Abstract: Objective To investigate the characteristics of auditory brainstem response(ABR)to high-frequency stimulus in young and middle-aged patients with sudden deafness and no history of vertigo or cardiocerebrovascular disease. Methods A total of 46 young and middle-aged patients with sudden deafness and 30 volunteers with normal hearing were enrolled from January 2016 to May 2017. All patients had no history of vertigo or cardiocerebrovascular disease, and all exhibited unilateral onset of sudden deafness. Pure tone audiometry, high-(51.1 times per second)and low-(11.1 times per second)frequency stimulation ABRs were tested for the affected side of patients, the normal side of patients, and both sides of volunteers; the results were categorized as the affected side, normal side, and control groups, respectively. The difference in I-V interpeak latency between high- and low-frequency stimulation ABRs(△IPL)and the rate of ears with abnormalities among the 3 groups were compared. Based on the △IPL of their affected side, patients were subdivided into affected side abnormal, normal, and no △IPL groups; the clinical curative effect was compared among the 3 groups. Based on the △IPL of their healthy side, patients were again subdivided into healthy side abnormal, normal, and no △IPL groups; the clinical curative effect was compared among the 3 groups. Results The test results of pure-tone audiometry were similar in the normal side and control groups(differences between these groups were not statistically significant(P>0.05)). The rate of ears that could not elicit ABRs to high-frequency stimuli and ears with abnormal △IPL in affected side and normal side groups was much greater than the corresponding rate in the control group; these differences were statistically significant(all P<0.05). Patients who could not elicit ABRs to high-frequency stimuli from the normal side exhibited a similar lack of ABRs from the affected side. Patients with abnormal △IPL from the normal side also showed abnormal △IPL from the affected side. The clinical curative effect in the affected side normal group was much better than in the abnormal group and the no △IPL group; these differences were statistically significant(all P<0.05). The clinical curative effect in the healthy side normal group was much better than in the abnormal and no △IPL groups; these differences were statistically significant(all P<0.05). Conclusion For young and middle-aged patients with sudden deafness and no history of vertigo or cardiocerebrovascular disease, it is common to observe abnormal △IPL between high- and low-frequency stimulation ABRs, as well as ears that could not elicit ABRs to high-frequency stimuli. If these characteristics are present on the affected side, they may be present on the healthy side; these characteristics in either side may be associated with a poor prognosis.

Key words: Sudden deafness, Auditory brainstem response, Stimulation rate, Young and middle-aged