title: Healing of tympanic membrane after myringotomy during Streptococcus pneumoniae otitis media. An otomicroscopic and histologic study in the rat.
abstract: The purpose of our study was to elucidate the course of healing of the tympanic membrane (TM) when myringotomy was performed during acute otitis media. The early and long-lasting structural changes of the TM were studied in an animal model. Rats were inoculated with Streptococcus pneumoniae (PnC) type 3 in the bulla. When the infection was manifest, myringotomy was performed. On days 4 and 12, and 3 and 6 months after myringotomy, the TM status was checked by otomicroscopy and TMs were prepared for light and electron microscopy. Comparison was made with PnC-infected TMs that were not perforated, as well as myringotomized noninfected TMs. The infection resolved more slowly in myringotomized ears compared to PnC-infected ears that were left untouched. After 6 months, the pars tensa of the myringotomized infected ears was thickened and showed a disorganized collagen structure, compared with myringotomized noninfected ears, in which TMs were normalized. The PnC-infected TMs without myringotomy were completely normalized after 2 months. We conclude that a combination of bacterial infection and myringotomy causes long-lasting changes in TM structure. This impaired structure of the connective tissue could be of importance in chronic middle ear disease as a presumptive site for retraction and perforation of the TM.
authors.affiliation: Department of Otorhinolaryngology, Umeå University, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Magnuson
authors.forename: A
authors.initials: A
authors.lastname: Hermansson
authors.forename: S
authors.initials: S
authors.lastname: Hellström
mesh_terms: D000208:Acute Disease; D000818:Animals; D008297:Male; D009225:Myringoplasty; D010033:Otitis Media / Q000209:etiology* / Q000601:surgery*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013296:Streptococcus pneumoniae / Q000472:pathogenicity*; D018058:Tympanic Membrane Perforation / Q000209:etiology / Q000601:surgery*; D014945:Wound Healing