Effects of depletion of complement in the development of labyrinthitis ossificans.

HYPOTHESIS: Labyrinthitis ossificans results in part from the intense inflammatory response to Streptococcus pneumoniae cell wall components. Depletion of complement in Mongolian gerbils following induction of meningitis will reduce the degree of inflammation and subsequent cochlear fibrosis.

STUDY DESIGN: Random prospective study. Histological evaluations were performed with the researcher blinded to the experimental group

METHODS: S. pneumoniae meningitis was induced in 10 control and 18 experimental Mongolian gerbils with an intrathecal injection of the bacteria. Both groups of animals received treatment with penicillin. The experimental group was also treated with cobra venom factor to deplete complement in the animals. Three months after the induction of meningitis, the animals' temporal bones were harvested for histological evaluation.

RESULTS: The decomplemented animals developed significantly less intracochlear fibrosis (P < .01). The mortality rate for the experimental group was 11% compared with 40% in the control group (P = .14).

CONCLUSIONS: Reduction of the intense inflammatory response to the S. pneumoniae cell wall components in suppurative labyrinthitis secondary to bacterial meningitis reduced the degree of labyrinthitis ossificans.