This type of brain tumor can harm hearing and balance. Here’s what to know about treatment options.
An acoustic neuroma, also known as a vestibular schwannoma, is a benign tumor that grows on the nerve connecting the inner ear to the brain.
Because of its location, this type of tumor can often cause hearing loss and other neurological problems, said Dr. Peter J. Morone, a neurosurgeon with the Vanderbilt Skull Base Center.
About 3,000 people per year in the U.S. are affected by an acoustic neuroma. And while the word “tumor” can be scary for patients to hear, it’s important to understand that vestibular schwannomas are mostly noncancerous and they grow slowly.
“These tumors arise from the nerve connected to the brain and only cause problems when they push on surrounding structures,” Morone said. “They usually do not spread within the brain or to other parts of the body.”
Types of acoustic neuromas
There are two kinds of acoustic neuromas. The majority are sporadic, meaning they occur spontaneously without any known cause. However, a less common type are associated with a syndrome called neurofibromatosis type II (NF2). That is a genetic (inherited) disorder involving the growth of noncancerous tumors in the nervous system. This is a rare cause of acoustic neuromas only about 3-5% of acoustic neuromas are caused by neurofibromatosis type II. However, this type often causes someone hearing loss in both ears before they are 30 years old.
“We don’t know what causes acoustic neuromas to develop,” said Dr. Kareem Tawfik, a surgeon with the Vanderbilt Skull Base Center. “We do know that the tumors are composed of Schwann cells, a special kind of cell that envelops nerves and helps transmit electrical impulses. In acoustic neuroma, the Schwann cells of the balance nerve, or vestibular nerve, become overactive and multiply unchecked. That’s why they’re also known as vestibular schwannomas.”
Symptoms and diagnosis
While some patients have no noticeable symptoms or problems, others complain of dizzy spells, vertigo, trouble hearing, facial numbness and sometimes weakness and problems with swallowing. Most acoustic neuromas are benign (meaning they’re not cancerous) and they stay within the internal auditory canal, a bony tunnel located deep in the base of the skull. However, some acoustic neuromas grow larger, and push on the brainstem, which can be life-threatening.
Acoustic neuroma symptoms and signs are often subtle and may take years to develop. Only when these tumors reach a very large size can they cause other problems, including difficulty with swallowing and blockage of the flow of cerebrospinal fluid.
“The most common symptom leading to diagnosis is hearing loss that’s worse in one ear, sometimes accompanied by ringing in the affected ear, or imbalance. It can also be an incidental imaging finding that’s picked up during evaluation of an unrelated problem,” Tawfik said. “There are many patients who have an acoustic neuroma but don’t experience any of the common symptoms.”
Treatment options
Treatment for acoustic neuroma depends on the size and growth of the tumor and your symptoms. If you have a small growth that isn’t causing problems, your doctor may simply monitor the growth with regular imaging and hearing tests. If the scans show the tumor is growing or if the tumor causes progressive symptoms, you may need treatment.
“If treatment is needed, we use a team-based approach to develop a personalized plan for each individual patient, taking into account a patient’s hearing status, tumor size and tumor location,” said Morone. “For some patients, radiation is the best option, while for others we recommend surgery.”
If surgery is recommended, multiple options exist, such as the “middle fossa approach” or a “retro-sigmoid craniotomy” (both of these procedures preserve hearing), and the translabyrynthine craniotomy, which does not. “When evaluating a patient for surgery,” Morone said, “we always consider completing a hearing-preservation approach if the patient has good hearing.”
When it comes to acoustic neuroma treatment, there’s no one-size-fits-all treatment plan, Tawfik said. Acoustic neuromas can be challenging to treat, so surgical removal should only be done by physicians with substantial clinical experience and expertise.
“Vanderbilt has a long history of being a center of excellence in the care of acoustic neuroma,” he said. “As one of the highest-volume acoustic neuroma programs in the country, we have a great depth of experience in all treatment modalities and hearing preservation techniques. It’s that type of nimble, multidisciplinary care that sets Vanderbilt apart.”
Expert tumor treatment
The Vanderbilt Skull Base Center customizes treatment for each patient’s needs, choosing the least invasive treatment for the best results possible. This team of doctors, nurses and other health care professionals are leaders in treating skull base tumors and related conditions. Vanderbilt Skull Base Center doctors have performed thousands of these surgeries. They have also helped train the next generation of doctors in this specialty.
