Sensorineural Hearing Loss in Experimental Purulent Otitis Media due to Streptococcus pneumoniae

Abstract

\s=b\Sensorineural hearing loss (SNHL) has been described clinically following chronic otitis media with effusion, but to the best of our knowledge, no studies have demonstrated SNHL in an animal model of otitis media. Using the chinchilla model of pneumococcal otitis media, significant SNHL was demonstrated after purulent otitis media, especially at higher frequencies. Animals with otitis media received penicillin G procaine treatment for five days after otitis media with effusion (OME) was first documented; resolution of middle ear infection was confirmed by middle ear effusion culture in all animals. Both the inoculated and uninoculated ears were examined by tone burst\p=m-\ elicited compound action potential at threshold. The inoculated ear showed a marked hearing loss of 13 to 36 dB three to four days after OME was first documented; a hearing loss up to 24 dB persisted two to five weeks after inoculation.The change in the compound action potential was highly significant at all frequencies studied. Conductive losses were largely ruled out because there was no middle ear effusion at death and the tympanogram was normal. Purulent labyrinthitis was ruled out by histopathological study. These results indicate that purulent pneumococcal otitis media in the chinchilla model causes significant SNHL and suggest that the pathogenesis of SNHL associated with chronic OME in humans may be studied in this model. (Arch Otolaryngol 1985;111:794-798) Sensori neural hearing loss (SNHL) has been described in patients with chronic otitis media15; in these studies, deterioration in bone conduc¬ tion has been used as an indication of SNHL. However, presbycusis is also associated with deteriorating bone conduction and must be taken into consideration when interpreting the cochlear losses in chronic otitis media.Paparella et al6 compared bone con¬ duction loss by decade in diseased and normal ears and found an increased incidence of SNHL in patients with chronic otitis media in all decades, suggesting that the SNHL was not due to presbycusis. Walby et al5 also noted an abnor¬ mality in bone conduction in their retrospective study of 87 patients with unilateral uncomplicated chronic sup¬ purative otitis media. However, their study of cochlear histopathology revealed no greater loss of specialized sensorineural structures in infected ears than in normal control ears; hence, they concluded that alteration in the mechanics of sound transmis¬ sion was a more plausible explanation for the hearing loss in chronic otitis media.Chinchillas have been used widely to study otitis media and cochlear function; longitudinal studies are pos¬ sible in this species, with periodic sampling of middle ear effusion, which cannot be easily performed in humans with otitis media. The present study was designed to exam¬ ine relationships between acute puru¬ lent otitis media and cochlear func¬ tion in the chinchilla model. Basic bactériologie and pathologic studies in the chinchilla model of otitis media7"9 and basic neurophysiologic studies in the ch...

Pneumococcal Toxins Reversibly Affect Cochlear Electrophysiology

“…SNHL was observed in high-frequency areas (14,16,20 and 31.5 kHz) thus being in agreement with one previous report [9]. We found that the mean of the threshold changes was approximately 10 dB at 31.5 kHz, 5 dB at 20 kHz and below 5 dB at 16 and 14 kHz.…”

“…Pneumococci produce various toxic proteins such as pneumolysin, autolysin, neuraminidase, hyaluronidase and pneumococcal surface protein A [8]. SNHL following inoculating viable pneumococci has been reported [9]. Recently, the importance of their cell wall component has been emphasized to cause the inflammatory reaction [10].…”

Interleukin 8 Can Affect Inner Ear Function

“…the basal part of the cochlea. These results appear compatible with previous reports concerning the penetration of ototoxic substances through the RWM [22][23][24]. Together with the results of morphological examination, two possible interpretations for cochlear dysfunction by IL-8 may be suggested: one indirect, that such substances as lysosomal enzymes, ROS and NO, suspected of being injurious to cochlear tissues, were released from neutrophils attracted by IL-8 into the middle ear cavity to pass through the RWM and/or from neutrophils attracted by IL-8 in cochlear fluids and spread toward the upper cochlear turns with decreasing concentration; the other is a direct but unknown effect of IL-8 to influence homoeostasis in the cochlea.…”

An association of sensorineural hearing loss in mucosal type of chronic suppurative otitis media

“…It is hypothesised that in CSOM toxins enter through semipermeable round window membrane causing damage to organ of Corti Paparella, Morizona. 3,4 Chronic suppurative otitis media is fairly common disease in our country especially in rural community. 5 WHO in 2004 mentioned, the worldwide prevalence of chronic suppurative otitis media is 65-330 million people and 39-200 million (60%) suffer from clinically significant hearing impairment.…”