An acoustic neuroma (also known as a vestibular schwannoma) is a benign tumor originating from the balance nerves, the nerves that carry balance signals from the inner ear to the brain. Acoustic neuromas are located deep inside the skull and are adjacent to vital structures such as the brain stem. The first symptoms a patient with an acoustic neuroma usually notices are ringing in the ear, hearing loss, and sometimes dizziness. The hearing loss will usually be much more severe on the side affected by the tumor and it is this “asymmetry” in the hearing that usually alerts the doctor to the possibility of an acoustic neuroma, as the hearing in the opposite ear will not be affected by the tumor. Generally, the tumor affects the hearing in one ear only, except in the case of a rare condition called neurofibromatosis type II, in which acoustic neuromas may involve both left and right balance nerves. As the acoustic neuroma enlarges, it may put pressure on the brain stem and can involve other surrounding nerves and structures. If allowed to continue, this pressure on the brain is can be fatal, although this is extremely rare. In most patients, acoustic neuromas grow slowly over a period of years. In some, the rate of growth is more rapid, however. Thus the symptoms may develop slowly or more rapidly.
An acoustic neuroma is diagnosed with an MRI scan of the brain. This is generally ordered when a patient has hearing loss that is significantly poorer in one ear than the other on a hearing test or when the patient has had a sudden decrease in the hearing in one ear. Other causes for the hearing loss, such as an ear infection, should be ruled out first. Your doctor may order an MRI of your brain if he believes there is a possibility of an acoustic neuroma. If you are diagnosed with an acoustic neuroma, your doctor will likely refer you to a specialist, a neurotologist (hearing and balance specialist) like Paul F. Shea, M.D., at the Shea Ear Clinic, who will discuss the options for treatment with you.
Risks and complications of acoustic neuroma treatment vary with the size and rate of growth of the tumor. In general, the larger the tumor, the more difficult to remove and the more serious the complications. The removal of an acoustic neuroma, whether large or small, is a major surgical procedure, with the possibility of serious complications, including death. Acoustic neuromas are classified as small, medium, or large.
Small (less than 1 centimeter) – A small acoustic neuroma is still confined within the bony canal that extends from the inner ear to the brain. The hearing, balance, and facial nerve, as well as the blood vessels that supply the inner ear, pass through this canal.
Medium (1 centimeter to 2.5 centimeter) – A medium-sized acoustic neuroma extends from the bony canal into the brain cavity, but is not putting pressure on the brain stem.
Large (more than 2.5 centimeter) – A large acoustic neuroma extends out of the bony canal into the brain cavity and is large enough to begin to put pressure on the brain stem.
If you are diagnosed with an acoustic neuroma, you and your surgeon will make the decision of which treatment is best for you. This decision will be based on a number of factors, including your age, general health, and how much hearing you still have on the affected side. There are three treatment options for acoustic neuromas.
All treatments for acoustic neuroma involve the possibility of further loss of hearing, ringing in the ear, loss of balance, and facial nerve weakness (drooping of the face) or paralysis of the face. Complications from anesthesia, headaches, spinal fluid leakage, bleeding, infection, and death are much less likely complications of surgery. However, the most likely complication is usually facial nerve weakness or paralysis. For this reason, surgical approaches and techniques are designed to minimize this possibility. At the Shea Ear Clinic, this is accomplished through the use of a team in which a neurotologist like Paul F. Shea, M.D. or Brian J. McKinnon provides the surgical approach, an experienced neurosurgeon removes the tumor, and the neurotologist closes the wound at the end of the procedure. Facial nerve function is continuously monitored throughout the procedure by an audiologist and an alarm is heard if irritation of the nerve is detected while the surgeon is removing the tumor. This minimizes the likelihood of facial weakness following the procedure.
The primary objective in surgery is to remove the acoustic neuroma to preserve life. A secondary objective of operation is to preserve as many vital structures as possible. For many, a completely normal life results following operation. Some patients experience physical disabilities, including permanent hearing loss in the affected ear, loss of balance and possibly weakness of the face on the affected side. For a few patients, maximum degrees of physical disability may persist. However, the single biggest factor that determines the success of surgical resection of acoustic neuroma remains the skill and experience of the surgical team. This skill and experience is responsible for the excellent results seen at the Shea Ear Clinic with surgical resection of acoustic neuroma.
At the American Neurotology Society Spring Meeting, Dr. Brian J. McKinnon’s team presented their latest ongoing research on the development of a novel cochlear implant thin film array electrode.
Throughout the course of his life, Dr. John Shea Jr. has made major historical breakthroughs and advancements in medicine. Recently, Shea donated 406 papers, including more than 300 published articles, to the Memphis Public Library’s Memphis Room..