Utility of temporal bone computed tomographic measurements in the evaluation of inner ear malformations.

ABSTRACT

OBJECTIVE: To investigate whether normative inner ear measurements can assist in the evaluation of sensorineural hearing loss (SNHL). DESIGN: Retrospective cohort review. SETTING: A tertiary care hospital. PATIENTS Computed tomography or magnetic resonance imaging was performed on 188 ears with SNHL and 220 ears without SNHL (204 children) between 2001 and 2004. INTERVENTION Two readers measured the basal turn of cochlea (BTC) lumen, lateral semicircular canal (LSCC) bony island width, superior semicircular canal (SSCC) bony island width, and cochlear height (CH). MAIN OUTCOME MEASURES: A t test was performed comparing measurements in patients with and without SNHL. Interobserver variability was characterized by intraclass correlation coefficients and Bland-Altman plots. RESULTS: The t test results demonstrated no statistically significant differences between inner ear measurements in those with and without SNHL. The intraclass correlation coefficients for BTC lumen, CH, LSCC bony island width, and SSCC bony island width measurements was 0.612, 0.632, 0.869, and 0.912, respectively. Bland-Altman plots revealed systematic biases of 1%, 8%, 10%, and 21% for the BTC lumen, SSCC bony island width, LSCC bony island width, and CH measurements, respectively. CONCLUSIONS: Inner ear measurements in children with and without SNHL are not statistically different. Moreover, the measurements are difficult to interpret because while they demonstrate good reproducibility, they are susceptible to systematic biases. However, use of inner ear measurements is more sensitive in identifying vestibulocochlear dysplasias and should be considered to complement visual analysis.