NON-OPERATIVE TREATMENT WATCH & WAIT / WATCH & SCAN
If a patient chooses the observation / watch and wait option (generally reserved for smaller tumors), periodic imaging is required. Following initial diagnosis, a reasonable plan would be to get a new MRI scan in six months. If there is no growth, the next scan can be done one year later and then on an annual basis. If there are any new symptoms, your physician should be notified immediately. These changes could indicate that the tumor is growing more rapidly. By waiting, there is a risk you could lose part or all of your hearing in the involved ear.
There are two significant potential pitfalls with observation. First, it is critical that patients are absolutely prepared to insure that they will follow-through with MRIs as planned. Second, it is necessary to review all MRIs over time, rather than comparing any new MRI only to the immediately preceding one. Tumors may grow slowly enough so that no significant change can be seen over the course of one 6 or 12 month period even though there is significant growth over years.
If significant growth does occur during the observation period, active treatment is indicated and you and your physician may decide to choose between one of two therapies: radiation treatment or microsurgical resection.
RADIATION TREATMENT FOR ACOUSTIC NEUROMA
Radiation treatment for acoustic neuromas is typically done using one of several methods via which radiation is focused on the actual tumor. That is, a computer system is used together with MRI data to create a treatment plan by which the tumor receives a high dose of radiation, while surrounding structures receive a low dose. This is referred to as a “stereotactic” technique. Stereotactic radiation therapy, may be referred to as either "stereotactic radiosurgery” or "fractionated stereotactic radiotherapy" depending upon whether the treatment is done in a single session or is broken up over several sessions. This non¬invasive procedure can usually be performed on an outpatient basis.
There are several different ways to deliver the type of focused radiation required for effective treatment of an acoustic neuroma. Gamma Knife, LINAC, Novalis, XKnife, CyberKnife are all names of specific machines that deliver radiation. In each case, the beam that radiates the tumor consists of highly charged photons (x-rays or gamma rays); the differences lie in the way they produce the photons as well as the technology they use to focus the beam(s) to the specific area of the tumor. Proton Beam is a form of radiation treatment that uses a different principle to focus the radiation energy. You should discuss the various options for radiation treatment with your physician.
The goal of radiation treatment for acoustic neuroma is to stop or control tumor growth. The tumor is not removed or eradicated. Radiation is usually used to treat small and medium-sized acoustic neuromas (<2.5 - 3 cm). Radiation works by damaging the DNA inside cells and making them unable to divide and reproduce and by reducing blood supply or nutrients to the tumor. The dose of radiation used is chosen in order to maximize the effectiveness of treatment (chance of tumor control), while minimizing the risk to surrounding structures. In that the nerves involved with the tumor are immediately adjacent, they do receive a dose that is significant but low enough so as to have acceptable risk.
Tumors may continue to grow or swell for a period after treatment. Success of the treatment is eventually determined by the stabilization of tumor growth and in many cases the tumor then shrinks.
QUESTIONS FOR THE RADIATION TREATING MEDICAL PROFESSIONALS
If you have opted for radiation treatment of your tumor, you may want to ask some of the following questions of your radiation therapist, neurosurgeon, or neurotologist. Be sure that you are comfortable with the responses:
MICROSURGERY FOR ACOUSTIC NEUROMA
Surgery for acoustic neuromas is typically done using an operative microscope, or, occasionally, with the assistance of an endoscope. Decades ago, surgery for acoustic neuroma carried very high risks, including a significant risk of death. While the risks of major complications cannot be eliminated entirely, these risks are now extremely low in the hands of experienced surgical teams using modern equipment and techniques.
After safety, the primary goal of microsurgery is the preservation of function. The highest risks are to the nerves that are inherently involved with the tumor; that is, the facial nerve and the hearing and balance nerve. Both because facial nerve problems are usually considered to be more incapacitating than unilateral hearing loss and because satisfactory hearing results may be very difficult to obtain, facial nerve function is generally prioritized over hearing outcome. Hearing preservation is not always a realistic expectation, especially in cases of larger tumors. While many patients are very dizzy after acoustic neuroma surgery due to the fact that tumors are inherently part of the balance nerve, nearly all patients are able to compensate significantly (and often completely), for the physiologic loss of vestibular nerve function.
Three surgical approaches, translabyrinthine, retrosigmoid, or middle fossa, may be used for resecting acoustic neuromas. The choice of which procedure depends upon tumor size and configuration, hearing status, surgeons’ comfort level and patient choice. Not all surgeons are comfortable with each approach.
Over the past few years, attention has turned to the option of partial tumor resection. This is due to the availability of MRI for follow-up and to the presence of stereotactic radiation as a treatment option for the residual tumor. Generally, partial resection has the greatest role in the treatment of larger tumors, since total resection of these tumors may result in high rates of facial nerve injury and other problems. It should be clear however, that one surgeon’s definition of partial (or subtotal) resection may be quite different than another’s. It may be very difficult to estimate the amount of tumor left intraoperatively and a truly accurate assessment can only be made by follow-up MRI.
|NOTE: It's all right to get more than one opinion. Since acoustic neuromas are benign and slow growing (usually developing over several years), surgery should not be considered an emergency in most cases. Be cautious of anyone who tries to convince you to rush into surgery before you have taken the time to make an informed decision.
QUESTIONS FOR THE ACOUSTIC NEUROMA SURGEON
If you have decided to have your acoustic neuroma surgically removed, you may wish to ask some of the following questions of your surgeons. Be sure that you are comfortable with the responses: