One type of tumor that can affect hearing is an acoustic neuroma. This is a slow growing, non-cancerous tumor that grows on the nerve connecting the ear to the brain. It’s located just behind the ear, and is not in the brain itself but is under it.
Because this type of tumor is benign, by itself it isn’t life threatening. It doesn’t metastasize (spread to other parts of the body) or turn into a brain tumor. It can, however, damage several important nerves as it gets larger.
Causes and Risks
Nobody has uncovered a “smoking gun” that causes acoustic neuromas. However, there’s evidence that a defective gene involved. This gene’s purpose is to prevent tumors from forming, and when it doesn’t work properly, an acoustic neuroma may be one result. Since acoustic neuromas are rarely dangerous and relatively rare, however, there’s not a lot of work being done to track down the cause or see if there’s a way to identify who’s really at risk.
Because these tumors are so small and slow growing, they generally don’t start causing symptoms until the patient is around 30 years old or so. Even then, the symptoms can be different from patient to patient.
Common symptoms may include vertigo or dizziness, hearing loss in the ear on the side where the tumor is located, and tinnitus in that same ear. Less often patients have a hard time understanding what people are saying to them, or have headaches in a particular pattern such as when then first wake up, or when they lie in a particular position for too long. They may lose their balance, have pain in the affected ear, be sleepy, or even have vision problems.
An acoustic neuroma can be hard to diagnose, because it often doesn’t show up on a regular physical exam. The test most often used is an MRI, but your doctor also may order a CT scan, a hearing test, or a brainstem auditory evoked response test (which tests hearing and brainstem function).
Once you know for certain that you have an acoustic neuroma, there are several possible paths you may choose to follow. Depending on where and how big the neuroma is, and how fast it’s growing, the first decision you need to make is whether to just watch it for a while or try to remove it. If it’s small and growing very slowly, the best course of action may be to just have periodic MRIs to watch it.
That said, however, some acoustic neuromas can damage the nerves that go from the ear to the brain, and the nerves that are associated with feeling and movement in the face. If the neuroma gets very large it may lead to an increase of fluid in the brain, which can be life threatening.
Although small neuromas often can be monitored, those that are large or fast growing, or are causing troublesome symptoms such as hearing loss, may need to be removed. One alternative to actual surgery is stereotactic radiosurgery. In this procedure, a high-powered x-ray is focused on the area of the tumor. This is not a surgical procedure, but is a type of radiation therapy. It’s an option that can slow down the growth of a neuroma that would be hard to remove with surgery because of its location or the overall condition of the patient.
There are risks involved with removing an acoustic neuroma. The surgery itself can damage nerves, which can cause hearing loss or loss of control of facial muscles. The surgeon can evaluate the risks based on where the neuroma is located.
If you have suffered hearing loss because of an acoustic neuroma and have the neuroma removed, your hearing will not come back. Once you’ve lost that hearing, it’s gone, but removing the neuroma should prevent any further hearing loss.