Vestibular schwannoma or acoustic neuroma is a benign, slow-growing brain tumor that starts in the vestibulocochlear nerve
Vestibular schwannoma or acoustic neuroma is a benign, slow-growing brain tumor that starts in the vestibulocochlear nerve, which is responsible for hearing and balance. In most cases, vestibular schwannoma grows very slowly but can cause symptoms due to compression of surrounding structures and can be locally invasive.
These tumors typically affect men and women equally in their 40s or 50s and are much less common in children. If not treated early, the tumor can increase in size, compress surrounding structures, and cause dangerous buildup of fluid in the brain, which can be life-threatening.
How does a vestibular schwannoma affect the body?
Vestibular schwannomas are rare and occur in about 1 out of every 100,000 people. The neuromas are linked to the mutation in a tumor-suppressor gene on chromosome 22 that controls the growth of Schwann cells—an insulating membrane covering the vestibulocochlear nerve. These tumors originate mostly from the vestibular division of the eighth nerve but can affect both hearing and balance functions as they grow.
More than 90% of these tumors affect the hearing nerve in one ear and result in unilateral hearing loss. For some people, it can affect both the ears and lead to bilateral hearing loss.
These noncancerous tumors can also press on the nerves that control facial movement, sensation, and expression, as well as on brain structures that control the flow of spinal fluid out of the brain.
What are the different types of vestibular schwannomas?
There are two types of vestibular schwannomas or acoustic neuromas:
- Sporadic or unilateral acoustic neuroma: Most common type of acoustic neuroma that occurs due to sudden, nonhereditary mutations or due to nerve damage caused by environmental factors such as past radiation to the head and neck. It may develop at any age, more commonly affecting people ages 30-60.
- Genetic or bilateral acoustic neuroma: Affects both sides and is associated with a genetic disorder called neurofibromatosis 2 (NF2). Patients often have tumors throughout the body, and their treatment differs from the treatment for unilateral tumors.
What are the signs and symptoms of vestibular schwannomas?
Signs and symptoms of vestibular schwannomas are often easy to miss because they develop gradually over years.
The most common symptom is hearing loss on the side of the tumor. Other signs and symptoms include:
- Tinnitus (ringing) in the affected ear
- Unsteadiness or loss of balance
- Vertigo (dizziness)
- Facial numbness, twitching and weakness
- Headache and pressure
- Swallowing problems
- Change in taste and tear production
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How is vestibular schwannoma diagnosed?
Because symptoms resemble other middle ear or inner ear problems, the condition is often difficult to diagnose. Diagnosis starts first with an ear examination, followed by a hearing test and imaging tests. Diagnosis is made based on:
- MRI scans with contrast dye
- Audiometry (hearing test)
- Auditory brainstem response test
- Increased pure tone average
- Increased speech reception threshold
- Decreased speech discrimination
How is vestibular schwannoma treated?
Treatment may vary depending on:
- Size and growth of the tumor
- Severity of symptoms
- Overall health of the patient
Treatment may include:
- Observation
- Surgery to remove the tumor
- Radiosurgery (gamma knife), which uses focused radiation to reduce the size or stunt the growth of the tumor
- Supportive therapy such as cochlear implant surgery to treat hearing loss