Acoustic Neuroma Symptoms, Diagnosis, and Treatment

Acoustic neuroma is a benign tumor affecting the nerves that run from the inner ear to the brain. Normal healthy nerves are covered by a layer of cells called Schwann cells which function the same way that rubber or plastic coating on electrical wires work; providing insulation and support for nerve impulses. When these cells begin to grow and multiply at an abnormal rate, an acoustic neuroma can occur.

Prevalence

Acoustic neuroma occurs only in about 2 out of 100,000 people when there are no other precipitating factors. The most common non-genetic reason for developing an acoustic neuroma is auditory trauma and there is some belief that low-dose radiation for procedures of the head and neck at a young age may increase your risk. While there have been rumors that long-term cell phone use can be associated with acoustic neuroma, research does not support this rumor.

Acoustic neuroma is more prevalent if you have neurofibromatosis type 2 (NF2). If you are diagnosed with NF2, your risk increases to 2 out of 10,000 people. In either case, acoustic neuroma tends to occur between 50 to 70 years of age.

Symptoms

Acoustic neuroma inhibits the normal function of the nerves responsible for hearing and balance. Symptoms of acoustic neuroma include:

• hearing loss on one side
• vertigo
• tinnitus

If the tumor presses against the facial nerve, symptoms may also include:

• facial numbness
• facial weakness
• facial paralysis

While acoustic neuroma is a slow-growing tumor, if it is untreated it can become so large that it pushes against vital brain structures and may become life-threatening.

Diagnosis

Diagnosis of acoustic neuroma can be difficult (especially if the tumor is small) because the symptoms coincide with many other inner ear disorders. Some of the most useful tests used to diagnose this condition are:

• Audiogram
• CT scan
• MRI

MRI is the preferred method of testing as it can be useful in identifying small tumors (2 mm in size or larger) when used with gadolinium contrast. CT may be used in seeing tumors that are larger than 2 cm.

Treatment

Treatment may involve surgical removal of the tumor. However, if the tumor is small and asymptomatic, the patient and doctor may opt to monitor the tumor. This is also the case if the patient is not a good candidate for surgery such as elderly patients who have a history of heart and lung disease.

The surgical excision of the tumor carries several risks including the risk that the nerves surrounding the tumor may be damaged. This is particularly true if the tumor is very large. Other options for treatment involve radiation therapy or radiosurgery. Both of these treatments are aimed at reducing the size of the tumor.

In an attempt to reduce the risk of injuring nerves around the tumor, some surgeons may opt to do a partial tumor resection to remove the majority, but not all, of the tumor. Following the surgery, targeted radiation therapy can be done to arrest the growth of the rest of the tumor.

Failure to treat acoustic neuroma can lead to permanent hearing and balance problems. If the tumor is small, your surgeon may want to delay surgically removing the tumor and will follow with an MRI every 6 to 12 months. Delaying treatment too long though may result ​in irreversible damage. Having an open discussion about risk vs. benefit of delaying surgery with your surgeon is warranted before making any decisions.

Also known as: acoustic neurinoma, vestibular schwannoma, auditory tumor