د.حسين جاسم                       
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.