Acoustic Neuroma Surgery

What is Acoustic Neuroma?

Acoustic neuroma (also known as vestibular schwannoma or acoustic neurilemmoma) is a benign tumor of the acoustic nerve. It is non cancerous and can be treated by radiation or surgery. In fact acoustic neuroma surgery is recommended when the tumor becomes too large. Two of the most frequent symptoms is hearing loss (in the affected ear) and dizziness or balance problems.

One of the issues with this type of tumor is that it is difficult to diagnose. At first these tumors may not cause any problems but as they get larger (tumors are classified according to its size in: small, less than 1.5 cm; medium, 1.5 cm to 2.5 cm; or large, more than 2.5 cm) they cause hearing and balance problems and may require treatment. Part of the problem with vestibular schwannomas is that they go undetected for a long time since hearing loss and dizziness are common symptoms for a variety of middle ear problems. A tumor may not be in the mind of a doctor when a patient has these symptoms. Usually, acoustic neuromas are discovered when a MRI (magnetic resonance) is performed.

Acoustic Neuroma Surgery

The main recommended treatment for acoustic neuroma depends on the size of the tumor. Basically, there are three options:

1.-Observation

Here the treatment option is “watch and wait.” This is done when the tumor is small. MRI’s are performed periodically and, if the tumor does not grow it is left as is. If the tumor grows then other types of treatments may be required.

2.-Radiation

Radiation can be delivered to the tumor either in a single session or in multiple sessions. In both cases general anesthesia or hospitalization is not required. The purpose of radiation therapy is to stop tumor growth by killing the cells of the tumor.

3.-Acoustic Neuroma Surgery

There are several options of surgery. The basic idea is to remove part or all of the neuroma. Microsurgical techniques and instruments, as well as an operating microscope are used to remove the neuroma with great precision. The risk of this type of intervention is damage to other nerves (such as the facial nerves) with complications that will surface later.

There are three main approaches: middle fosa craniotomy (a small window of bone is removed above the ear canal), retrosigmoid/sub-occipital (an opening in the skull behind the mastoid part of the ear near the back of the head on the side of the tumor), and translabyrinthine (involves the removal of the mastoid bone and some bone of the inner ear). The retrosigmoid approach is performed when preserving hearing is a goal (although there is latent risk of damaging the nerve) and the translabyrinthine approach is performed when hearing loss is complete or if preservation of hearing is not a goal.

References:

Medline Plus (https://www.nlm.nih.gov/medlineplus/acousticneuroma.html)

Acoustic Neuroma Association (https://www.anausa.org)