09/07/17 - Salem, MA - What is an Acoustic Neuroma?
An acoustic neuroma (Vestibular Schwannoma) is a benign tumor that is produced from the nerves that supply the inner ear. The tumor is created from the overproduction of the cells that wrap the nerve fibers. Loss of balance and loss of hearing on one side are usual results of an acoustic neuroma formation. In certain instances, the tumor can affect the function of the trigeminal nerve, Cranial Nerve V, or the facial nerve, Cranial Nerve VII, resulting in symptoms such as: facial numbness, facial weakness, or even paralysis. If the tumor is allowed to grow large enough, it can begin to press against the brainstem and cerebellum, thereby becoming life-threatening.
Treatment of acoustic neuroma can be achieved through surgical removal, radiation therapy, and monitoring. In either approach, early diagnoses is important. In most instances, the tumor is removed surgically, though the exact procedure can vary depending on the size of the tumor and the current level of hearing. If the tumor is small, it can be possible for hearing to be preserved and the other symptoms may improve. If the tumor is large, surgical intervention can be more difficult as the tumor may have damaged Cranial Nerves V and VII and, if very large, can affect other nerves and even brain structures. Removal of large tumors that have damaged Cranial Nerves V and VII may cause the related symptoms to worsen, as portions of those nerves may need to be removed with the tumor.
In some instances, it may be determined that radiation therapy, gamma knife, may be the best course to reduce the size or limit the growth of the tumor. This is more often the case with elderly patients, patients in poor health, patients who have a tumor in both ear canals, or patients who only have preserved hearing in the affected ear. In certain cases, it may be deemed best to monitor the patient rather than risk surgical intervention, again this is the case for elderly patients and patients in poor health.
Approximately 8% of all tumors in the skull are unilateral acoustic neuroma, which is an acoustic neuroma affecting only a single ear. This comes to approximately one out of every 100,000 individuals per year. It is believed that acoustic neuroma form as a result of the loss of the function of a gene on chromosome 22. It is further believed that the gene on chromosome 22 produces a protein that governs the growth of the cells that normally wrap the nerve fibers, Schwann cells. When the function of the said gene is lost, the production of the Schwann cells is uncontrolled, thereby resulting in the acoustic neuroma formation.
Information courtesy of National Institutes of Health (NIH), National Institute on Deafness and Other Communication Disorders (NIDCD). For more information, please visit: http://www.nidcd.nih.gov/health/hearing/pages/acoustic_neuroma.aspx.