Significance of 1 kHz Pure-tone Threshold in Acute Low-frequency Sensorineural Hearing Loss

To analyze risk factors for acute low-frequency hearing loss (ALFHL), and compare treatment outcomes in the presence or absence of such risk factors.

A case series featuring retrospective chart review.

An academic university hospital.

We included 170 ALFHL patients without vertigo. All of the patients received one of four treatments: low-dose steroid (LD-steroid), high-dose steroid (HD-steroid), LD-steroid and diuretics (LD-combination therapy), and ITDI (intratympanic dexamethasone injection) and diuretics (ITDI-combination therapy). To identify risk factors, we reviewed the clinical features of patients such as age, sex, chief complaint, accompanying symptoms, diabetes, hypertension, time from disease onset, the extent of hearing loss, treatment methods, and 1 kHz involvement.

ALFHL was diagnosed based on the average hearing loss >30 dB at 250 and 500 Hz.

The overall rates of hearing recovery were 70-80% in the four treatment groups. In terms of the prognosis of ALFHL patients, we found that a longer time from disease onset and 1 kHz involvement were independent risk factors for poor prognosis. In addition, we compared treatment outcomes of four treatment methods in the presence or absence of risk factors. In ALFHL patients with risk factors, we found statistically significant differences (p = 0.042) among treatment methods; effectiveness ranged in the order if ITDI-combination therapy, LD-combination therapy, HD-steroid, and LD-steroid.

Risk factors for poor hearing recovery in ALFHL included longer symptom duration and 1 kHz involvement. In ALFHL with such risk factors, combination therapy was more effective than oral steroid therapy.