DEAR DOCTOR K:
I’ve been having trouble with my hearing. My doctor thinks it might be an acoustic neuroma and is ordering tests for that. I don’t like the sound of this. Isn’t an acoustic neuroma a type of brain tumor?
Yes, an acoustic neuroma is a type of brain tumor. There are really bad brain tumors and there are small, curable brain tumors. Fortunately, an acoustic neuroma usually falls into the small, curable category. Acoustic neuromas are benign (non-cancerous) growths, or tumors. Part of a nerve swells up into a little ball. These growths do not spread into other parts of the brain or body.
An acoustic neuroma grows on the cochleo-vestibular nerve (the eighth cranial nerve). This nerve allows a person to hear and is also connected to the balance center inside the ear. It carries sound and balance information from the ear to the brain. For that reason, the main symptoms of an acoustic neuroma are hearing loss and tinnitus (ringing in the ears).
Most people with acoustic neuromas have hearing loss when they have formal tests of their hearing. However, many of these people haven’t noticed the loss. A magnetic resonance imaging (MRI) scan can confirm the diagnosis. An MRI can show how big the tumor is and where it is located.
There is no way to tell how fast a tumor will grow except by checking periodically with an MRI scan. Some acoustic neuromas can grow quickly, but most grow slowly, taking years to become large enough to cause symptoms. And some acoustic neuromas do not grow at all after they are diagnosed.
So what should you do if you do have an acoustic neuroma? There are several options. The first is to do nothing: Just check to see if it is growing. Because of their typically slow growth, having a follow-up MRI and hearing test six and 12 months after diagnosis is a safe alternative to immediate intervention. If no changes are found, yearly checkups are considered adequate to monitor the tumor. If the tumor does not grow, and your symptoms don’t worsen, intervention is not needed. There is a small risk that further permanent hearing loss can occur during this “watchful waiting” period.
If the tumor is growing or is pressing on the brainstem, radiation or surgery will be necessary. The brainstem is responsible for many vital functions, including breathing and heart rate. It’s dangerous not to remove or shrink the tumor. Surgery will remove the tumor. But possible complications include loss of hearing and injury to the nerve that supplies motion to the face.
Radiation therapy does not remove the tumor, but it can stop the tumor from growing or cause it to shrink. Possible complications include loss of hearing, facial nerve injury and continued growth of the tumor.
It may seem strange or dangerous to do nothing about a type of brain tumor except to watch it. But this type of brain tumor often causes minimal problems. When that’s the case, doing something is a bad idea: The treatment can be worse than the disease.