19 The Atelectatic Ear
Henning Hildmann
Middle ear pressure is influenced by tubal function, the elasticity of the tym- panic membrane, the middle ear volume and the gas exchange in the middle ear. Disturbances of these factors may lead to middle ear atelectasis. In our clinical routine these factors are difficult to assess. We can see partial or com- plete atelectasis with the microscope. We have few indicators for disturbed tubal function and no clinically valuable tubal function test. We suspect tubal dysfunction in children when we see an adhesive otitis on one side and a mid- dle ear effusion on the other side. In this situation it might be wise to delay middle ear surgery.
Patients, especially children with cleft palates, and patients with neurologi- cal diseases and hypomobility of the orofacial muscles, have disturbances of the tubular muscles as well as patients with cranial deformities. These cases are relatively rare. In other cases we learn by our failures.
While partial atelectasis, especially in the posterior, superior part of the tympanic membrane, is a sequela of inflammation and possibly past tubal dys- function, complete atelectasis often indicates permanent tubal dysfunction and has a poor prognosis for middle ear reconstruction and hearing improve- ment. The first group can be operated on following the normal principles of tympanoplasty, whereas recurrences in the latter often fail again when reope- rated on. For these patients a hearing aid may be the better option.
Complete atelectasis indicates serious tubal dysfunction. These cases are an indication for a cartilage tympanoplasty to increase the elastic resistance of the tympanic membrane and the resistance to underpressure in the middle ear. When the mucosa of the middle ear is missing, scar contraction of the healing tissue is another explanation for the high frequency of failures in these cases. Therefore any remnants of mucosa should be respected carefully. Inser- tion of silicone does not always prevent readhesions.
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