A Family Doctor's Tale - ACOUSTIC NEUROMA

DOC I HAVE ACOUSTIC NEUROMA

Acoustic neuroma is a rare benign tumor rarely seen outside the Ear Nose Throat Department.

Although it is not cancerous, it can become bigger and impinges on the acoustic or hearing nerve causing deafness.

It can also affect the 5th, 7th and sometimes the 9th and 10th cranial nerve.

It can also increase the intracranial pressure in the brain.

Treatment is usually by microsurgery or radiation (gammaknife ) to remove the tumor.


Acoustic neuroma is a neurofibroma of the eight nerve.

1.Both sexes are equally affected.

2.Acoustic neuroma occurs more in the 50- 60 age group.

3.It forms 5-10% of the intracranial tumors in adults.

There are 2 different types of Acoustic neuroma:


1.Neurofibroma I -
a. Unilateral acoustic neuroma usually
Bilateral acoustic neuromas are not common.

b. occurs in adult life,

c. the tumor involve the 8th nerve,

d. can involve any other cranial nerve or the spinal root.

e.Incidence is usually 90-95%

2.Neurofibroma II -
a. bilateral acoustic neuromas are common

b. occurs before the age of 21.

c. affects the entire nerve

d. autosomal dominant inheritance.

e. Incidence is about 5 to 10%.



Acoustic neuroma in the adult begins in the Schwann's cells of the vestibular portion of the 8th nerve inside the internal auditory canal.

The tumor grows slowly and can extend into the posterior fossa to occupy the space between the cerebellum and the pons.

Because of its location, it can also compress the 5th, 7th, and less often, the 9th and 10th cranial nerves.

If it grows larger, it may also compress the pons and lateral medulla of the brain, causing blockage of the cerebrospinal fluid and increased intracranial pressure.



Symptoms:
1.unilateral hearing loss

2.tinnitus with unilateral high-pitched ringing sound

3.loss of sense of balance

4.vertigo

5.nausea and vomiting

6.altered gait

7.pressure in the ear

8.rarely headache and altered consciousness.

Signs:

1.unilateral facial weakness.

2.sensory impairment of the nerve

3.impairment of glandular secretions

4.loss of taste

5.loss of sensation in one side of the face and mouth

6.rarely altered gag or swallowing reflexes.

Diagnosis of Acoustic neuroma is made by:

1.Contrast-enhanced CT will detect almost all acoustic neuromas that are greater than 2.0 cm in diameter

2.MRI with gadolinium enhancement may show even smaller tumors

3.Audiology and vestibular tests are done to check for Nerve versus conduction hearing loss.



Treatment of acoustic neuroma is usually by surgery and radiotherapy.

Conservative treatment

In some cases because the neuroma grow so slowly, the tumor is monitored by annual MRI to see its growth.

This method is common among patients over 70 years old.

In rare cases, acoustical neuroma have been known to disappear spontaneously.

Acoustic neuroma may result in gradual hearing loss and tinnitus.

Surgery


Surgical removal of acoustic neuroma usually involves microsurgery to remove the tumor.

The superior and inferior vestibular nerves are removed at surgery.

This effectively restores balance in the patient.

Radiation treatment


Radiotherapy using gamma knife radiosurgery or fractionated stereotactic radiotherapy does not remove the tumor but is able to slow or stop its growth.



Prognosis is good in all early diagnosis and small tumors.

Large tumors may give rise to residual neurological damage even after removal.