Conclusion: Factors prognostic of recovery from low frequency sensorineural hearing loss without vertigo are co-occurrence of tinnitus, PTA determined hearing level on the affected side before treatment initiation, and time from onset to treatment initiation. The rate of hearing recovery was higher in the oral steroid than in the intra-tympanic steroid and combined groups.
Objectives: Although many studies have assessed acute sudden hearing loss, few have analyzed low-frequency hearing loss. Clinical characteristics of patients with hearing loss may vary by type of hearing loss. This study, therefore, analyzed the clinical characteristics, recovery rates, and factors associated with hearing recovery in patients with low-frequency sensorineural hearing loss unaccompanied by vertigo.
Method: This study included 50 patients with severe low frequency hearing loss unaccompanied by vertigo and with normal tympanic membrane status who visited hospitals from July 2005 to May 2014 due to sudden tinnitus, ear fullness, or hearing loss. Of these patients, 29 were treated with oral steroids, eight with tympanic steroid injections, and 13 with both. Clinical and auditory characteristics before and after treatment, as well as treatment outcomes, were compared in these three groups.
Results: Age, sex, affected side, co-occurrence of ear fullness, and accompanying chronic diseases were similar in the three groups. All patients started on treatment within 10 days of hearing loss showed significant recovery, with complete recovery, unaccompanied by tinnitus, observed in 10 patients. Treatment outcomes were not affected by hearing thresholds on the unaffected side. Of the patients treated with both oral and intra-tympanic steroids, 39% showed complete recovery, and 77% showed audiometric improvement. The complete recovery rate was significantly higher in the oral steroid than in the other two groups (p = 0.029); and the audiometric improvement rate tended to be lower in the intra-tympanic steroid group than in the other groups. Cure rates, defined as complete disappearance of symptoms and normal findings on pure tone audiograms (PTA), in the oral, intra-tympanic, and combined steroid groups were 49%, 25%, and 23%, respectively. There were no significant differences among the three groups in cure, subjective improvement, and audiometric improvement rates. Factors prognostic of non-recovery of hearing included late treatment initiation (p = 0.044), accompanying tinnitus (p = 0.049), and higher hearing thresholds on the affected side before treatment initiation (p = 0.005).
Keywords: Hearing loss; low tone; prognosis; sudden hearing loss.