Contributing factors in the pathogenesis of acquired cholesteatoma: size analysis based on MDCT.

OBJECTIVE: The purpose of this article is to explore the factors that contribute to the occurrence of cholesteatoma. We studied the size of the mastoid air cells and the tympanic cavity using high-resolution CT. MATERIALS AND METHODS: Temporal bone CT scans of consecutive patients with unilateral cholesteatoma and healthy control subjects were retrospectively analyzed. We compared the total volume and the greatest cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity between the affected and unaffected sides in patients with cholesteatoma and in the control subjects. We also compared separately the measured volumes of the cavities of the mastoid air cells and tympanic cavity between the unaffected side of the patients with cholesteatoma and the control subjects. RESULTS: One hundred temporal bones of 50 patients with cholesteatoma and 50 control subjects were included. Both the volume and the cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity in the affected side of the patients with cholesteatoma were significantly smaller than those in the unaffected side (p < 0.001). Moreover, both the volume and the cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity in both affected and unaffected sides of patients with cholesteatoma were significantly smaller than those in control subjects (p < 0.001). The volume of the cavities of the mastoid air cells in the unaffected side of patients with cholesteatoma was smaller than that of the control subjects (p < 0.001). In contrast, no significant difference was found in the tympanic cavity volume between the unaffected side and the control subjects. CONCLUSION: Our results were consistent with the hypothesized contribution of mastoid air cell underdevelopment to the occurrence of cholesteatoma. A small tympanic cavity is less likely to contribute to the occurrence of cholesteatoma.

Sensorineural hearing loss: there is no correlation with isolated dysplasia of the lateral semi-circular canal on temporal bone CT.

BACKGROUND: Inner ear malformations may cause sensorineural hearing loss (SNHL). However, the correlation between the small lateral semi-circular canal (LSCC) and SNHL is controversial. PURPOSE: To determine whether there is a correlation between the two using CT-based measurement. MATERIAL AND METHODS: We retrospectively reviewed the high-resolution CT images of the temporal bone obtained from consecutive patients. A total 136 ears of 68 patients (25 men and 43 women; age range 20-85 years, mean 49.8 years) were included in this study. Patients who were clinically suspected to have otosclerosis were also excluded. Two radiologists independently measured the width and cross-sectional area of the bony island of LSCC. We evaluated the correlation between LSCC bone island width or cross-sectional area and hearing level in all cases using Pearson correlation co-efficients. In addition, we compared hearing levels among the patient group with normal-sized LSCC (≧mean-SD), small LSCC ( 0.05). No significant difference in hearing levels were found among groups of the normal-sized, small and very small LSCC (P > 0.05). CONCLUSION: We conclude that there is no correlation between isolated small LSCC and SNHL.