Objective:

We analyzed pure-tone and speech audiometric results from a prospective trial of anti-inflammatory treatment of subjects with active autoimmune inner ear disease (AIED). We sought to characterize the pattern and size of the treatment effect as reflected in clinical audiometry and to identify audiometric predictors of response to steroid treatment of AIED.

Subjects:

Adult participants demonstrated clinically established criteria for AIED (n= 116). Eligibility required audiometric evidence of active AIED as indicated by idiopathic sensorineural hearing loss with threshold elevations within 3 months of enrollment.

Methods:

We evaluated audiometric changes after 4 weeks of treatment with pharmacologic doses (60 mg/day) of prednisone. We examined the relationship between audiometric pure-tone thresholds at baseline and changes in word intelligibility score (WIS) using parametric and nonparametric analyses. Magnitudes of change were assessed using independent or paired t-tests. Separate analyses were performed on subgroups that did or did not show improved WIS score with steroid treatment.

Results:

Overall mean pure-tone averages improved from baseline to closeout of prednisone treatment in better hearing ears from 52.4 to 48.3 dB (p<. 0001). Mean WIS improved in the better ear from 71.4% to 78.1%(p<. 0001). Of pure-tone measures, only the six-tone average showed significant correlation with both the absolute improvements in WIS and with the percentage change in WIS after treatment. Individual frequencies at baseline showed no significant relationship with changes in WIS score after treatment. In 69 (59.5%) of 116 subjects, WIS improved (range, 2-80%) in the better ear. In these subjects, the baseline pure-tone thresholds and pure-tone averages correlated significantly and positively with improvement in WIS.

Conclusions:

Steroid treatment in AIED-mediated hearing loss produce variable but significant hearing gains. Neither a focal, cochleotopic region of greatest vulnerability to AIED nor frequency-specific amenability to treatment were evident. We did observe that analysis of predictors and the degree of treatment effect vary with different approaches to measuring change in the WIS. Depending on the approach adopted, the size of the treatment effect may be greatest across intermediate hearing levels at baseline. These observations offer an audiometric database that may enable greater precision in judging clinically meaningful parameters for future studies of AIED treatment and other interventions for sensorineural hearing loss.

BACKGROUND

Air and bone conduction thresholds and word recognition ability comprise the basic clinical indices of auditory function. The goal of pure-tone testing is to obtain a representation of the softest intensity heard across critical frequencies, comparing observed thresholds to normative data. Word recognition testing probes the ability to perceive, process, and verbally reproduce phonologic units that comprise spoken words. The word intelligibility score (WIS) is the percentage of words a patient can repeat at a comfortable listening level. Stimuli are phonetically balanced, single-syllable words that have a common occurrence in everyday speech. The WIS can provide insight regarding level of difficulty in everyday conversational speech.