What is Acoustic Neuroma?
Acoustic Neuroma (also called vestibular schwannoma, acoustic neurinoma, or acoustic neurilemoma) is a benign slow growing tumor that forms in the inner ear. The noncancerous growths occur when the body produces an excessive amount of Schwann cells, which normally surround nerves to form a protective and insulating layer. Acoustic neuromas form around the nerves that assist with balance and hearing and can cause patients to have difficulty in these areas. Symptoms of the condition include hearing loss usually on one side, dizziness, problems with balance, and ringing (AKA tinnitus) in the ears. It is usually diagnosed on MRI scan of the brain after an abnormal hearing test.
What Causes Acoustic Neuroma?
Most acoustic neuromas are caused by a malfunctioning chromosome 22, meaning that the condition is genetic. It appears that the tumor arises as a result of the loss of a tumor-suppressor gene on the long arm of chromosome 22. The annual incidence is 0.78-1.15 cases per 100,000 population, resulting in approximately 2280 new cases per year in the US. Patients usually become symptomatic after age 30. The incidence of acoustic neuromas is increased in neurofibromatosis with bilateral acoustic neuromas being a characteristic of neurofibromatosis type 2.
“Patients who recieved radiosurgery for acoustic neuroma at the JD Lipani Radiosurgery Institute have had arrest of tumor growth and hearing preservation in 100% of cases. No patient experienced facial nerve injury.”
– Dr. Lipani
Acoustic Neuroma Treatment
If the tumor is small and is not causing symptoms, the only treatment necessary may be monitoring with hearing tests and MRI scans every six months to make sure that the tumor has not grown. If the tumor does cause symptoms, treatment is usually indicated to prevent further problems. Treatment options generally include surgery, radiation therapy, or radiosurgery, a non-invasive or knifeless procedure that uses precision high dose radiation. Open acoustic neuroma surgery is generally reserved for very large tumors that significantly compress the brainstem, an adjacent critical structure. In some cases, significant compression of the brainstem can be a life threatening situation. Fortunately, non-invasive techniques using radiosurgery can be used to stop further growth when tumors are detected before significant growth occurs. Therefore, it is helpful if these lesions are detected early. If you have questions about acoustic neuroma treatment, please contact us.
Gamma Knife Treatment
Gamma knife radiosurgery is a non-invasive procedure that uses a number of converging radiation beams that are designed to deliver a high level of radiation to a very small and precise target. The patient’s head is fixed to a stereotactic frame which is attached to the treatment table for targeting purposes. Treatment is delivered in a single session or treatment fraction.
The CyberKnife system utilizes a LINAC (linear accelerator) attached to a robotic arm that delivers several precise radiation beams to the target. Rigid head fixation is not required as in Gamma Knife. The CyberKnife also utilizes hypofractionation (i.e., treatment delivered over 2-5 consecutive days) that can be used to further protect healthy tissue from radiation damage. Both Gamma Knife and CyberKnife are performed as an outpatient treatment.