Treatments for Acoustic Neuromas

Treating acoustic neuromas can be complex because of the anatomy and other individual factors involved. At UT Southwestern, we use a multidisciplinary approach involving a neurotologist (ear specialist), a neurosurgeon, and, when appropriate, a radiation oncologist to improve outcomes. Treatments include observation, radiosurgery (radiation therapy), and surgery.

Observation

Small tumors and some medium tumors can be observed with serial MRIs. If no tumor growth is seen, an annual MRI is required to make sure the tumor does not show growth. If the tumor has grown, further treatment is indicated.

Observation is not recommended for young patients or for patients with large tumors. Hearing loss is possible during the observation period and can be sudden in some cases.

Radiosurgery

Radiosurgery is the use of radiation in a very precise manner. The goal of treatment is to stop tumor growth. Generally, the tumor should show signs of growth via multiple MRIs before the tumor is treated with radiosurgery.

The procedure is performed on an outpatient basis and is well tolerated, although some patients experience temporary headache and nausea.

The risks of radiosurgery include continued tumor growth, facial numbness, hearing loss, dizziness, ringing in the ear, facial paralysis or twitching (rare), and fluid buildup around the brain.

If the tumor needs to be removed after radiosurgery because of continued tumor growth, complications (including facial weakness) tend to be more common. Also, there is a small risk of the tumor turning malignant (cancerous); this risk is estimated to be 1 in 1,000 cases over a 30-year period.

Surgery

Because of the anatomical complex involved with the surgical removal of an acoustic neuroma, we use a team approach to treatment, including a neurotologist, neurosurgeon, and audiologist.

Hearing preserva­tion may be attempted in patients with normal or near-normal hearing and small tumors.

We determine the most appropriate surgical approach based on multiple factors including tumor size, tumor location, and hearing status. Depending on the tumor location and type of surgery, we monitor facial nerves and hearing nerves during the procedure.

Translabyrinthine Approach

This is the most common approach for removing an acoustic neuroma. An incision is made behind the ear, and the bone behind the ear is removed. Next, the labyrinth is removed, allowing a wide view of the tumor.

Because the labyrinth is removed, total hearing loss is expected; however, with this approach, the brain does not require retraction and the largest tumors can be removed. Fat from the abdomen is used to fill in the surgical defect.

Middle Fossa Approach

We use the middle fossa approach to remove small tumors in patients with good hearing. An incision is made above the ear, and a small piece of the skull is removed that will be placed back with small titanium plates. The temporal lobe of the brain is retracted, and the bone over the internal auditory canal is removed, allowing access to the tumor that is then removed. The goal of the middle fossa approach is hearing preservation, which is achieved in approximately 60 percent of cases.

Retrosigmoid Approach

The retrosigmoid approach is also used for small to medium tumors that have developed primarily in the brain cavity rather than in the internal auditory canal. We make an incision behind the ear and remove a small piece of the skull, allowing a wide view of the brain cavity. We then remove the tumor. Hearing preservation is sometimes possible with the retrosigmoid approach.

Total versus partial removal

Total removal of a tumor is always the initial goal of surgery. If the tumor is very stuck to the facial nerve or other vital structures, a small piece of tumor may be left behind to prevent complications. These small tumor remnants rarely grow; however, it is important to get an annual MRI to make sure.

Hearing Impairment

The natural course of an untreated acoustic neuroma is hearing loss in the affected ear. Surgery or radiosurgery can also result in hearing loss. Many patients adjust well to hearing in only one ear. Other patients are more bothered with hearing loss and can consider a few options.

One options is to wear a CROS (contralateral routing of sound) hearing aid, which consists of a hearing aid in the poor ear that transmits sounds to a hearing aid in the better ear.

A bone-anchored hearing device is a surgically implanted abutment that attaches to an external sound processor. The sound is then routed through the bones of the skull into the good ear. The surgical procedure takes about 45 minutes and is performed as a day surgery.