What you should know about acoustic neuroma before talking to your surgeon or going under knife

1. Five things Doctor will ask that you want to know.

When you visit the doctor’s office, he will ask for the following 5 issues.

  1. Your health histories
  2. Your family members’ health
  3. Examine your neurological functions
  4. Examine Examine your health status
  5. Taking details of any prior treatments (surgery, radiation and medication)and physiotherapy

2. The neurological examination will assess

  1. Your consciousness
  2. Mental status
  3. Cranial nerve functions, such as vision, eye movements, hearing, facial movements, smell and tongue movements
  4. Motor function such as limb strength, and coordination
  5. Sensory function such as response to pain sensation
  6. Reflection.
  7. Cerebellar function such as coordination of arm and body.

3. If you have any sign of hearing difficulty, he will arrange 3 types of hearing tests to diagnose acoustic neuroma.

  1. An audiogram is a test to evaluate the efficiency of binaural hearing, and is an important first step in the diagnosis of acoustic neuroma, which are the most basic audiological tests used to check sound perception, and the result is often expressed as a pure tone average (PTA).
  2. Speech discrimination (SDS) test assesses speech discrimination and the result is expressed as a speech discrimination score (SDS) socre.
  3. The third involves the auditory brainstem response(ABR) evoked potential.

Given that information is passed to the brain through a pathway from the ear, these line of testings could be hampered by abnormalities of the auditory nerve functions.

4. If abnormalities of the 3 hearing tests are detected, magnetic resonance imaging (MRI) or computed tomography (CT) scanning are likely to performed.

CT scanning is intended to detect any abnormalities within the temporal bone, particularly within the IAC. For some brain tumors, in order to provide the most sensitive images, an injection of contrast medium is required.

MRI is a more advanced computer technology that produces finer images of the brain and nerves. The signal produced by MRI scanning allows subtle changes in the brain and nerves to be detected even at very early stages.

For the diagnosis of acoustic neuroma, the accuracy of MRI can be increased by using a contrast agent called gadolinium. MRI is a relatively simple test without X-ray radiation that causes no side effects or pain.


5. What is acoustic neuroma?

The acoustic nerve is also known as the auditory nerve or the vestibulocochlear nerve, and is actually a triad bundle of nerves that control hearing and balance. This bundle consists of one cochlear nerve that is responsible for hearing, and two branches of the vestibular nerve responsible for the sense of balance.

An acoustic neuroma arises from the cells surrounding one of the two branches of the vestibular nerve located in the deepest part of the internal auditory canal (IAC), which is the bony hole through which the nerve enters the inner ear.

The cells covering the vestibular nerve are called Schwann cells, and so acoustic neuroma is also known as vestibular schwannoma.

Within the IAC, the facial nerve is located immediately next to the vestibulocochlear nerve. As an acoustic neuroma grows, it exerts great pressure on other nerves, such as the cochlear nerve and the facial nerve.

The cochlear nerve is very fragile and has no capacity to regenerate, so once hearing starts to decline it will never be restored.

As the acoustic neuroma continues to grow, it can extend out of the IAC, and start to put pressure on the brainstem, which is the essential center of our consciousness, breathing, and heart rhythm.

In most patients, the main symptom of acoustic neuroma is unilateral hearing loss, which is often accompanied by tinnitus.

This hearing loss is generally mild and seems to progress slowly. These subtle initial symptoms can thus be confused with changes caused by aging, and great care has to be taken in diagnosis.

As the tumor grows, the patient can develop a sense of unsteadiness and problems with balance. Because of the proximity to the vestibulocochlear nerve and facial nerve, facial nerve paralysis can develop as the tumor grows. Larger tumors tend to cause abnormal facial sensations due to constant pressure on the trigeminal nerve.

More severe brainstem compression can follow, leading to hydrocephalus from obstruction of the flow of cerebrospinal fluid (CSF) from the fourth ventricle. If the hydrocephalus continues for an extended period of time, it can cause a decline in vision and overpowering headaches.

Very strong headaches, feelings of agitation, and disturbed consciousness are all potential indicators of increased intracranial pressure, and this critical condition must be addressed urgently.