diseases of the inner ear

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L.5 Diseases of the inner ear

Congenital: include aplasia & hypoplasia & is usually associated with other

congenital anomalies.

Acquired:

A. Traumatic diseases:
1. .Fractures of the temporal bone(transverse):
It occurs after severe head injury & the fracture line affects the inner
ear causing (sensorineural hearing loss, vertigo, nystagmus & facial nerve
palsy).
Investigation: CT scans.
Treatment:
a. .Vestibular sedatives.
b. . Surgical repair of the facial nerve.
c. .Auditory rehabilitation if necessary.
2. .Aquistic trauma:
This means loss of hearing due to exposure to a loud noise or working
in a noisy environment.
3. .labyrinthine membrane rupture:
Defined as leakage of perilymph through a fistula in the labyrinthine
windows (oval window, round window) so it’s a perilymph fistula.
Etiology:
- -Sudden rise in the intracranial pressure due to straining or lifting heavy
weight.
- -Sudden increase of the middle ear pressure as a result of sneezing or nose
blowing.
Clinical features:
- -Sudden sensorineural deafness & tinnitus.
- -Sudden vertigo.
Treatment:
Conservative: bed rest , head up position & avoidance of straining.
Failure: surgical repair of the fistula by putting a graft.


B.Inflammatory disease of the inner ear:
As labyrinthitis which usually occur as a complication of CSOM.
C. Hematological diseases:
As in leukemia (AML, ALL) which may cause hemorrhage in the inner ear, this
condition may occur also with vasculitis.
D. Toxic effects:
It’s the most important disease affecting the inner ear usually due
to drug use especially aminoglycosides in particular streptomycin, kanamycine &
gentamicin, for this reason these drugs reserved for severe infections.
E. In elderly: Senile deafness is very common & is called
presbyacusis; it’s a degenerative disease of the cochlea with destruction of
the inner ear.
F. Others:
Menieres disease
It’s a disruption of the membranous labyrinth due to increase
volume of the endolymph caused by any block in the circulation of the endolymph
leading to increase pressure of the endolymph & distension of the membranous
labyrinth.
Etiology:
1. Unknown.
2. Decrease in the absorption of the endolymph by the endolymphatic
sac.
3. Increase in the production of the endolymph due to changes in the
capillary permeability.
Clinical features:
- A clinical triad is the usual presentation:
vertigo, hearing loss, & tinnitus. The attack lasts for several
minutes to several hours.
- Usually associated with nausea & vomiting.
- Hearing loss & tinnitus are reversible at the beginning, but
becomes more permanent & progressive.
- Sensorineural hearing loss.
- Normal TM.
Investigation:
1. .Pure tone audiometry: This shows sensorineural hearing loss.
2. .Caloric test (vestibulometry):
This test is used to test the efficacy of the semicircular canals of
the inner ear, which are responsible for rotational movement during position
changes, while the utricle & saccule are responsible for linear movement.
The test is applied by asking the patient to sleep on a couch & we
prepare water at a temperature of 30-44 C (plus, minus 7 C degrees that of the
body temperature) in addition we use a kidney dish to collect the water in after
irrigation.
The irrigation started at each ear separately (there must be no
inflammation, noTM perforation & the patient is not in an acute attack). The EAC
is filled & with continuous irrigation (irrigation time is 40 seconds & time
between irrigations is 5 minutes) the response is developed as nystagmus that
persist for (1.5-2 minutes).
The affected semicircular canal show either decreased response in
case of incomplete damage or no responses at all in case of complete damage of
the semicircular canal.
The test is done in each ear separately & the response is bilateral
in the eyes.
Treatment:
Medical:
1. .Vestibular sedatives e.g./ cinnarizine (stugeron) & largectil
(chlorpromazine) ½ ampule intramuscular during the attack.
2. .Labyrinthine vaso-regulator e.g./ betahistine (betaserc).
3. .Labyrinthine decompressant e.g. / lazix & salt restriction.
Surgical:
Failure of the above measures to control the condition will lead to the use
of surgery as follows:
1. .Decompression of the endolymphatic sac.
2. .Selective section of the vestibular nerve.
3. .Labyrinthectomy.
The choice between these operations depend on the degree of the hearing loss, if
the hearing is serviceable (there is a good residual hearing) decompression & /
or selective section of the vestibular nerve is used, but if there is no
residual hearing is present then Labyrinthectomy is used.