PubMed · 5962419
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1966. [Study session for otomicrosurgery].. https://pubmed.ncbi.nlm.nih.gov/5962419/
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Although tympanic-membrane (TM) perforations are common sequelae of middle-ear disease, the hearing losses they cause have not been accurately determined, largely because additional pathological conditions occur in these ears. Our measurements of acoustic transmission before and after making controlled perforations in cadaver ears show that perforations cause frequency-dependent loss that: (1) is largest at low frequencies; (2) increases as perforation size increases; and (3) does not depend on perforation location. The dominant loss mechanism is the reduction in sound-pressure difference across the TM. Measurements of middle-ear air-space sound pressures show that transmission via direct acoustic stimulation of the oval and round windows is generally negligible. A quantitative model predicts the influence of middle-ear air-space volume on loss; with larger volumes, loss is smaller.
We report the use of a self-retaining aural speculum that provides an excellent view of the middle ear through a small endural incision. We have found this instrument of value in tympanoplasty and stapes surgery in particular.
Otitis media with effusion (OME) is a common condition that can cause deafness as well as speech and behavioural disturbance. It has long been considered to be a noninfective process resulting from Eustachian tube dysfunction; however, molecular biological techniques have implicated bacteria in the aetiology of this condition. One such organism is Alloiococcus otitidis, which has been detected in middle ear fluid of patients with OME which has not yielded micro-organisms with conventional microbiological culture methods. The exact role of this infectious agent in the pathogenesis of otitis media has yet to be elucidated.