| Abstract #19, Date 2/14/99, Session C, Podium , 2:15p |
| Chronology of labyrinthitis ossificans induced by streptococcus pneumoniae meningitis |
| *V. Nabili (University of California, Davis, School of Medicine); H.A. Brodie, N.I. Neverov (University of California, Davis, Department of Otolaryngology-Head and Neck Surgery) |
Labyrinthitis ossificans consists of novel osteogenesis that fills the normally patent cochlear and vestibular lumen as an end stage sequelae to various pathologies. An animal model, using Mongolian gerbils, was previously developed to induce labyrinthitis ossificans and provide a means to better study the poorly understood pathophysiology. This animal model provides an opportunity to study the chronology of new bone formation in labyrinthitis ossificans in the gerbil. Using serial application of different colored fluorochromes, which deposit in newly forming bone, the timing of bone deposition and bone remodeling can be established. Labyrinthitis ossificans was induced in four groups (n=5) and one group (n=6) of gerbils by an intrathecal injection of live Streptococcus pneumoniae. Group 1 received no fluorochrome labels, while group 2 received 1 label, group 3 received 3 labels, and groups 4, 5, 6 received 4 labels. The temporal bones were harvested after 2 weeks ( group 1), 1 month (group 2), 3 months (group 3), 4 months (group 4), 6 months (group 5), and 12 months (group 6). Seventeen of the twenty six animals that received labels developed ossification demonstrated with fluorescent microscopy. In the animals that went on to develop labyrinthitis ossificans, newly formed disorganized bone began calcifying as early as 3 weeks (label 1) post S.pneumoniae injection. Osteoneogenesis continued as evidenced by the presence of the other labels when first applied at 6 weeks (label 2), and 10 weeks (label 3). Ossification, calcification, and remodeling proceeded through a 12 month course, wherein a reduction of labels was present at 6 months and total disappearance by 12 months. The use of fluorescent stains in this animal model provides a means to establish a timeline of the ossification seen in labyrinthitis ossificans. |