Prognostic Factors Associated with Recovery from Recurrent Idiopathic Sudden Sensorineural Hearing Loss: Retrospective Analysis and Systematic Review

Although idiopathic sudden sensorineural hearing loss (ISSNHL) is uncommon, recurrent ISSNHL is even rarer. The knowledge about factors associated with patient recovery from recurrent episodes is needed to counsel and treat the patients. Medical records of patients admitted for high dose oral steroid therapy for recurrent ISSNHL between January 2009 and December 2021 were reviewed. Their demographic and clinical characteristics, co-morbid symptoms, and audiologic results were analyzed. The 38 patients admitted for treatment of recurrent ISSNHL included 14 men and 24 women. Recovery rates after the first and recurrent episodes of ISSNHL were 78.9% and 63.2%, respectively. Patients who recovered after recurrent episodes showed significantly higher rates of ear fullness symptoms and early treatment onset than those who did not recover (p < 0.05 each). Of the 30 patients who recovered after the first episode, those who had ear fullness symptoms (p < 0.05, odds ratio (OR) 0.1, 95% confidence interval (CI) 0.01–0.76) and who showed a lower initial hearing threshold (p < 0.05, OR 1.06, 95% CI 1.01–1.12) during the recurrent episode showed significantly better or similar recovery than after the first episode. Ear fullness symptoms and less initial hearing loss were associated with a more favorable prognosis after intial than after recurrent ISSNHL.