Otosclerosis in a Nonendemic Population: Utility of CT Scan and Correlation with Audiometry and Surgical Outcome

Abstract

The incidence of otosclerosis in nonendemic patients is low, and preoperative diagnosis can be challenging. The aim of this study was to evaluate computed tomography (CT) findings in patients with otosclerosis and determine their correlation with audiometric findings and surgical outcome in a nonendemic population. We retrospectively reviewed 17 patients from August 2011 to August 2013 with surgically confirmed otosclerosis who underwent preoperative high-resolution CT scans and pre- and postoperative audiometry. Otosclerotic foci were identified on the scans. The density ratio of these foci was calculated and compared with pre- and postoperative audiometric parameters. One patient with Paget disease was excluded from the study. A total of 19 ears were operated on and included in the data analysis. CT scans were normal in 4 ears (21.1%). Hypodense lesions were detected in the remaining 15 (78.9%) ears and the region of interest mapped out. The density ratio was obtained between the hypodense area and adjacent normal labyrinthine bone. No statistically significant correlation was found between the density ratio and any of the audiometric parameters tested (p > 0.05). The diagnosis of otosclerosis in nonendemic areas is challenging. A preoperative CT scan can be useful when otosclerotic foci are present. However, the density ratio of the otosclerotic foci did not correlate with audiometric parameters or surgical outcome.

High-resolution computed tomography and pure-tone audiometry in patients with otosclerosis in the spongiotic phase

“…11–21 Of note, Png et al . 22 recently found no relationship between tomographic and audiometric findings in this setting. These conflicting results may be a result of different sample sizes or otosclerosis phases across the studies, and diverse ethnicities in the populations studied.…”

“…However, when cases with multiple and simultaneous topographic involvements were analysed, especially when the endosteum and the round window were involved, some associations between audiometric and tomographic data were identified. A retrospective study by Png et al, 22 carried out in a population without endemic otosclerosis, found no significant correlation between the densitometry of the foci on high-resolution CT and the audiometric findings of average air conduction threshold, bone conduction threshold or air-bone gap.…”

“…In contrast, other studies have shown otospongiotic foci to be responsible for sensorineural hearing loss, suggesting an association between their location and pure-tone audiometry measures. [11][12][13][14][15][16][17][18][19][20][21] Of note, Png et al 22 recently found no relationship between tomographic and audiometric findings in this setting. These conflicting results may be a result of different sample sizes or otosclerosis phases across the studies, and diverse ethnicities in the populations studied.…”