Otosclerosis

Otosclerosis is a primary disease of the bones of hearing and bone labyrinth capsule. Otosclerosis is a disease of bone in the middle ear especially the stirrup caused new bone formation spongiosus and around the window so it can ovalis fixation resulted in an the stirrup. (Brunner & Sudarth, 2001)

Etiology
a. The cause of otosclerosis is still not clear (idiopathic)
b. Opinions are generally inherited autosomal dominant.
c. Scientific evidence which states that measles virus infection affect otosclerosis.
d. Some argue that chronic measles infection in the bone predisposes affected patients to otosclerosis. virus material can be found in osteoblasts in sclerotic lesions.

 

Pathophysiology of otosclerosis is very complex. The primary key of the lesion otosclerosis is the presence of multifocal areas of sclerosis between the bone endokondral temporal. There are two phases of the identifiable pathological this disease are:

 
a. The initial phase otospongiotic
Histological features: composed of histiocytes, osteoblasts, osteocytes are is the most active group of cells. Osteocytes begin to get into the center of the bone around the blood vessels that causes dilation of blood vessel lumen and dilatation of the circulation. These changes can be seen as a picture of redness on the tympanic membrane. 

Schwartze sign is associated with increased vascular lesions that reached the periosteal surface. with the involvement of osteocytes are more and more, this area is rich in substance basic structure of amorphous and lack of mature collagen and result in the formation of spongy bone. The invention of this histological with haematoxylin and eosin staining known as the Blue Mantles of Manasse. 

b. The final phase of otosclerotic
Otosclerotic phase begins when the osteoclasts are slowly replaced by sclerotic bone osteoblasts and deposited in areas of soft resorption before. When this process occurs in the footplate will causes the stapes fixation on fenestra ovale so that disrupted the movement of the stapes and therefore transmission of sound to cochlear blocked. The end result is the occurrence of conductive deafness.
If it involves only the footplate otosclerosis, only slightly fixation to occur. Things like this are called biscuit footplate. The occurrence of sensorineural deafness in otosclerosis associated with possible release of toxic metabolic result of injuries neuroepitel, nearby blood vessels, a direct relationship with otosclerotic lesion to the inner ear. All this led to changes in electrolyte concentration and mechanism of the basement membrane.

Signs and Symptoms
a. Progressively decreased hearing
b. Tinnitus (ringing in the ears)
c. vertigo
d. Deafness 30-40 db (desible)

Posted in: Disease,Ear