Do you have trouble maintaining your balance on a regular basis? Do you feel a ringing in your ears for no apparent reason? If your answer is yes to both of these questions, you may have an acoustic neuroma.

The Acoustic Neuroma is a tumor that forms on the brain’s eighth cranial nerve, which is also known as the acoustic nerve. This nerve, along with the sensory cells of the inner ear, is responsible for sending information to the brain. It is made up of the cochlear nerve, which carries information about hearing, and the vestibular nerve, which carries information about balance.

In adults, the acoustic neuroma turmor is usually present as a solitary tumor that originates in the nerve, specifically from the vestibular portion of the eighth nerve which is found within the internal auditory canal. As the tumor increases in size, it usually extends into other areas of the brain, mainly the posterior fossa to occupy the angle between the cerebellum and the cerebellopontine angle. If the tumor grows large enough, it can cause obstruction of the CSF and increased intracranial pressure.

According to recent estimates, there are about 3,000 cases of acoustic neuroma diagnosed in the United States each year, which translates into about one for every 100,000 people. It usually occurs when people reach their fifties and sixties, and it affects both men and women equally.

Among the earliest symptoms of acoustic neuromas are loss of hearing or deafness, difficulty keeping one’s balance and an altered gait, vertigo, nausea and vomiting, and a feeling of pressure in the ears. In addition, over 80% of people suffering from an acoustic neuroma are plagued by “tinnitus,” which is characterized as a high-pitched ringing in the ears similar to the hissing sound of a steam kettle.

The larger acoustic neuromas may affect other cranial nerves and lead to facial weakness, sensory impairment as well as loss of taste and loss of sensation in the face and mouth.

An enhanced CT scan usually detects acoustic neuromas, which are usually 2.0 cms in diameter. The smaller acoustic neuromas are detected with an MRI. Audiology and vestibular tests are also used in diagnosis.

The most common treatments for acoustic neuromas are surgical removal or radiation therapy. In most cases and since these tumors tend to grow slowly, doctors recommend conservative treatment beginning with an observation period or “watchful waiting.” These involve annual MRI monitoring to gauge the tumor’s growth. It is important to note that 45% of acoustic neuromas do not grow much over a 3-5 year period of observation, if detected early enough. In rare cases, these tumors have even started to shrink spontaneously without any treatment. Observation is a especially important considering that surgical and radiation treatments pose great danger to the hearing in the affected ear.

Surgery often successfully removes the tumor without occurrence, but there is a high incidence of complications and ill effects on quality of life, such as continued problems of severe imbalance, vertigo and dizziness. Patients may be walking after the first week of surgery, but their sense of balance may never be the same again. Some patients report 50% loss in hearing in the affected ear. There is also a fear of the facial nerve being severed during surgery, which would leave the face disfigured. As a general rule, the larger the tumor, the higher the risk of complications.

There are several types of radiation therapy, and the most popular one is gamma knife radiosurgery, wherein 201 beams of gamma radiation are concentrated on the tumor in a single session to damage the tumor and prevent it from growing further or even shrinking it.