An acoustic neuroma is a benign (noncancerous) tumour that typically grows very slowly in the head. The tumour will develop on a portion of the eighth cranial nerve which is just adjacent to the brain. This specific nerve runs from your brain to the inner ear. An acoustic neuroma, which is often referred to as a vestibular schwannoma, is probably the most common type of brain tumour. Some people may only ever suffer from an extremely small acoustic neuroma which would normally cause no problems whatsoever.
The main symptoms of acoustic neuromas will develop from the actual tumour pressing against the cranial nerves. Although the size of the tumour may not make much difference, as it grows it is likely to cause further symptoms. In general if the tumour is less than 6/10 of an inch, it is not likely to cause any symptoms. However, some tumours are known to grow as large as 2.5 inches. The main symptoms that you will experience include:-
Tinnitus or a ringing in the affected ear, dizziness or vertigo, a gradual loss of hearing, although in many cases it may come on suddenly, a loss of balance and a facial numbness and weakness. In some of the rarest of cases, an acoustic neuroma may actually grow large enough that it will compress the brainstem and this, in turn, may even be life-threatening. It is advisable that you consult with your doctor if you develop ringing in your ear, hearing loss, dizziness, or if you begin to have trouble with your balance. The earlier you can diagnose an acoustic neuroma, the more likely that you will be able to stop the tumour from growing large enough to cause any serious problems.
The eighth cranial nerve, or vestibulocochlear, actually has three branches which will transmit information from your inner ear to the brain. The superior vestibular branch and the inferior vestibular branch are known to control your balance, whereas the cochlear branch will carry sound. The majority of acoustic neuromas are known to develop on one of the vestibular branches. Unfortunately, the actual cause of acoustic neuromas is still unknown. However, in some cases a tumour may be an indication of neurofibromatosis 2. This can best be described as a genetic disorder whereby tumours grow on the vestibulocochlear nerve.
Acoustic neuromas most commonly occur in people aged between 30 and 60. There is evidence that suggests that if a person has been exposed to very loud noises or even heavy cell phone use, they have a greater chance of developing an acoustic neuroma. However, this evidence has been gathered from a number of studies and is still inconclusive. The complications that an acoustic neuroma may cause include permanent hearing loss, difficulties with balance and facial numbness and weakness. If a tumour is excessively large it may, as mentioned, press against your brainstem and this may prevent cerebrospinal fluid flowing between your brain and spinal cord. This may cause the fluid to build up in your head which will cause an alarming amount of pressure inside the skull.
As the symptoms of an acoustic neuroma typically develop very slowly, it can often be hard for your doctor to actually detect a tumour in its early stages. Acoustic neuromas as are most often found when a patient is being screened for another condition. To diagnose an acoustic neuroma your doctor will initially ask you a few questions about your symptoms, conduct an exam and they are also likely to perform a magnetic resonance imaging (MRI) or a computerised tomography (CT) scan of your head. An audiologist will conduct a hearing test where they will present you with a series of sounds and tones. You will usually be asked to indicate each time you hear a sound. Other tests that may be performed include an electronystagmography, which will evaluate your balance and a brainstem auditory evoked response (BAER), which will check your hearing and neurological functions by placing electrodes on your scalp and earlobes.
There are 3 separate options for treating an acoustic neuroma. These include monitoring for a small acoustic neuroma that has yet to show any symptoms and is either not growing or growing very slowly. Your doctor may recommend monitoring of the tumour by having a regular imaging scans and tests. The next form of treatment is stereotactic radiosurgery which will involve delivering radiation directly to the tumour without having to make an incision into the head. The tumour can be pinpointed by the use of imaging scans and then your doctor will be able to plot exactly where they wish to radiation beams to go.
The main purpose of radiosurgery is to completely stop a tumour from growing. The final form of treatment is surgical removal which will involve removing the tumour and preserving the facial nerve. The tumour will typically be removed during surgery and via an incision in your skull. It is performed under anesthesia and you will usually need to stay in hospital for at least 4 to 6 days after surgery. Complete recovery may take up to 6 weeks.