This consultation is part of a series of consultations with Head and Neck Surgery specialists at the University of California, San Diego. In this hypothetical conversation between patient and doctor, we present an example case that is a composite of the most common signs and symptoms we see in patients who have this problem, along with the standard exams and treatments we recommend in a typical case. The discussion is no means exhaustive or comprehensive and the percentages used are only an approximation of those reported in the medical literature.
Whether or how a person is affected by a particular disease or problem can depend on the person’s age, gender, or race. In each consultation we present on the UCSD web site, we will indicate whether gender, age, or race makes a difference. The following consultation about acoustic neuroma could apply to any adult. The condition is most commonly found in men and women aged 30-60 years.
This consultation is presented for purposes of general information. If you think you have a similar condition, please see your doctor to discuss your individual case and the exams and treatments that are best for you.
An acoustic neuroma, also known as a vestibular schwannoma, is a benign (non-cancerous) tumor of the inner ear and intracranial cavity that grows along the course of the eighth cranial nerve, which is the nerve that controls hearing and balance. Most acoustic neuromas grow slowly, causing gradual or sudden loss of hearing in one ear, dizziness, and ringing (tinnitus) in the ear. Acoustic neuroma is one of the most common benign tumors of the brain, and is most often diagnosed in people between the ages of 30 and 60 years. Acoustic neuromas that grow large enough to cause symptoms are fairly rare, occurring in about 1 of every 100,000 people in the United States.
In our example, the patient is a 50-year-old man whose primary care doctor has referred him for evaluation of a progressive loss of hearing in his right ear.
Doctor: Good morning. How are you today?
Doctor: What brings you to see me?
Patient: I’ve developed a hearing loss in my right ear. My primary care physician ordered a hearing test and then sent me for an evaluation with a local ENT doctor. The ENT doctor looked at the hearing test, examined me, performed an MRI scan, and told me that I needed to come see you.
Doctor: Can you tell me when your hearing loss developed?
Patient: I think I’ve generally had a little bit of hearing loss as I got older, but then all of a sudden, over a period of 6 months, I noticed that the hearing in my right ear seemed to deteriorate. One day, I put the phone up to my ear, and I couldn’t hear anything out of my right ear. That’s when I went to go see my primary care physician.
Doctor: You only noticed the change in your right ear?
Doctor: Is there any ringing associated with it, in either your right or left ear?
Patient: Yes, I have fairly significant ringing in my right ear.
Doctor: Did you ever experience ringing before?
Doctor: Do you experience any vertigo, dizziness, or imbalances?
Patient: What’s vertigo?
Doctor: Vertigo is the feeling of spinning and that the environment is moving when it is not.
Patient: Sort of like when you go on a merry-go-round and get nauseated?
Doctor: Yes, that can be compared to it.
Patient: No, I’ve never experienced vertigo.
Doctor: Any imbalance or problems walking?
Patient: I did have a little off-balanced feeling for a few days about a year ago, but it went away in a couple of days. The doctor thought it might be high blood pressure.
Doctor: Is there any family history of non-cancerous growths in the inner ear or the covering of the brain? These might have been called acoustic neuromas or meningiomas.
Patient: Not that I am aware of.
The doctor then performs an examination and reviews the patient’s medical records.
Doctor: I see that your hearing test shows that you have a unilateral high-frequency sensorineural hearing loss in your right ear. Sometimes this kind of hearing loss is how a small benign tumor on the hearing nerve is first noticed. Your symptoms, with the hearing loss and ringing in one ear, are consistent with what we would see in a person who has one of these benign growths. The next step in diagnosing this type of tumor is to do an MRI, as your ENT doctor did.
Patient: Does my MRI show a tumor like that?
Doctor: Yes. Here on your MRI, we can see what is called a 1.2-cm enhancement of your eighth cranial nerve. That indicates a small growth, or tumor. Though it’s impossible to know exactly what this tumor is, your symptoms and what we see on the MRI scan suggest that it may be an acoustic neuroma, also known as a vestibular schwannoma.
Patient: But it is benign, and not cancer?
Doctor: This is most likely a benign tumor, not a malignancy or cancer. It grows from cells that surround your balance nerve, called Schwann cells. These tumors grow slowly, at a rate of 0-2 mm a year on average. They do not invade surrounding tissues, like a cancer does, and they do not metastasize or spread to other parts of your body.
Patient: Do I need some kind of treatment?
Doctor: There are three treatment options for an acoustic neuroma. When we select treatment for you, we consider your age and the hearing loss that you have already had. You’ve lost the hearing in the affected ear, and it is doubtful that it will come back. An acoustic neuroma can grow to a size that can cause other serious problems, possibly life-threatening problems. But a tumor like this grows so slowly – generally, less than a tenth of an inch a year -- that it can take a number of years before problems occur. And so the first option is observation, where we examine you once a year and watch to see if the tumor grows.
Patient: What are the other serious problems it could cause?
Doctor: The biggest concern is that, as the tumor continues to grow, it can compress the brain stem, as well as compress the other cranial nerves in and around your inner ear. These nerves control your balance and the movements of your face, sensation to your face, taste, swallowing, the movement of your tongue, your vocal cords, and the ability to shrug your shoulder.
Patient: So you’re saying that if I let the tumor grow, not only might I start to develop some dizziness, but I could get a paralyzed face?
Doctor: That is correct. And if the tumor were to compress the brain stem, or other structures in the brain, then there could be life-threatening problems. We would watch you closely by getting yearly MRI scans, and we would monitor the tumor very precisely to see how fast it is growing. If it is not growing at all, we would continue to do annual MRI scans. . If it is continuing to grow, we would go to one of the other two treatment options.
Patient: What are the other options?
