Clinical Implication of the Threshold Equalizing Noise Test in Patients With Sudden Sensorineural Hearing Loss

Objective: The aims of the present study were to investigate the prevalence of cochlear dead regions (DRs) in patients with sudden sensorineural hearing loss (SSNHL) and compare the hearing outcome according to the presence of DRs. Study Design: Retrospective chart review. Setting: Tertiary referral center. Patients and Methods: The threshold-equalizing noise (HL) test was performed on a total of 112 ears diagnosed with SSNHL. Ears were divided into two groups based on the presence of DRs. Eighty-two ears belonged to the group without DRs and 30 ears belonged to the group with DRs. There was no difference between the two groups with respect to age, sex, side of affected ear, presence of bilateral SSNHL, presence of vertigo, history of treatment, and initial pure-tone thresholds. Pure-tone audiograms were gathered at the time of initial presentation and at 1, 3, and 6 months after onset of symptoms. Results: The prevalence of DRs was observed to be 29% and was found to be prevalent at 1k and 1.5k Hz in patients with SSNHL. When the hearing thresholds over times were compared between the two groups, subjects with DRs showed significantly poorer hearing outcome compared with those without DRs. The improvements in word recognition scores over times were also less in subject with DRs than those without DRs. Conclusion: DRs are associated with worse hearing thresholds at follow-up audiogram and might be associated with unfavorable hearing outcome in patients with SSNHL.