Temporal Bone Posterior Wall Defect, a New Clinic Entity?

To define clinical and audiological findings in patients with temporal bone posterior wall defects (TBPWD) and to investigate possible relationships between these findings and the characteristics of the defect.

The computed tomography (CT) views of 1198 patients with vestibulocochlear symptoms between 2007 and 2012 were retrospectively evaluated, and TBPWD and associated anomalies were investigated. Patients who had TBPWD were called back, and clinical and audiological examinations (tympanometry, pure tone audiometry, acoustic reflexes, and otoacoustic emission) were performed.

Twenty-eight (2.34%) patients had TBPWD. Twenty-three of them were eligible for the study. Size of the defect was significantly correlated with the presence of tinnitus and/or vertigo (p<0.005). The cut-off values for the largest size of TBPWD were 1.65 mm [sensitivity: 0.67 and specificity: 0.77 (95% CI: 0.58-0.97); p=0.04] in case of the presence of tinnitus and 1.85 for vertigo (sensitivity: 0.78 and specificity: 0.86 (95% CI: 0.67-0.99); p=0.006). In pure tone audiometry tests, mixed-type hearing loss was present in four (17%) patients, sensorineural hearing loss was present in three (13%) patients, and conductive-type hearing loss was present only in one (4%) patient. Otoacoustic emission tests revealed significant differences in signal/noise ratios at frequencies of 500, 750, 1000, and 6000 Hz.

For the first time in the literature, we defined clinical and audiological findings in patients with TBPWDs. These defects seem to cause more prevalent symptoms of vertigo and tinnitus and disturb the audiological characteristics of patients.