Doctor: One option is to remove this tumor surgically. This will require a craniotomy, where we would actually enter your cranial cavity, which contains your brain, and perform the operation under the surgical microscope.
Patient: That’s beginning to sound like brain surgery.
Doctor: It is a brain surgery, and in fact we do this surgery as a team with the neurosurgeons here on staff. Most often, I work with Dr. John Alksne, who is a professor of neurosurgery also at UCSD. The surgery entails making a small hole in your skull behind your ear and, using a high-power surgical microscope, we identify the tumor in the internal auditory canal and remove it.
Patient: How long would I be in the hospital?
Doctor: The procedure requires an overnight stay in the intensive care unit (ICU), and a total of 3-5 days in the hospital, on average.
Patient: Does that surgery take care of the tumor permanently?
Doctor: With the surgery, the plan is to cure you of the tumor by removing it in its entirety. You would still need to have several evaluations and MRI scans to make sure that the tumor has not returned. In some cases, we leave a small amount of tumor on the facial nerve because it would cause paralysis if the very last bit were removed. In these situations, we do follow-up MRIs to determine whether the tumor is growing, but many times they do not grow.
Patient: Would the surgery bring my hearing back?
Doctor: Unfortunately, your hearing in the affected ear is gone, so the surgery will not restore it.
Patient: Are there risks and complications to the surgery?
Doctor: When we do this surgery, our major concern is the nerve that controls movement of your face. That nerve runs in the same canal as the nerve that controls hearing and balance. There is about a 10-20% risk that the nerve that controls movement of your face could temporarily become swollen, and this would result in either a partial or complete paralysis of your face. The majority of patients who have some degree of paralysis gain complete or near-complete return of function within a year. However, some patients -- especially those who have larger tumors -- do not regain full function of the muscles on that side of the face.
Patient: Is my tumor large?
Doctor: Yours is considered a small tumor because it is less than 1.5 cm in size.
Patient: Are there other risks?
Doctor: This surgery has the same risks as many other surgeries. There are risks associated with general anesthesia. There is a risk of bleeding, and a very small risk that you might have a stroke during the procedure. As I mentioned, there is the risk of damage to the nerve that controls function and movement in the face. There is also a risk of infection. The brain floats in a fluid called the cerebrospinal fluid, or CSF. After surgery, there is a small risk that the CSF can leak through the incision site, which creates an avenue for possible infection to the brain.
Patient: Is that like meningitis?
Doctor: Yes, that is meningitis. These complications are not common, but I have seen them before. Meningitis would be treated with antibiotics and would require an extended stay in the ICU. If you had a CSF leak, we would likely handle it conservatively by inserting a small catheter into the small of the back to reduce the spinal fluid pressure. The catheter is called a lumbar drain, and we leave it in place for 3 days. If that doesn’t work, we would open the incision and find exactly where the fluid is leaking and close it water tight.
Patient: What is the third treatment option?
Doctor: The third option is stereotactic radiosurgery-also known as Gammaknife, Cyberknife, or Trilogy. This is a technique using highly focused radiation to treat the tumor. There is no incision. You would receive a single treatment, which usually takes a total of a few hours in the facility, and you would then go home the same day.
Patient: So you’re saying that I can have an outpatient procedure that is over in a few hours versus an operation?
Patient: Why wouldn’t I choose the third option?
Doctor: It is entirely up to you. It is a very attractive alternative to open conventional surgery. The long-term results of the radiation are on par with the results from surgery, but the difference is that tumor is not gone. It undergoes changes from the radiation that are intended to make it stop growing. The risk of facial nerve paralysis and hearing loss from the stereotactic radiosurgery procedure is essentially the same as with surgery.
Patient: Are there disadvantages?
Doctor: Yes, there is a downside to stereotactic radiosurgery treatment. Occasionally the tumor begins to grow again. If the tumor does start growing at a later date, there would be more fibrous tissue and scarring in the area of the tumor because of the radiation. If we eventually had to remove the tumor surgically, the fibrous tissue and scarring would significantly increase the risk that your facial nerve would be damaged during the surgery.
Patient: So what are the general guidelines for when one has the surgery and for when one has the stereotactic radiosurgery treatment?
Doctor: In general, we consider the patient’s age and the tumor’s size. Usually, for patients who are approaching 60 years of age or greater and who may be in questionable health, either observation or stereotactic radiosurgery treatment would probably be a reasonable option. Observation is a good option for older patients, because the tumor may never get big enough to cause serious problems for the patient before the end of his or her life. The stereotactic radiosurgery procedure may, at the very least, inhibit growth of the tumor for at least 5 years. If the tumor starts to grow after that time period, we may be able to perform a repeat stereotactic radiosurgery treatment, or at that point, we can elect to monitor and track the tumor.
Patient: But I am 50, and my health is good overall.
Doctor: Yes. In healthier patients and patients who are under 60, the tumor will most likely start to cause problems if you just let it run its course without treatment. Surgery is a definitive way to remove the tumor in its entirety. Because your hearing is already gone, that eliminates one of the risks of surgery, which would be loss of hearing. There is also another reason to choose the open surgery for much younger patients. The long-term effects of radiation on benign tumors are not known. The stereotactic radiosurgery procedure may not be a wise choice in patients whose life expectancy is longer, because over time the radiation might result in a malignant transformation of the tumor or cause even another tumor to grow. The risk of this, of course, is small but there is a definite risk.
Patient: I think I understand the pros and cons of the treatment options. Considering everything, I think I would like to have the surgery. How do I arrange for that?
Doctor: Our nurse will coordinate that for you. Do you have any other questions?
Patient: Not at this time. Thank you, Doctor.
Doctor: You’re welcome.