Acoustic Neuroma (Tumour of the 8th cranial nerve)

Anatomy and Physiology of the Ear Click here

The 8th cranial nerve is the nerve that serves the hearing and balance functions of the body. A tumour of the balance portion of this nerve (Acoustic neuroma) is a cause of a balance disorder.

Causes of a Tumour of the nerve of balance

An acoustic neuroma arises from the fibrous sheath of the nerve of balance (vestibular nerve) within the internal auditory canal.

Symptoms

The initial symptom of an acoustic neuroma is tinnitus (noise in the ear). Deafness appears later and so does vertigo. Occasionally the presentation is by a sudden deafness. The vertigo is usually a constant sense of imbalance. As the tumour grows in size, it presses on adjoining areas – cerebellum and brain stem. Pressure on the Cerebellar causes increasing imbalance, increasing tinnitus and increasing heraing loss. Pressure on the Brainstem causes various neurological problems.

Confirmation of the diagnosis

Pure tone Audiometry, Impedance bridge studies and vestibular (balance) tests. Electronystagmography is the gold standard by which the function of the balance organ is measured. An M.R.I.Scan of the brain will show a suspicious shadow occupying the internal audiitory canal and cerebello pontine angle.

How is it treated?

Early diagnosis is extremely important as the treatment is surgical removal of the tumour. Every case of noise in th ear should be properly investigated by Pure tone Audiometry, Impedance bridge studies and vestibular (balance) tests. Electronystagmography. The sooner this is done, the better, since this the tumour grows in a closed space, next to vital brain stem structures responsible for cardiac function and respiration and the larger it is, the more difficult it is to remove. There is no place for medical treatment.

Vestibular Rehabil Exercises Click here

Precautions during vertgo attacks Click here

Results of Audio – Vestibular investigations of a patient with Right Acoustic Neuroma

Pure Tone Audiogram showing a moderately severe to severe sensori neural hearing loss in the Right ear

Electro Nystagmography recordings of a patient with a Right Acoustic Neuroma

Recordings of the Caloric test

Right ear warm stimulus

Right ear cold stimulus

Left ear warm stimulus

Left ear cold stimulus

Recordings of right and left ear caloric responses for frequency calulations