Making Your Treatment Decision
Receiving a diagnosis of Acoustic Neuroma can be very alarming. Acoustic Neuromas are slow-growing, benign tumors, and it is quite possible that the tumor has been there for some time before it is discovered. Urgent treatment is rarely needed, so you will have time to think about how you would like to treat your acoustic neuroma.
Almost everyone has three choices for managing your acoustic neuroma: close observation (yearly MRI), surgery or radiation treatment. You might decide on a different path at a later date. Many patients at first choose to observe with a yearly MRI and later decide to have the tumor treated either because of tumor growth or a change in their hearing loss or other symptoms. In some cases we will recommend additional testing to give you more information on your options. The flowchart below shows our approach to your initial experience:
Three basic treatment approaches
Let's look at those three basic approaches to managing an Acoustic Neuroma more closely:
- Observation: On average, acoustic neuromas grow 1-2 millimeters per year. However, some tumors grow very slowly (or not at all). Rarely, tumors grow much faster. Because of this slow growth, observation with yearly MRI and hearing test is a reasonable choice for many patients. This may depend upon the size of the tumor, your age, general health, and preferences. This option is particularly good for small tumors in older patients. Because of the small possibility of rapid tumor growth, your first repeat MRI would be at 6 months. Your hearing will most likely continue to decline over time, whether or not we see growth of the tumor on MRI. It is important to remember that even if the tumor does not grow on the MRI, it may still be affecting your hearing. This is why the hearing test is also important.
- Stereotactic Radiation: This treatment involves radiation beams from multiple sources that are directed at the tumor. This keeps radiation away from tissue that surrounds the acoustic neuroma. In most cases, radiation is given in one dose in a single day. Occasionally, radiation is given over multiple days (“fractionated radiation treatment”). Radiation is very good for stopping Acoustic Neuroma growth and in some cases tumors may get smaller after radiation. But, the tumor is still there after radiation. Because radiation is most effective in stopping tumor growth, we generally recommend this option only after we see tumor growth on repeat MRI. Stereotactic radiation does not keep hearing in most cases; so it is possible that your hearing in that ear will get worse with time. The effects of radiation upon balance function are unpredictable. Finally, there is a very small (less than 1 in 1,000) chance of converting a benign tumor into a malignant process with radiation.
- Surgery: There are three surgical approaches to acoustic neuroma and all three approaches are performed at DHMC. We will consider multiple factors to carefully select a surgical approach best suited for your particular case. In general, we believe that the goal of surgery should be complete tumor removal. Complete resection gives the best chance of never having to have another treatment for your tumor. Recurrent tumor growth after adequate surgical resection is very rare. In very rare cases where the tumor is firmly attached to the facial nerve, a small fragment of tumor may be intentionally left behind.
Your tumor size and location, as well as your level of hearing, will determine which surgical approaches will be recommended. The first factor to be considered is whether or not your current hearing can be saved. The size of the tumor and how much hearing you have already lost help us to tell you whether your hearing may be preserved with surgery. If you have good hearing, it is more likely that your hearing can be saved. If you have already lost a lot of your hearing, then it is less likely that hearing can be saved. In most cases, surgery cannot restore hearing that is already lost. There are options to help with your hearing if you have already lost the hearing from the tumor or we are unable to preserve your hearing with surgery.
There is also a risk of injury to the facial nerve with surgery. This nerve supplies the muscles of your face allowing you to smile, close your eyes, etc. The risk of facial nerve paralysis is also directly related to the tumor size. For most small or medium size tumors this risk is low. Some patients will experience a temporary weakness of the facial muscles which then recovers. During surgery, we monitor your facial and hearing nerves to reduce risk of injury to these nerves.
Regardless of the approach, the effects of surgery on balance function are fairly predictable. Because the tumor arises from the balance (vestibular) nerve, this nerve is removed from one ear along with the tumor. You have another balance nerve in your opposite ear. Most people do not need both balance nerves, but your brain will have to learn to compensate for the lost balance of the balance function on one side. In many cases, the balance nerve with the tumor is already not working well, so removal causes minimal problems. Until your brain learns to compensate, you will have more dizziness in the days after surgery. The worst dizziness is the first few days after surgery, this gradual improves over the following few weeks.
A rough outline of our philosophy on selecting a surgical approach is shown in the figure below, but many individual factors may go into choosing a surgical approach that is best suited to your needs.
- Middle Fossa Approach: This is an approach above the ear that is used for small tumors and when we feel that you have enough hearing remaining that it may be saved.
- Retrosigmoid Approach: This surgical approach comes from behind the ear and is better suited for tumors that are located further back in the ear canal and when we believe that hearing may be preserved.
- Translabrynthine Approach: This surgical approach comes from above the ear canal and goes through the bone. Hearing cannot be preserved with this approach, but there may be less risk to the facial nerve. We do not monitor hearing during this surgery, since hearing preservation is not a goal with this approach.
Additional testing prior to surgery
In some cases, we will need to do additional testing to plan for your surgery and to decide which approach is best.
- VNG (vestibular nystagmography) shows balance function in your inner ear.
- ABR (auditory brainstem response) determines the hearing nerve function.
- We may get a CT scan of your hearing bones to plan for surgical approach.
- In some cases, an additional high resolution MRI (FIESTA MRI) is needed to better visualize your hearing and facial nerve anatomy and the tumor location.
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