2 Atelectasis & adhesive otitis Kayvan Aghazadeh M.DAssistant prof. of otolaryngologyTehran university of medical siencesAmir Alam hospital
3 Middle ear atelectasis is thought to result mainly from long-standing eustachian tube dysfunction. One of the main functions of the eustachian tube is ventilation of the middle ear and mastoid
4 Opening of the eustachian tube allows exchanging of gases and equalization between the environment and middle ear.The middle ear gases also are exchanged with the middle ear mucosa.
5 Bilateral diffusion between the middle ear cavity and the blood may be an important factor in middle ear atelectasis because:the gas composition of the middle ear basically resembles that of venous blood.
6 If the atelectasis develops, the tympanic membrane becomes retracted onto the promontory and the ossicles of the middle ear.
8 In atelectatic ears, the middle ear space is partially or completely obliterated, but the tympanic membrane is not adherent to the medial wall of the middle ear,and the mucosal lining of the middle ear is intact
14 Not all patients with chronic OME develop atelectasis; in most patients with OME, retraction of the tympanic membrane is limited.In patients with bilateral OME, 1.5% of untreated ears and 2% of ears treated with tubes developed severe atelectasis.
15 It may be that repeated bouts of AOM lead to weakening and thinning of the membrane, which allows atelectasis
16 Sad and Berco showed destruction of the collagen-containing fibrous layer of the tympanic membrane in some ears with recurrent infection.Collagen destruction within the tympanic membrane may lead to another complication of OME—tympanosclerosis
18 . Sad and Berco and Tos and Poulsen described four stages of tympanic membrane retraction: stage I, retracted tympanic membrane;stage II, retraction with contact onto the incus;stage III, middle ear atelectasis; andstage IV, adhesive otitis media
22 Graham and Knight reported three cases in which atelectatic tympanic membranes were restored to their normal positionby administration of nitrous oxide during anesthesia and insertion of a ventilating tube.
23 Atelectasis and adhesive otitis media usually coexist with OME, although OME may resolve in these ears, allowing aeration of the attic and mastoid, but leaving a collapsed middle ear.
24 In extreme cases, when hearing loss or ossicular erosion occurs, a myringoplasty for the reinforcement of atelectatic tympanic membrane may be indicated.
25 Cholesteatomas may originate from deep retraction pockets in which desquamated keratin debris would not be cleared into the ear canal