Vestibular Schwannoma (Acoustic Neuroma)
A Vestibular schwannoma, previously known as an acoustic neuroma, is one of the most common forms of brain tumor. It usually occurs on one side of the brain and is often detected in the third to sixth decade of life. The tumor is comprised of cells, called Schwann cells, and is therefore often referred to as a "Schwannoma." The tumor is relatively slow growing, and may go unnoticed until symptoms occur. The symptoms of acoustic neuroma include:
- Unilateral hearing loss
Hearing loss is caused by the tumor pressing on the eighth cranial nerve, which controls hearing. This is the most common symptom of acoustic neuroma. The person may notice a decrease in the hearing acuity in one ear, while the other ear is unchanged. Often, the person may notice listening on the telephone becomes more difficult with one ear. High pitch voices or music may be difficult to hear. The hearing loss may be slow and go unnoticed in the beginning, and may progress to almost complete hearing loss in one ear.
- Ringing in the ear, tinnitus
The person may notice a high pitch ringing in the affected ear. The ringing is constant, and may further affect the hearing loss.
- Dizziness
The person may have a sensation of dizziness or lightheadedness. Often, balance or walking is affected due to the feeling of dizziness.
- Facial pain, and facial weakness
The pain and weakness occur later, as the tumor enlarges, and presses on the cranial nerves. They are usually noticed on one side only (the same side as the hearing loss), and are slowly progressive.
Diagnostic tests
If your health care provider suspects you may have a vestibular schwannoma, you will have a physical and neurologic examination and one or more of the following tests may be performed:
- Audiogram
This hearing test is often one of the first tests performed to determine the type and extent of hearing loss in the affected ear. The test is performed in a sound-proof room by an audiologist.
- CT scan
This is a special x-ray image of the brain to determine the size of the ventricles, if there is a tumor, and the size and location of the tumor. The test is performed by having the patient lie on a flat x-ray table which slides into a round, open scanner. The x-ray images are taken as the patient is lying still on the x-ray table. Often, this test involves the injection of a contrast dye to obtain better images of the brain structures (be sure to tell your health care provider if you are allergic to dye or have ever had a reaction to dye).
- MRI (magnetic resonence image)
This is a special non-x-ray image of the brain to determine the size of the ventricles, if there is a tumor, and the size and location of the tumor. No x-rays are used in this test. The test is performed by having the patient lie on a flat imaging table, which slides into an enclosed tube. It is important to lie very still while in the scanner, as the pictures are very sensitive to any movement. You will hear a machine-like sound, as the pictures are taken. The space inside the tube is quite snug, therefore, be sure to tell your health care provider if you are claustrophobic, or uncomfortable in very tight places. Because this test is performed with a special high-power magnet, it may not be performed on anyone with a metal implant (ie. artificial limbs, artificial joints, aneurysm clips, shrapnel, or metal heart valves). If you are unsure of any metal in your body, please tell the MRI technician before the test begins.
- Angiogram
In a few cases, your doctor may recommend an angiogram. This test is performed by a radiologist in a special x-ray room (called the Angiogram suite). A catheter is inserted through the large artery in the groin, and contrast dye in injected. X-ray images are then taken as the dye travels through the vessels of the brain. The test is done to determine the blood supply to the tumor, as well as the blood supply to the surrounding tissue. The test takes approximately 1-2 hours, and you must lie flat in bed for 6-8 hours after the test to prevent bleeding from the groin injection site. You may be given a mild anesthetic prior to the test, but you will be awake during the test so you can talk to the radiologist. Some people report a feeling of heat or flushing as the dye is injected.
Treatment
Often, the best treatment for a diagnosed vestibular schwannoma is surgical removal. The patient is taken to the operating room, and under general anesthesia, the tumor is removed. The neurosurgeon performing the operation will discuss the procedure, risks and benefits in more detail.
Questions you may want to ask
- How long will the procedure take?
- Where will I be after surgery, intensive care, step-down, etc.?
- When will I hear about the results of the tumor tissue (is it malignant or benign)?
- What are the complications from this type of surgery?
- Is the tumor likely to recur?
- Will my hearing loss be permanent?
- What is the recovery phase like?
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