Additional evidence is presented to support the hypothesis that both acute purulent otitis media (POM) and chronic suppurative otitis media (COM) can cause high frequency sensorineural hearing loss. In selected patients and in animals (chinchillas) in a pilot study using electrophysiological methods, both temporary threshold shifts and permanent threshold shifts of basal cochlear turn involvement were demonstrated in POM. Data of cochlear involvement in 475 ears with bilateral COM, 607 ears with unilateral COM, and 607 ears serving as controls were obtained from six centers in five countries. In group 1 (15 dB or greater), 43% of ears with unilateral COM and 42% of ears with bilateral COM showed losses, for a combined odds ratio eight times that in controls. In group 2 (30 dB or greater), 16% of ears with unilateral COM and 17% of ears with bilateral COM demonstrated, respectively, seven and ten times that in controls. These statistically significant findings influence clinical considerations.

No abstract

In spite of the wealth of information on the clinical, histologic, and pathologic aspects of tympanosclerosis, the pathogenesis of tympanosclerosis is still unclear. In an attempt to understand the pathogenesis, 319 human temporal bones from 196 individuals with otitis media were studied. The extent and nature of tympanosclerosis and the characteristics of the otitis media associated with it were studied. Forty-five temporal bones from 35 individuals with otitis media were found to have tympanosclerosis, giving an incidence of 14.1%. It was seen most commonly in individuals over 40 years of age (86.7%). The male-to-female ratio was 1.6:1. The most common site of occurrence was the tympanic membrane (88.9%). Tympanosclerosis was seen more often in the anterior and posterior inferior quadrants of the tympanic membrane and that, too, in a central position. Tympanosclerosis was seen more commonly in temporal bones with irreversible inflammatory changes, and in this group, late plaques were more commonly seen than early or intermediate plaques. Audiometric charts failed to show any direct relationship between extent of tympanosclerosis and the severity of hearing loss. The only audiometric finding of any consequence was a mixed hearing loss in the presence of middle ear tympanosclerosis.

\s=b\The effects of endotoxin, exotoxin, and otitis media on the permeability of the round window membrane (RWM) in chinchillas was investigated by detecting tetraethylammonium chloride, applied to the RWM, using a potassium-selective microelectrode in the scala tympani. The RWM, 48 hours following the application of endotoxin or exotoxin, became significantly more permeable to tetraethylammonium chloride than the normal RWM. Two weeks after the obstruction of the eustachian tube, the permeability of the RWM was decreased. These results suggest that bacterial toxins and the consequential migration of chemical inflammatory mediators act as promotive factors of RWM permeability, and that a pathologic thickness of the RWM and the presence of effusion induced by the obstruction of the eustachian tube acts as an inhibitory factor. In the clinical role of RWM permeability in human otitis media, these two factors must be taken into consideration. (Arch Otolaryngol Head Neck Surg 1988;114:895-897) Sensori neural hearing loss clinically observed in otitis media is thought to result from inflammatory and immunologie effects of the middle ear, and/or the secondary effects of antibiotics concomitantly applied to the middle ear cavity.13 Many animal studies have documented the perme¬ ability of the round window mem¬ brane (RWM), in which several sub¬ stances of different molecular size were applied to the RWM, and bio¬ chemical, histopathologic, and elec¬ trophysiologic investigations of the cochlea were performed.413 These findings indicate that the RWM can be one of the critical factors determin¬ ing the influence of bacterial toxins and chemical mediators in otitis media and antibiotics administered for otitis media on the cochlear func¬ tion. However, studies of the perme¬ ability of the RWM under various pathologic conditions are limited, as sensitive methods to measure them have not as yet been developed. Recently, a direct observation of the inner ear fluid flow was made by measuring the activity of tetramethylammonium or tetraethylammonium chloride (TEA) ions with potassium (K+)-selective microelectrodes.1415 The principle of this technique is to detect the spread of these substances using the high detectability of K+ microelec¬ trodes against them.Our animal experiment examined the change in the permeability of the RWM induced by endotoxin, exotoxin, and otitis media using this method. MATERIALS AND METHODSHealthy chinchillas weighing 450 to 550 g were used for this study. These animals were divided into four groups. Groups 1 (n = 6) and 2 (n = 5) were given applica¬ tions of 100 mg of endotoxin from Escherichia coli (serotype Olli : B4, Sigma Chemi¬ cal Co, St Louis) and 50 mg of exotoxin from Staphylococcus aureus (Sigma), respectively, dissolved in 1 mL of Ringer's solution. For group 3 (n = 4), the surgical obstruction of the eustachian tube was performed according to a previous report.16 Group 4 (n = 7) was the control group, receiving no treatment. The permeability of the RWM was measured 48 hours after tre...

No abstract