Temporal bone density measurements using CT in otosclerosis.

OBJECTIVE

To assess the bone density around the bony labyrinth in otosclerosis patients and to compare it to that of a control population.

MATERIAL AND METHODS

This was a prospective case-control study. Ten patients with otosclerosis (mean age 42 years; range 24-55 years) and 33 control patients with vestibular schwannoma (mean age 46 years; range 20-71 years) were included. All patients underwent a clinical examination, audiometry and a CT scan comprising axial and coronal views of both temporal bones. In the otosclerosis group, audiometry showed unilateral involvement in six patients and bilateral hearing loss in four. The bone density was measured at the fissula ante fenestram (FAF) and at five other anatomical points on the bony labyrinth.

RESULTS

In the control group, the bone density was similar at the six anatomical points. In the otosclerosis patients, the mean bone density at the FAF was lower than that in control patients (1649+/-99.1 vs 2049+/-13.4 HU; p < 0.01). For patients with FAF bone densities < 2000 HU, a correlation was observed between hearing threshold and FAF bone density.

CONCLUSION

FAF bone density appears to be a good indicator of disease progression, and could serve as a follow-up and prognostic parameter.