An acoustic neurinoma, also known as an acoustic neuroma or vestibular schwannoma, is a slow-growing noncancerous tumor. The tumor is typically intracranial and develops on the principal nerve that connects the inner ear and the brain. As the acoustic neurinoma grows, the resulting pressure on the vestibulocochlear nerve can affect a person’s hearing and balance. Hearing loss, tinnitus, and unsteadiness can all be indications of an acoustic neurinoma. Common treatment options are monitoring, surgery, and radiation.
Medical researchers believe that tumors on the vestibulocochlear nerve are the result of a malfunctioning gene on the 22nd chromosome. This gene makes a protein that regulates the growth of Schwann cells that sheathe the nerve. When the gene malfunctions, the growth of these cells is not controlled properly, and tumors can form. The precise cause of the malfunction is not known, but scientists believe that it may be an inherited condition in at least half the cases.
The symptoms of an acoustic neurinoma result from the tumor putting pressure on the brain or nearby blood vessels and nerves. The tumor will typically cause gradual hearing loss in the ear on the side of the head where the growth is located. The affected ear may also ring continually. A loss of balance, vertigo, and facial numbness are other signs.
An early diagnosis and treatment can help prevent the acoustic neurinoma from growing big enough to cause serious symptoms. The majority of tumors are visible on magnetic resonance imaging or computerized tomography scans of the head. Hearing, balance, and neurological function tests like electronystagmography may also be performed to confirm a diagnosis.
Very small tumors without symptoms that do not appear to be growing or that are growing extremely slowly will likely be monitored without requiring immediate medical intervention. The doctor will have the patient return every six months or annually for hearing and imaging tests. Treatment becomes necessary only when symptoms manifest or when the tumor starts to grow faster.
When an acoustic neurinoma requires treatment, surgical removal and radiation are the most common options. Radiation is used when the tumor cannot be removed surgically without damaging other tissues. Image scans help determine the tumor’s location, and a radiation beam is applied to stop growth. The effect of radiation may not be evident for months.
The goal of surgery is to remove the tumor without damaging the facial nerve as well as hearing and other local tissues. The neuroma is usually removed through an incision in the skull or through the inner ear. Recovery can take at least a month, and the procedure will likely require a hospital stay of approximately four days. If any nerves or tissues are damaged during surgery, the complications can be serious.
Men and women in their fifties and sixties are most likely to develop an acoustic neurinoma. Although the tumor can sometimes grow rapidly, pressing on the brain and affecting vital functions, this is an uncommon scenario. This type of neuroma is not a common cause of hearing loss. Individuals experiencing hearing loss, ringing in the ears, or balance problems should consult with a medical professional.