Acoustic neuroma is a benign tumor that affects the nerves running from the inner ear to the brain. The nerves that are responsible for hearing and balance are prevented from functioning properly, leading to hearing loss and tinnitus (ringing in the ears).
In the later stages, acoustic neuroma may affect the nerves of the cerebellum and brainstem, and it can increase pressure in the brain, which can be life-threatening.
Acoustic neuroma is also known as acoustic neurinoma, vestibular schwannoma, and auditory tumor.
A layer of cells, called Schwann cells, covers nearly all healthy nerves. Schwann cells provide insulation and support for nerve impulses; if they begin to multiply too quickly, acoustic neuroma occurs. Between 2,000 and 3,000 new cases are diagnosed each year in the United States, or around 10 per million people.
Fast facts on acoustic neuroma
Acoustic neuroma is a benign tumor that affects the inner ear.
Common symptoms include hearing loss and tinnitus.
There are many treatment options, including surgery.
Treatment for acoustic neuroma depends on several factors, including the patient’s age and general health, and the location and size of the tumor. In some cases, watchful waiting is recommended, and if the tumor is small or slow-growing, no further action may be taken.
Treatment options include:
Stereotactic radiosurgery – the doctor can deliver radiation precisely to the tumor without having to cut into the patient. A lightweight head frame is attached to the patient’s scalp, which has been numbed. The tumor is precisely located with the help of imaging scans – the scans help determine where exactly to apply the radiation beams. The patient may experience neck stiffness and nausea.
Microsurgical removal – this involves removing a tumor through an incision in the skull. It is carried out under general anesthesia. In about 95 percent of cases, surgery controls the tumor. If the tumor is very small and nerve damage is minimal, hearing may be saved and symptoms improve.
Rarely bits of the tumor may be left behind if the surgeon believes there may be a risk of nerve damage. If this is the case, radiotherapy may be used to finish them off.
Radiation therapy – radiotherapy may be used instead of conventional surgery, to reduce the size or limit the growth of the tumor. It is sometimes used after surgery, to remove any remaining traces of the tumor. The radiation is carefully targeted to minimize damage to healthy tissue surrounding the tumor.
Radiosurgery – this type of treatment delivers radiation directly to the tumor. Imaging scans are used to locate the tumor. A frame is attached to the patient’s scalp to achieve this treatment, which can cause stiffness or nausea.
Monitoring and MRI – as many acoustic neuromas do not grow, continuous monitoring may mean treatment is not required. In this case, MRI (magnetic resonance imaging) scans can determine the growth of the tumor.
After surgery, a doctor will monitor the patient’s recovery and check for recurrence of symptoms.
Potential for hearing loss
Some patients have a degree of permanent hearing loss after surgery. This usually depends on the size of the tumor. The risk is higher if a tumor is over 1.5 centimeters across.
If a patient has neurofibromatosis type 2, and if tumors have developed on both acoustic nerves, the patient may be unable to hear with either ear after surgery.
In this case, doctors prefer to delay surgery for as long as possible.