Acoustic Neuromas ( Also known as vestibular schwannoma)

 

An acoustic neuroma is a benign, usually slow growing tumor that grows on the 8th cranial nerve – the vestibule-cochlear nerve.  This nerve is responsible for hearing and balance.  This tumor usually starts growing in the internal auditory canal – which is a space in the skull which allows nerves and blood vessels to pass from the external ear to the brain.  As the tumor grows, it spreads out toward the inside of the skull, pushing the normal brain out of the way. It usually doesn’t invade the brain. 

 

Rarely,  Acosutic neuromas are associated with a genetic condition called neurofibromatosis type 2. These cases usually have acoustic neuromas on both sides, and they grow faster than cases not associated with neurofibromatosis.  For the majority of cases, no cause is identified.

 

Early symptoms include loss of hearing and/or problems with balance.  Hearing loss is usually gradual over years and on one side only (except when associated with neurofibromatosis), however, sometimes the hearing loss is sudden.   This hearing loss is usually accompanied by  tinnitus – which is the perception of sounds in the affected ear, sometimes described as ringing, ticking, clicking or wooshing sounds.  Balance problems are usually ignored at first because your body compensates using the other ear.

 

As the tumor grows, it starts pressing on other nerves and blood vessels which can cause more problems.  The facial nerve and trigeminal nerve run alongside this area.  These nerves control movements and feeling in the face, which may result in numbness or strange sensations in the face, and spasms of the face.  If left untreated, the tumor can grow large enough to put pressure on the brainstem which can cause death.

 

Acoustic neuromas used to be invariably fatal, but now with advances in neurosurgery and radiation techniques, the majority of  cases can now be controlled.  The tumor is located in a very delicate area, and it is not uncommon to have injuries to the nerves, which may result in permanent deafness in the area, loss of balance on that side, or ever problems with the facial and trigeminal nerves, which can result in paralysis of facial muscles or pain in the face.

 

Diagnosis is usually made by an MRI with contrast. These appear in a very characteristic way on MRI which allows for a diagnosis to be made based on MRI alone. 

There is a controversy over the best treatment.  With this tumor type, it is necessary to get opinions from doctors who treat a lot of these tumors (having treated at least 50 acoustic neuromas), as well as to get opinions from doctors who treat it with surgery and doctors who treat it with radiation. 

Treatment can be either:

1. Observation.  Since this is usually a slow growing tumor, if the symptoms are not severe and the tumor is not pressing on anything important, it is acceptable to do nothing and just see what happens.   In elderly or sick patients, there is a chance that the tumor will never grow to a size that causes problems.
2. Surgery. Surgery is considered the gold standard of care.   If the tumor is removed completely, it rarely grows back.  With new microsurgery techniques, the chances of preserving useful hearing is pretty good.  
3. Radiation.  In the last few years, radiation has become an acceptable treatment option for acoustic neuromas.  Stereotactic radiosurgery (a one day treatment) or fractionated stereotactic radiotherapy (multiple doses spread out over a few weeks) are ways to focus the radiation energy on the tumor without damaging the surrounding normal structures.  There are many machines used – gamma knife, cyberkinfe, novalis system, Linac, X-Knife, Trilogy, peacock system and more.  Each machine has advantages and disadvantages, but the most important factor in a successful treatment is the experience and training of the doctor.  Radiation does not make the tumor go away – it usually stops any further growth, and the tumor slowly shrinks over a long period of time.   The advantage of radiation is that it is much easier for the patient. No recovery time, minimal immediate side effects.  The downside is that there is a small – but real – chance of developing long term side effects, including the development of another tumor. 

You will be getting a lot of opinions from different people on the merits of selecting radiation or surgery – or even which type of radiation. My own personal thoughts (I am not an MD, but I have run the Musella Foundation for over 9 years and talked to many patients):   If the tumor needs treatment, the older the patient, the smaller the tumor and the worse health of the patient would lead me to select radiation over surgery. For a young healthy patient, or if the tumor is large and pressing into the brain, I would select surgery.  Again, you need to be treated by a very experienced team.  Feel free to contact us for referrals to doctors in your area.

 

 

Links on Virtualtrials.com:

• Acoustic Neuromas – by Dr Michael Shulder
• Acoustic Neuromas By Dr Rick Friedman 
• Radiation For Brain Tumors by Dr. Naren Ramakrishna
• Radiosurgery - a Noninvasive Brain Tumor Treatment Option (31:45) – by Dr. Susan Pannullo
• Novalis Shaped Beam Surgery  
• Advances in surgery for brain tumors by Dr. Stephen A. Tom,
• Radiation Therapy and Radiosurgery For Brain Tumors – by Dr. James Fontanesi

 

 

Links to outside resources:

• Acoustic Neuroma Association http://www.anausa.org
• International Radiosurgery Association http://www.irsa.org
• Elekta (Gamma Knife) http://www.elekta.com/
• Accuray (Cyberknife) http://www.accuray.com/
• Varian (Trilogy) http://www.varian.com/orad/prd171.html
• Radionics (X-knife) http://www.radionics.com/products/rt/xknifert.shtml

 

Medical Articles:

• Patient outcomes after vestibular schwannoma management: a prospective comparison of microsurgical resection and stereotactic radiosurgery. 
• Fractionated stereotactic radiotherapy for acoustic neuroma : single-institution experience at the princess margaret hospital.  
• Surgery for large vestibular schwannomas: how patients and surgeons perceive quality of life.

 

 

Online support groups: 

We run the Acoustic Neuromas online support group!

This page was created on 03/04/2007 and last updated on 03/23/2007