Comparative study of SSNHL with and without tinnitus: audiologic and hematologic differences.

Background and objectives: Tinnitus is one of the most common symptoms of sudden sensorineural hearing loss (SSNHL), with the incidence of tinnitus in patients with SSNHL ranging from 60% to 90%. Little is known, however, about the specific audiologic and hematologic factors that may be associated with the development of tinnitus. To better understand the relationship between tinnitus and SSNHL, the present study compared audiologic and hematologic factors in SSNHL patients with tinnitus and without tinnitus.

Subjects and method: The present study compared 120 patients with SSNHL with tinnitus and 59 patients with SSNHL without tinnitus at their initial examination. Their audiology and hematologic test results were analyzed, and hearing recovery was determined by comparing the hearing thresholds before and after treatment.

Results: 120 patients with tinnitus showed longer III and V latency in auditory brainstem response (ABR) tests, lower signal-to-noise ratios (SNR) at 2 kHz in transient evoked otoacoustic emissions (TEOAE) tests, and lower response rates at 2 kHz in distortion product otoacoustic emissions (DPOAE) tests of the affected ear (p < 0.05 each) than the 59 patients without tinnitus. However, there were no significant between-group differences in the mean hearing threshold and hearing recovery rate of the affected ear. Patients with tinnitus had significantly worse mean hearing thresholds and hearing thresholds at 4 kHz in the nonaffected ear. The percentages of monocytes and large unstained cells (%LUCs) were higher in the group without tinnitus (p < 0.05), although there were no significant between-group differences in inflammatory markers, such as neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) and platelet-to-lymphocyte ratio (PLR).

Conclusion: Tinnitus accompanying SSNHL may be associated with baseline hearing level, as well as being an indicator of damage to outer hair cells and auditory nerves. Additional studies are needed to evaluate hematologic data in SSNHL patients with and without tinnitus.