An Auditory Tumor or Acoustic Neuroma or Vestibular Schwannoma is a non-cancerous (benign) growth that arises on the eighth cranial nerve. The eighth cranial nerve connects the inner ear to the brain; it is called the vestibular cochlear nerve. Acoustic neuroma does not spread to other parts of the body. It can however damage nearby nerves as it grows.
Causes of Auditory Tumor / Acoustic Neuroma
There are two forms of acoustic neuroma:
a) A sporadic form: Majority of acoustic neuromas are the sporadic form. The exact cause is unknown.
b) A form of acoustic neuroma is associated with a syndrome called neurofibromatosis type II (NF2). NF 2 is a rare inherited disorder characterized by the growth of noncancerous tumors in the nervous system.
Exposure to high doses of radiation is a known risk factor for vestibular schwannoma.
Symptoms of Auditory Tumor / Acoustic Neuroma
A gradual loss of hearing in one ear is one of the earliest symptoms of acoustic neuroma. However, this is often attributed to normal changes of aging and hence the diagnosis is often delayed. Acoustic neuroma develops gradually at a slow rate of roughly 1-2 mm each year. Symptoms usually start after age 30.
Hearing loss is often associated with tinnitus, i.e. ringing in the ear.
A feeling of dizziness called vertigo is often present.
Other symptoms that are less common include:
Difficulty understanding speech
Loss of balance
Numbness in one ear, or part of the face
Pain in one ear, or part of the face
Weakness of the face
Diagnosis of Auditory Tumor / Acoustic Neuroma
A definitive diagnosis of acoustic neuroma is made using an MRI of the brain. Other tests employed include:
Hearing tests (audiology tests)
Test of equilibrium and balance (electronystagmography)
Test of hearing and brainstem function (brainstem auditory evoked response)
Treatment of Auditory Tumor / Acoustic Neuroma
Treatment depends on the size and location of the neuroma, age and health of the patient. Small tumours that produce few or no symptoms are usually followed up with regular imaging (MRI); this is mostly done in older patients.
Surgery is done to remove tumours that are-
Pressing on the brain
Surgery done to remove acoustic neuroma may have associated complications such as damage to adjacent structures, mainly the nearby nerves.
In cases where surgery is not possible, stereotactic radiosurgery is done. This is a form of radiation therapy that focuses high-powered x-rays on a small area.
Prognosis and Complications of Auditory Tumor / Acoustic Neuroma
An acoustic neuroma maybe completely removed by surgery. Patients with small tumours may not develop any complications. Those with large tumours may however develop permanent weakness of the face after surgery. The application of radiation is also associated with nerve damage, loss of hearing, and paralysis of the face.