Acoustic Neuroma Program

Acoustic neuroma and vestibular schwannoma are synonyms. They are benign (i.e., non-cancerous) tumors that are typically slow growing. They most commonly present with hearing loss, and that is why historically they were referred to as "acoustic" tumors. We now know that they actually arise from the insulating cells (Schwann cells) of the vestibular nerve, hence the more accurate term "vestibular schwannoma."

It is said that there are three treatment options for acoustic neuromas: observation (also called "wait and scan"), surgery, and radiation. Specific treatment recommendations are formulated on an individual basis, and depend on three important variables: tumor size, patient age, and hearing status.

We prefer not to treat tumors when they are first diagnosed since some of them will remain dormant for years (particularly those diagnosed incidentally) and there is little risk of tumors progressing rapidly. Ideally, we reserve treatment for tumors that are growing or symptomatic. That having been said, tumors sometimes present when very large and treatment in those cases is urgent or even emergent.

For patients who are ideal candidates for hearing preservation surgery (middle fossa craniotomy), good or useful hearing is preserved approximately two-thirds of the time (meaning AAO-HNS class A or B hearing). It is common for patients to experience a decrement of 10 to 15 dB in hearing after surgery so the better your hearing at the time of surgery, the better the odds of keeping excellent hearing after surgery. The best odds for removing the whole tumor and saving hearing is for small tumors, generally less than 15mm in maximum dimension. Other factors such as the surgical approach and tumor location can also influence the odds for hearing preservation.

Radiosurgery is, like wait and scan, not a hearing preservation treatment strategy.

Acoustic neuromas cause hearing loss over time. Hearing loss does not require growth of the tumor, and is at most very loosely correlated with tumor size. Interestingly, the reason these tumors cause hearing loss is not fully understood. Radiation treatment is not compatible with hearing preservation, though whether this is because radiation does not remove the tumor or because of the toxicity of treatment is also unknown.

Therefore, the best way to keep your natural hearing for the remainder of your life is with successful surgery for hearing preservation, assuming the tumor is small enough to be a candidate. Unfortunately, with surgery there is also a significant chance to lose hearing, so surgery is at the same time the best chance to save your natural hearing until old age and simultaneously the quickest way to lose hearing.

There is no risk to the unaffected ear, such that when deafness occurs, it is single-sided deafness only.

Generally speaking, hearing does not improve after surgery for tumor removal. In recent years the morbidity of single sided deafness has been better understood and this has led to an increased effort to rehabilitate hearing when lost, whether with a wearable hearing aid or an implanted device such as a cochlear implant or bone anchored hearing aid. At UCLA, we are committed to rehabilitating hearing for every patient, whether deafness occurred before or after treatment.

For benign tumors like acoustic neuroma a radiation technique called radiosurgery is preferred. Radiosurgery basically means the delivery of radiation with "surgical intent," i.e., to target the tumor itself and spare the surrounding tissue, as though with a scalpel. The goal of radiosurgery is called "tumor control" by which we mean that the tumor has ceased growth. The goal is not to kill the tumor or melt it away.

Radiosurgery was first introduced for the treatment of acoustic neuroma around 1990 with the Gamma Knife; initially the doses used caused a high risk of facial palsy and so over decades the dose has been refined to the minimal dose that can be given to achieve tumor control- about 12.5 Gy if delivered in a single session. There are many machines that are capable of performing radiosurgery, and sometimes the treatment may be spread over three to five days rather than a single session (called fractions). There are unfortunately very few high-quality studies that compare radiation treatment approaches head-to-head, but if you are being treated with radiation for acoustic neuroma, you should make sure that you are being treated with a radiosurgery treatment plan.

Irrespective of the platform used to deliver radiation, certain commonalities exist. First and foremost is that radiosurgery for acoustic neuroma is very different than radiation delivered for cancer — the dose prescribed is not a lethal dose, but rather a dose designed to change the behavior of the tumor (to prevent growth). If it were a high dose, the collateral damage radiation would do to the facial nerve and brainstem would make the treatment worse than the disease, and the risks of treatment much higher than with surgery. Because the surrounding brain tissue receives so much less radiation with radiosurgery than with conventional radiation, a lot of the side effects one associates with radiation (hair loss, fatigue, nausea, etc.), generally speaking, do not apply to radiosurgery. That having been said, because of the accuracy of radiosurgery and the steep drop-off of dose that these machines are able to achieve, the tumor receives a relatively large dose per fraction. This — relatively high dose to the tumor, low dose to neighboring brain — is the key to obtaining tumor control and minimizing complications.

Finally, following radiosurgery shrinkage of the tumor is not uncommon but is only seen ~40% of the time. Moreover, the effect of radiosurgery treatment is not immediate. It generally take a minimum of six months to halt growth and may take up to two years, so we generally are very reluctant to consider a radiation treatment to have failed before waiting this long. For this reason also, radiation may not be the treatment of choice for tumors that are causing a lot of symptoms by putting pressure on the brainstem or nerves.

Although it has been in use for decades, we still do not fully understand how or why radiation delivered in this way works!

