Is Vestibular Schwannoma a Type of Cancer?

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.

There are two types of vestibular schwannomas or acoustic neuromas:

1. 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.
2. 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.

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

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

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