Acoustic neuroma (patient information)
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An acoustic neuroma (also known as vestibular schwannoma, acoustic neurinoma, or acoustic neurilemoma) is a benign, usually slow-growing tumor that develops from the balance and hearing nerves supplying the inner ear.
What are the symptoms of Acoustic neuroma?
As the acoustic neuroma grows, it presses against the hearing and balance nerves, usually causing unilateral (one-sided) or asymmetric hearing loss, tinnitus (ringing in the ear), and dizziness/loss of balance. As the tumor grows, it can interfere with the face sensation nerve (the trigeminal nerve), causing facial numbness. Acoustic neuromas can also press on the facial nerve (for the muscles of the face) causing facial weakness or paralysis on the side of the tumor. If the tumor becomes large, it will eventually press against nearby brain structures (such as the brain stem and the cerebellum), becoming life-threatening.
Neurofibromatosis may present with similar symptoms.
What causes Acoustic neuroma?
The tumor develops from an overproduction of Schwann cells (the cells that normally wrap around nerve fibers like onion skin to help support and insulate nerves.)
Who is at highest risk?
Acoustic neuromas are more common in adults, and rarely occur in children. 
When to seek urgent medical care?
Unilateral/asymmetric hearing loss and/or tinnitus and loss of balance/dizziness are early signs of an acoustic neuroma. Unfortunately, early detection of the tumor is sometimes difficult because the symptoms may be subtle and may not appear in the beginning stages of growth. Also, hearing loss, dizziness, and tinnitus are common symptoms of many middle and inner ear problems (the important point here is that unilateral or asymmetric symptoms are the worrisome ones). Once the symptoms appear, a thorough ear examination and hearing test (audiogram) are essential for proper diagnosis. Computerized tomography (CT) scans, enhanced with intravenous dye (contrast), and magnetic resonance imaging (MRI) are critical in the early detection of a acoustic neuroma and are helpful in determining the location and size of a tumor and in planning its microsurgical removal.
Early diagnosis of an acoustic neuroma is key to preventing its serious consequences. There are three options for managing acoustic neuroma:
- surgical removal
- radiation; and
Typically, the tumor is surgically removed (excised). The exact type of operation done depends on the size of the tumor and the level of hearing in the affected ear. If the tumor is very small, hearing may be saved and accompanying symptoms may improve. As the tumor grows larger, surgical removal is more complicated because the tumor may have damaged the nerves that control facial movement, hearing, and balance and may also have affected other nerves and structures of the brain.
The removal of tumors affecting the hearing, balance, or facial nerves can make the patient's symptoms worse because sections of these nerves may also need to be removed with the tumor.
As an alternative to conventional surgical techniques, radiosurgery (that is, radiation therapy--the "gamma knife" or LINAC) may be used to reduce the size or limit the growth of the tumor. Radiation therapy is sometimes the preferred option for elderly patients, patients in poor medical health, patients with bilateral acoustic neuroma (tumor affecting both ears), or patients whose tumor is affecting their only hearing ear. In some cases, usually elderly or medically infirm patients, it may be reasonable to "watch" the tumor for growth. Repeat MRI over time is used to carefully monitor the tumor for any growth.
Where to find medical care for Acoustic neuroma?
Prevention of Acoustic neuroma
There is no known prevention of acoustic neuroma.
What to expect (Outlook/Prognosis)?
The prognosis is positive when the acoustic neuroma is diagnosed and treated promptly. It is not uncommon to still experience tinnitis and long-term hearing loss after treatment. You might be required to undergo treatment multiple times as there is always a possibility for the tumor to grow back.
- Brain surgery can completely remove the tumor in most cases.
- Most people with small tumors will have no permanent paralysis of the face after surgery. However, about two-thirds of patients with large tumors will have some permanent facial weakness after surgery.
- Approximately one-half of patients with small tumors will still be able to hear well in the affected ear after surgery.
- There may be delayed radiation effects after radiosurgery, including nerve damage, loss of hearing, and paralysis of the face.