Neurotologist Moises Arriaga and Neurosurgeon Frank Culicchia are members of the Acoustic Neuroma Association. Dr. Arriaga is a past president of the organization. CNC Hearing and Balance Center is recognized as an Acoustic Neuroma Center of Excellence.
Below is a transcript of Dr. Arriaga explaining treatment options.
Acoustic tumors are an important condition that can affect the hearing and balance nerve. These are benign growths of the lining of the hearing and balance nerve and they often start very small but they can grow to be quite large and even be life-threatening. Because they start very small and could present with just a little difference in the hearing, we are very aggressive at identifying them when they are small. So if there’s a difference in hearing between the two ears, we often will get an MRI to identify these growths. These are not cancers. They don’t go to other parts of the body but if they get large enough, they can put pressure on the brain and become life-threatening.
In general, there are 3 treatments for acoustic tumors.
For some patients, particularly if the tumor is small we will simply get another scan in 6 months and if it’s not growing, we will go ahead and scan on a yearly basis to make sure the tumor does not pose a threat.
Another treatment strategy is to remove the tumor and there are two ways to do that. In one strategy, we go right through the inner ear itself to reach the tumor. We cannot save the hearing but it means we don’t have to put any pressure around the brain to take the tumor.
The other strategy is one that gives us about a 70% chance of saving hearing and 50% chance of keeping the hearing at the current level. Those are hearing preservation tumor surgeries. We can do that from above with the middle fossa operation and from behind with the retrosigmoid operation.
The third general treatment for acoustic tumors is radiation. We like to use stereotactic radiation, which means the radiation is focused on where the tumor comes from. This is not like the old days where people get their whole head radiated and lose all their hair and have all sorts of brain issues related to that. Instead, this is highly focused radiation on the tumor. 90% of the time this radiation is effective at preventing the tumor from growing. However, whenever we use radiation we always mention the tiny possible risk of turning this from noncancerous to cancerous. Also, radiation is not very effective at preserving the hearing on a long-term basis. However, if the risks of surgery are substantial because of other medical problems radiation is a wonderful way to control these tumors before they get a chance to cause significant compression of the brain.
Retrosigmoid approach to acoustic tumor removal
The retrosigmoid approach is a workhorse approach for reaching tumors of the base of the skull and an area called the cerebellopontine angle. We often use it in acoustic tumors where we have an opportunity to try to save the hearing. In this operation, we actually make a cut way behind the ear so we don’t have to actually go through the inner ear, but we stay behind the main vein of the head on that side. That’s called the sigmoid sinus, and that’s why we call it the retrosigmoid approach. By staying behind that vein, we protect the inner ear, but have access to the area of the brain called the cerebellopontine angle. With the retrosigmoid approach for acoustic tumors, we have about a 50% chance of saving hearing at the preoperative level. If the preoperative testing tells us that the hearing nerve is still robust.
Translabyrinthine Approach to Acoustic Tumor Removal
When acoustic tumors involve the hearing and balance nerve or involve the brain next to where the hearing and balance nerve leaves the base of the skull, the translabyrinthine approach is a very useful way of safely removing the tumor and protecting the brain. In this operation, we make a cut behind the ear and then actually go through this bone called the mastoid bone, and carefully remove the inner ear to allow us access to the nerves that come from the brain, including the hearing and balance and face nerve, as well as to this whole area of the brain without having to put pressure on the brain. Because removing this bone opens up a huge window for the neurosurgeon to be able to access these areas as we work together to remove acoustic tumors that involve the base of the skull. In this fashion, we are able to have two places where we see the nerve of the face.
We see it as it’s entering the inner ear, and we see it as it’s just leaving the brain, entering the tumor itself. The translabyrinthine approach is a tried and true skull-based strategy for accessing acoustic tumors. It allows us to access small tumors just involving the internal auditory canal or large tumors that have caused significant destruction, but by using bone to reach the tumor, we, therefore, avoid compressing the brain. We are in an advantageous position of identifying the facial nerve, and we’ve got very good techniques for limiting complications like leakage of spinal fluid and problems resulting from pressure.