Abstract
Objective
To evaluate temporal bone computerized tomography (CT) findings in children with DFNB1 hearing loss (HL) and non-DFNB1 deaf children, using absolute measurements and visual inspection.
Methods
A retrospective case-control series (1998 to 2005) was performed at an academic tertiary center. Children with non-syndromic HL were diagnosed as DFNB1 or non-DFNB1 after screening for GJB2 allele variants and the large GJB6 deletion. After matching for degree of HL, temporal bone CT images were compared in a cohort of 8 DFNB1 children (16 ears) to 9 non-DFNB1 children (18 ears). Visual criteria and absolute measurements were compared against normative values established by Purcell (2003). Absolute measurements between groups were compared using the student t-test. Non-parametric statistical tests were used when appropriate. Significance level was 0.05.
Results
Visual inspection failed to identify 2 patients with abnormalities found using absolute measurements. There was a statistically significant difference in the prevalence of abnormal temporal bone CT findings between DFNB1 (1 of 16 ears) and non-DFNB1 (10 of 18 ears) (p<0.0031, Fisher exact test). Of the absolute measurements, only the mean vestibule width in the non-DFNB1 group (4.195 ± 0.5 mm) was significantly greater than in the DFNB1 group (3.65 ± 0.2 mm) (p < 0.001).
Conclusions
Visual inspection of temporal bone CT images alone may not adequately identify anomalies and should be used in conjunction with absolute CT measurements. Abnormal temporal bone CT findings are significantly less likely in children with DFNB1 when compared to non-DFNB1 children, despite matching for a similar degree of HL.
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