hearing test may reveal that the hearing loss occurs in one ear only, which is often a sign of acoustic neuroma. A follow-up MRI can determine whether a tumor is present.
What are the treatment options for Acoustic Neuroma?
While there are currently no medications that are effective in treating acoustic neuromas, there is a wide spectrum of treatments — with a wide spectrum of risks. Treatment ranges from watchful waiting, where the progression of the disease is carefully monitored, to surgical removal.
Success of the treatment depends on several factors:
• Watchful waiting is the treatment commonly chosen for a patient with a small tumor and good hearing.
• Watchful waiting is also frequently chosen for a person with a small tumor where hearing is poor, because there is little to gain from treatment.
• For patients with small tumors and good hearing, there is an opportunity to preserve the hearing with surgery to remove the tumor. This type of surgery is successful in 50 to 70 percent of cases, depending on the particular case.
• Surgical removal for a large tumor is necessary if the tumor is pushing on the brain, because it may cause secondary, life-threatening problems, such as buildup of spinal fluid.
Another way of treating acoustic neuromas is with stereotactic radiosurgery. In this procedure, radiation is directed at the tumor with pinpoint precision. The entire treatment is planned and delivered by computer to limit the radiation to the exact site of the tumor. Unlike traditional surgery, the tumor is not removed, yet the radiation has the potential to slow or stop the growth of the tumor.
Stereotactic radiosurgery may be an adequate treatment for a patient who is not experiencing problems related to the tumor but wishes some form of treatment or who will be satisfied if the tumor does not get much larger. It may also be the best choice for people who are on blood or have other health conditions that make surgery unusually dangerous.
What can be expected with a diagnosis of Acoustic Neuroma?
The average growth of acoustic neuromas is estimated to be about one to two millimeters in diameter per year. Because they are generally benign and slowly growing, the outlook for people with acoustic neuromas is usually very good.
If ignored and not treated in a young person, the tumor can eventually grow to such a size that becomes life threatening. In young people, tumor removal cures the patient in about 98 percent of the cases. The lifetime recurrence risk if the tumor is completely removed is about 1 to 2 percent. For the younger, healthier person, surgery is frequently appropriate, in order to eliminate
not only the problem but the worry as well.
King’s Daughters neurosurgeon Ondrej Choutka, M.D., is experienced in treatment of all types of brain tumors, including acoustic neuromas. For more information, please speak with your primary care physician or call his practice at (606) 329-1770.