Electrocochleographic findings in recurrent idiopathic sudden sensorineural hearing loss

Abstract Conclusion: The main differences in electrocochleography (ECochG) between recurrent and nonrecurrent idiopathic sudden sensorineural hearing loss (iSSNHL) were the high prevalence of an abnormally increased action potential (AP) recovery (iR) in nonrecurrent iSSNHL and the very low prevalence of iR in recurrent iSSNHL. An enhanced SP/AP ratio, low AP threshold, low initial hearing level, and up-sloping type of audiogram appear to be favorable prognostic factors in recurrent iSSNHL. Objectives: This study aimed to characterize differences in ECochG findings and other confounding prognostic factors between recurrent and nonrecurrent iSSNHL and to estimate how these findings are related to hearing outcome in recurrent iSSNHL. Methods: ECochG was performed transtympanically in 23 and 42 ears with recurrent and nonrecurrent iSSNHL, respectively. AP recovery was measured using a paired-click stimulation paradigm. Differences in ECochG findings associated with confounding prognostic factors between recurrent and nonrecurrent iSSNHL, and between three outcome groups were assessed. Results: iR was significantly more common in nonrecurrent iSSNHL (16 ears) than in recurrent iSSNHL (1 ear). In the outcome of recurrent iSSNHL, the prevalence rates of an enhanced summating potential (SP)/AP ratio, lower AP threshold, lower initial hearing level, and up-sloping type of audiogram were significantly higher in the cure group than in the improvement and no-recovery outcome groups.