The risks, or complications, of radiation treatment can be segregated into three distinct time periods. Early complications following radiation treatment occur in the days during or immediately following completion of treatment and are typically limited to headache, nausea, and are usually well controlled with short course of steroids. Intermediate complications occur usually within six months to two years after treatment, and include facial weakness in 1 to 2% of patients, numbness in 3 to 4%, and adverse radiation effect on the brainstem, also 3 to 4% of the time (but only when the tumor is in contact with the brainstem). The delayed risks of radiation include the induction of new tumors (meningiomas in particular, but also the risk of malignancy) and typically does not occur until 7 or more years after radiation treatment is completed.

In addition, because the tumors are not killed by the radiation treatment, some tumors recover from the effect of radiation and resume growth after a period of time. The radiation failure rate is very low during the five years following treatment (~5%) but may be as high as 15 to 20% at 10 years.

The recovery from surgery occurs in three stages: in the hospital, after discharge but before the wound has fully healed, and after suture removal (at two weeks post op). After surgery you can expect to spend 3 to 4 nights in the hospital, depending on how dizzy or off-balance you feel. It is very common to be dizzy after acoustic neuroma surgery and recovery of your balance is important prior to discharge. That having been said, you may still feel a little off balance (akin to just disembarking from a boat) for the week or two following surgery.

For the following ten days or so after discharge (ie when at home but before the sutures have been removed), we encourage you to be as active as you can tolerate, especially walking. You will not need any special nursing care or help with your activities of daily living, though it is probably prudent not to be alone.

Until the sutures are removed we ask that you avoid straining (to minimize the risk of CSF leak), so do not lift anything heavier than ten pounds, take a stool softener, and avoid bending over at the waist.

Wash the wound and shampoo your hair daily after discharge from the hospital. Sutures will be removed approximately two weeks after the day of surgery.

In comparing radiation and surgery, it is important to understand that aside from the risk/benefit ratio calculation, there is a very fundamental difference in the goals of treatment between radiation and surgery. Specifically, the goal of radiation is to "control" the tumor (i.e., prevent growth) whereas the goal of surgery is to remove the tumor. Because radiation treatments do not kill the tumor, and because hearing loss does not depend on tumor growth, the tumor continues to adversely affect hearing after radiation treatment. So for patients with excellent hearing for whom hearing preservation is technically feasible, consideration may be given to surgery rather than radiation. In addition, some tumors recover from the radiation treatment and resume growth- sometimes years after radiation has been given. This is called radiation treatment "failure." The rates of radiation treatment failure are low, but as high as 15 to 20% at ten years. So for older patients radiation tends to be a safer bet than for younger patients, all things being equal.

The main advantage of radiation is that it is less likely to cause facial weakness compared to surgery. In most published series of radiation treatment, the risk of facial nerve injury is as low as 1 to 2% and as high as 3 to 4%, though in our experience facial weakness after radiation is seldom a complete facial paralysis. In experienced hands, the risks of permanent facial weakness following surgery is roughly twice the risk as that of radiation. In absolute terms, however, the risk to the facial nerve is small either way (<5% for all but very large or giant tumors).

We do not advocate for radiosurgery on initial diagnosis, or in the absence of documented growth on follow up MRI. If a tumor is not growing — and the data suggest that up to one-half of tumors diagnosed do not grow in the first five years of diagnosis — there is strictly speaking no benefit from radiation treatment (because the goal of radiation treatment is to stop growth). Because no treatment is without risk, radiation for non-growing tumors is in our opinion not justified. Some authors suggest that the pre-emptive treatment with radiosurgery is more effective than treating after growth has commenced. However, we feel the overall tumor control rate in the literature takes into account that growing tumors may be less responsive to radiosurgery. Finally, we know that late treatment failure after radiosurgery occurs in up to 15 to 20% of patients. For this reason, we feel that it is prudent to defer radiosurgery so as to maximize the time period of tumor control overall.

At UCLA, we consider surgery to generally be an excellent option for small tumors. And although this may be controversial, for patients with small tumors and excellent hearing we believe surgery to generally be the treatment of choice.

Balance problems — whether vertigo, dizziness, or imbalance — are seldom the predominant complaints of patients with acoustic neuroma, perhaps occurring in 5 to 10% of patients. Hearing loss is much more commonly the reason that the tumor gets diagnosed. However, many if not most patients with acoustic neuroma will endorse balance problems of a more minor nature-especially veering to one side (typically to the side of the tumor). In those rare instances where balance is the predominant or chief complaints, we believe surgery may have a better chance at returning balance function to normal.

After surgery, it is very common to feel off-balance during the early phases of recovery. If balance problems persist after the two week follow up visit, we have found that vestibular rehabilitation therapy (PT) has been beneficial. It is a reasonable expectation to return to fully normal activities including sports etc when fully recovered.

LAX has convenient flights to virtually every city in the United States. The Ronald Reagan UCLA Medical Center campus is 45 minutes away from the airport. There are several on-campus options for lodging for you and for your family. You should anticipate spending two weeks in Los Angeles total.