Acoustic Neuroma

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There are 12 cranial nerves in the nervous system of humans. One of them is the vestibulocochlear nerve, the eighth cranial nerve of nervous system. This nerve has two parts; vestibular and cochlear. This nerve lies right under the brain and connects the ear with the brain. Tumor arising from this nerve is called acoustic neuroma. It is very uncommon.

Contents

DEFINITION

NATURE AND TYPE OF TUMOR

SCHWANN CELLS

SYNONYMS

EPIDEMIOLOGY

CAUSES OR ASSOCIATED CONDITIONS

CLINICAL MANIFESTATIONS

DIAGNOSIS

TREATMENT


DEFINITION

Acoustic neuroma is a rare tumor of vestibulocochlear nerve, primarily involving the vestibular part of the nerve and arising from the Schwann cells.

NATURE AND TYPE OF TUMOR

Acoustic neuroma is a benign intracranial neoplasm that never metastasizes to distant organs and has a very good prognosis.

SCHWANN CELLS

Schwann cells are the specialized cells of the peripheral nervous system responsible for the synthesis of myelin sheath around the nerves.

What are the other names of acoustic neuroma?

Acoustic neuroma is also named as;

u Vestibular schwannoma

u Cerebellopontine angle tumor

u Tumor - acoustic

u Angle tumor

EPIDEMIOLOGY

Several studies have shown that almost three thousand cases of acoustic neuroma are being diagnosed in the US every year. The prevalence of this disease is not much high with 1/100000. Most of the patients are in their sixties or seventies. Males and females are affected equally.

CAUSES OR ASSOCIATED CONDITIONS

Most of the times the cause of acoustic neuroma is unknown (idiopathic) However, like all other tumors acoustic neuroma may have a strong genetic cause linked to it. Here is the hereditary condition or syndrome in which acoustic neuroma can occur as one of the manifestations;

u Neurofibromatosis type 1 (NF-1)

u Neurofibromatosis type 2 (NF-2)

Both are very rare genetic disorders in which unilateral or bilateral acoustic neuroma can occur. It may also be associated with mobile phone use (not well recognized).

CLINICAL MANIFESTATIONS

The signs and symptoms of this disorder are;

u Hearing loss - it is the very first and the most common presentation of this disease. As the nerve is involved so the hearing loss of deafness will of sensorineural type. It develops slowly and is unilateral. Tuning fork tests help distinguishing between nerve deafness and conduction deafness.

u Tinnitus - in simple words it is known as ringing of ears. Any type of voice or sound may be heard in the ear when no external sounds are present in the surroundings.

u Vertigo - it is a condition characterized by feeling of movement when one is not moving. It is also a characteristic symptom of acoustic neuroma.

u Nausea and vomiting - usually accompanied by vertigo

u Difficulty in understanding speech

u Dizziness

u Numbness or may be pain in face or one ear

u Headache

u Altered gait and balance

How to diagnose acoustic neuroma?

Acoustic neuroma is diagnosed on the basis of following radiological investigations;

u Contrast enhanced computed tomography (CT scan) - it can detect the tumors greater than 2 cm in size

u Tumors smaller than 2 cm are imaged with the help or magnetic resonance imaging (MRI) or gadolinium enhanced imaging

u Moreover, tuning fork tests can differentiate between nerve deafness and conductive deafness.

How to treat acoustic neuroma?

Here are the different lines of treatment used for acoustic neuroma;

u Conservative or medical - patients are observed and monitored with the help of MRI. Usually they are benign and do not grow at all in three to five years

u Surgical removal - tumors growing fast and causing trouble are removed surgically

u Radiotherapy

SUGGESTED READING

http://en.wikipedia.org/wiki/Vestibular_schwannoma

http://www.aefu.ch/typo3/fileadmin/user_upload/aefu-data/b_documents/themen/elektrosmog/internationale_Forschung/loehn_acoustic_neuroma.pdf

http://www.patient.co.uk/health/Acoustic-Neuroma.htm

SUGGESTED WATCHING

http://www.youtube.com/watch?v=z92B-fiUbnE

About the Author

Dr Ahmad's picture
Author: Dr Ahmad

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