[Analysis of prognostic factors of low-frequency type of sudden sensorineural hearing loss]

Objective: To investigate the prognostic factors of patients with low-frequency type of sudden sensorineural hearing loss. Methods: From February 2017 to February 2019, adult patients with unilateral low-frequency type of sudden sensorineural hearing loss in Department of Otological Medicine, Shandong Provincial ENT Hospital, Shandong University were selected. All patients were examined by audiology, vestibular function evaluation, imaging examination and serum thyroid function test; the same treatment program was given, the curative effect was recorded and followed up for more than 3 months. SPSS 20.0 software was used to analyze concomitant symptoms (tinnitus, ear tightness, echo, rotatory vertigo), degree of deafness, inducement of deafness, basic disease, vestibular function (caloric test), electrocochleogram, inner ear gadolinium enhanced MRI radiography and thyroid function on prognosis of patients. Results: Among the 155 patients, 76 cases were cured (49.0%), 1 case was markedly effective (0.6%), 19 cases were effective (12.3%), and 59 cases were ineffective (38.1%). The total effective rate was 61.9%. Among them, 24 cases (15.5%) had hearing fluctuations during follow-up, and 1 case (0.6%) developed Meniere's disease. Univariate analysis showed that vestibular function, electrocochleogram and inner ear MRI were correlated with prognosis. Multivariate logistic analysis showed that ear tightness, vestibular function, electrocochleogram and inner ear MRI were correlated with the prognosis of the patients. The two analyses showed that tinnitus, echo, rotational vertigo, degree of deafness, predisposing factors and underlying diseases were not significantly correlated with the prognosis of the patients (all P>0.05). Rotational vertigo was closely related to gender, and women had a high incidence. There was a significant correlation between the degree of deafness and prognosis in patients with course of less than 1 week (P<0.05). The abnormal rate of vestibular function in patients with course of disease ≤ 1 week was significantly different from that>1-≤2 and>2-≤4 weeks (P<0.05). The rate of abnormal thyroid function was significantly higher than that of normal people (P<0.05), but there was no significant correlation between thyroid dysfunction and hearing prognosis (χ(2)=0.009, P=0.923) . Conclusions: The prognosis of low-frequency sudden sensorineural hearing loss is not related to clinical symptoms, inducements, underlying diseases and serological abnormalities of thyroid function, but the degree of deafness is positively related to the prognosis within 1 week from onset. Abnormal thyroid function is one of the risk factors of happening with low-frequency descending sudden deafness. Abnormal vestibular caloric test, electrocochleogram and endolymph hydrops are the factors of poor prognosis.