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An acoustic neuroma or vestibular
schwannoma, is a
benign (non-cancerous) tumor that arises on the (8
th cranial) nerve. This is the nerve that affects your hearing and balance.
Acoustic neuromas usually grow slowly over a period of years. They expand
in size at their site of origin and when large can displace normal brain
tissue. The brain is not invaded by the tumor, but the tumor pushes the
brain as it enlarges.
The causes of an acoustic neuroma are unknown however research has shown
that there are people with certain risk factors who are more likely to
develop this condition over those outside of the risk factors. These risk
Family history of
Early symptoms of acoustic neuromas include partial hearing loss or complete
hearing loss in one ear (this is usually subtle and worsens over time).
More than 80% of patients have reported ringing in the ears (tinnitus) described as high-pitched ringing, sometimes a machinery-like roaring
or hissing sound. Since the balance portion of the nerve is where the
tumor arises, unsteadiness and a disturbed sense of balance, and possibly
vertigo with associated nausea and vomiting may occur during the growth
of the tumor. Larger tumors can press on the
trigeminal nerve, causing facial numbness and tingling - constantly or intermittently. Tumor
related increase of intracranial pressure may cause headaches, clumsy
gait and mental confusion. This can be a life-threatening complication
requiring urgent treatment.
Even though the facial nerve (the nerve that moves the face) may be compressed
by the tumor, it is unusual for patients to experience weakness or paralysis
of the face from acoustic neuromas - although this may occasionally occur.
Diagnosis of an acoustic neuroma begins with a full medical history of
the patient to rule out any other conditions. After medical history is
collected a physical examination will be done which may include an audiogram
to evaluate the hearing in both ears. A brainstem auditory evoked response
test may also be performed. This hearing test measures your brain's
response to clicking sounds in your ear. This test helps determine whether
the eighth cranial nerve is working and if your hearing and brainstem
are functioning properly. If an acoustic neuroma is suspected, an MRI
or CT scan will be performed to confirm the presence of a neuroma.
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