INDUCTION OF LABYRINTHITIS OSSIFICANS AFTER PNEUMOCOCCAL MENINGITIS -AN ANIMAL-MODEL

Newly formed disorganized bone fills the open spaces within the otic c apsule in various pathologic conditions, resulting in labyrinthitis os sificans, The pathologic mechanisms of this disease remain poorly unde rstood, To better study the sequence of events and contributing mechan isms involved in labyrinthitis ossificans, an animal model was develop ed, Three groups of Mongolian gerbils received either an intralabyrint hine injection of normal saline solution (group 1) or Streptococcus pn eumoniae polysaccharide capsule antigens (groups 2 and 3), The tempora l bones were harvested after 3 months and serially sectioned, None of the eight control animals (group 1), which received intralabyrinthine injections of normal saline solution had any histologic changes in the ir temporal bones, Nine of the surviving 19 animals in groups 2 and 3 had fibrosis or evidence of early ossification. A fourth group of Mong olian gerbils received two intrathecal injections of live S. pneumonia e organisms. The temporal bones were harvested after 3 months and seri ally sectioned, Fourteen of the surviving 15 animals had fibrosis or o ssification or both, This animal model will provide a method for study of the mechanisms of labyrinthitis ossificans.