Association Between Sigmoid Sinusoidal Tinnitus and Low-Frequency Sensorineural Hearing Loss: A Retrospective Study at a Single Center

BACKGROUND: We aimed to explore the correlation between patients’ sigmoid sinusoidal tinnitus (SST) and low-frequency sensorineural hearing loss (LFSHL) and illustrate the underlying mechanism. MATERIAL/METHODS: Seven healthy volunteers with normal hearing were subjected to 125-, 250-, and 500-Hz pure sound and different white noise-masking intensities. A retrospective analysis was made on the clinical data and postoperative follow-up data of 59 patients with SST in the First Affiliated Hospital of Chongqing Medical University. The patients’ sex, age, chief complaints, affected site, concomitant symptoms, course of disease, pure-tone audiometry (PTA) results, tinnitus discomfort loudness scale results, imaging examination, and complications were collected. RESULTS: The results of the simulation experiment showed that the threshold of each frequency segment was higher after noise masking than before masking; the intensity of noise masking was positively correlated with hearing loss, and the changes of the hearing threshold of the 3 frequencies before and after masking were statistically significant (P<0.05). Fifty-nine patients with SST were documented between January 2015 and January 2020. After the operation, their low-frequency hearing was recovered to normal; 11 cases had significantly alleviated tinnitus and 9 cases were cured. CONCLUSIONS: SST often causes corresponding pseudo-low-frequency hearing loss due to the noise-masking effect. The center frequency of tinnitus appears not to be 250-Hz or 500-Hz octave frequency of PTA, barring the detection of the pseudo-hearing loss in the audiometry chart of most patients. Surgery positively affects patients with SST, and the pseudo-LFSHL can be completely recovered after the operation as a result of tinnitus elimination.