Extent of Inner Ear Lesion as a Prognostic Factor in Idiopathic Sudden Hearing Loss

Background and Aim: Vestibular involvement in cases of idiopathic sudden hearing loss (ISHL) is common and is reported to be an important prognostic factor. The aim of this study was to evaluate the extent of inner ear lesion in ISHL and to correlate it with the severity of hearing loss and the degree of short-term recovery.

Material and Methods: Ninety-six patients with unilateral ISHL were subjected to a standard protocol of neurotological evaluation. All subjects were hospitalized and treated similarly. A group of 35 healthy volunteers was also enrolled in the study. The results of the VEMP test and the caloric test were measured and compared with the initial and final audiograms of each patient. Each inner ear lesion was ranked into one of three groups according to the results of vestibular tests: complete (group A), partial (group B), and cochlear lesion only (group C). A statistical analysis was done to correlate severity of inner ear damage with severity of hearing loss and early recovery rate.

Results: In total, 22 patients were ranked in group A, 35 in group B, and 39 in group C. Profound hearing loss appeared in 54%, 23%, and 23% of cases in each group, respectively. However, early recovery was shown in 74% of patients of group C, 54% of cases of group B, and in only 5% of subjects included in group A.

Conclusions: Our study results revealed a significant positive correlation between the extent of inner ear lesion and severity of hearing loss and a significant negative correlation between the extent of inner ear lesion and the grade of early recovery. This means that, in ISHL cases, the more the inner ear is affected the less chance there is for recovery.