Tympanosclerosis

Diagnosis

Tympanosclerosis is thought to be a complication of otitis media in which acellular hyalin and calcified deposits accumulate within the tympanic
membrane and the submucosa middle ear. In most patients, these plaques are clinically insignificant and cause little or no hearing impairment.
Tympanosclerotic plaques within the tympanic membrane appear as a semicircular crescent or horseshoe-shaped white plaque within the tympanic
membrane.

Pathogenesis

Tympanosclerosis is a consequence of resolved otitis media or trauma. Hussl and Mueller70 found tympanosclerosis to be a frequent sequela of
chronic OME, and they found it in 19.7% of drumheads 6 to 8 years after the insertion of ventilating tubes for OME. They also noted that middle ear
tympanosclerosis often was seen after recurrent bouts of AOM. Tos and Stangerup146 found a significant increase in tympanosclerosis in ears in
which grommets were placed (59%) compared with the contralateral ears, in which only myringotomy was performed (13%). Daly44 reported the
weighted average incidence of tympanosclerosis is 10% in children aged 4 to 15 years, with an average follow-up period of 4 years. The incidence
of tympanosclerosis in chronic otitis media has been reported from 9% to 38%. Kinney80 found that 20% of 1495 patients undergoing surgery for
chronic otitis media or its sequelae had tympanosclerosis, and Magat and others91 found 23.6% of 1274 patients treated with tympanostomy tube had
tympanosclerosis.

Tympanosclerosis appears histologically as a hyalinization of the subepithelial connective tissue of the tympanic membrane and middle ear; in most
instances, calcification is present. Osteoneogenesis also can occur within these lesions. The bone deposition and ossicular fixation occur most
frequently in the attic associated with the heads of the malleus and incus. When plaques occur within the tympanic membrane, they are limited to the
lamina propria. Hussl and Lim69 found these plaques to be a degenerative process resulting in calcification in connective tissue of the middle ear.
They hypothesized that OME or AOM led to a destructive process within connective tissue, which led to degeneration of collagen and subsequently
dystrophic calcification and tympanosclerosis. The degeneration of collagen may be a direct result of inflammation or infection within the middle ear
(e.g., by bacterial proteinases and collagenases). Wielinga and others155 showed that eustachian tube obstruction alone, without infection, caused
tympanosclerosis in rats; they hypothesized that deformation alone was sufficient to cause the plaques to form. Another possible cause of
tympanosclerosis is an autoimmune process occurring within the tympanic membrane. Schiff and others133 prepared antisera to guinea pig lamina
propria and passively immunized guinea pigs. When the tympanic membranes of these animals were traumatized, tympanosclerotic plaques
developed. Chole and Henry36 found that LP/J inbred mice spontaneously developed middle ear lesions that resembled tympanosclerosis and may be
immunologically mediated.19 Hussl and Lim69 proposed two possible mechanisms for the formation of tympanosclerotic plaques, beginning with
collagen degeneration.

Management

Tympanosclerosis within the middle ear  is histologically similar to that occurring within the tympanic membrane, but it often leads to
conductive hearing loss caused by ossicular fixation. Although some authors have stated that tympanosclerosis tends to recur after surgical removal,
others have reported stable hearing results in these patients. Smyth and others141 reported excellent hearing results in 79% of tympanosclerotic ears
in which ossicular reconstruction (stapedectomy and total ossicular reconstruction) was performed in two stages, although Gormley58 found that only
7% of his cases had an air–bone gap of less than 21 dB on long-term follow-up evaluation, questioning the advisability of stapedectomy in ears with
tympanosclerosis. It should be noted that in the earlier series140 in which one-stage procedures were performed, 21% of 57 cases result in cochlear
losses. Tympanoplasty and ossicular reconstruction can be performed in ears with tympanosclerosis, but the risks of cochlear damage appear to be
greater than in other middle ear diseases because of the extensive dissection that is required in tympanosclerotic ears and the coexistence of
labyrinthine erosion.

 

 
 
 

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