Caloric Test as a Possible Prognostic Indicator in Sudden Deafness / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Dizziness has been known as a prognostic factor in sudden sensorineural hearing loss (SSHL), but it is difficult to describe and quantify its subjective symptoms. Also, dizziness itself cannot imply vestibular dysfunction in SSHL. Comprehensive evaluation of vestibular function may help us understand the extent of lesions in sudden deafness. The purpose of this study is to determine whether an impaired caloric response is associated with disease severity and hearing outcome. SUBJECTS AND METHOD: A retrospective chart review was conducted of 488 patients diagnosed as unilateral SSHL. The patients were divided into two, an abnormal caloric group (canal paresis >20%) and normal caloric group (canal paresis ≤20%). Initial demographic and audiologic findings and final hearing outcomes were compared between the two groups. RESULTS: The initial pure tone averages of SSHL patients of abnormal caloric group and normal caloric group were 75.4±28.4 dB HL and 68.2±25.4 dB HL (p=0.004), respectively. Patients of abnormal caloric test group showed worse hearing outcome across all frequencies compared to those of the normal caloric group. Also, a significant correlation was noted between the magnitude of hearing recovery and canal paresis (r=-0.223, p < 0.001). CONCLUSION: SSHL patients of abnormal caloric test showed worse initial hearing level and poorer hearing outcome. Evaluation of vestibular function in SSHL patients is important because subjective symptoms alone cannot account for vestibular hypofunction patients, and the caloric test can help in the counseling of patients and prediction of hearing outcome in SSHL patients.