Electronystagmographic findings in idiopathic sudden hearing loss.

The electronystagmographic findings for 116 patients with unilateral idiopathic sudden hearing loss (ISHL) were analyzed. For the purpose of the study, three groups were formed: patients with normal electronystagmographic (ENG) findings; patients with mild to moderate vestibular injuries consisting of spontaneous horizontal nystagmus or directional preponderance; and patients with severe vestibular injuries indicated by reduced vestibular responses, including paresis of the semicircular canal or lack of response to caloric testing. Clinical and audiologic findings were compared. High correlations were found between both subjective vertigo and abnormal ENG findings and the presence of profound hearing loss at the onset of ISHL. There was an inverse relationship between recovery from ISHL and the ENG findings, namely, as the severity of the vestibular injury increased, the percentage of patients who achieved recovery decreased. Patients with abnormal ENGs had a greater mean hearing loss at onset of ISHL and less mean recovery of hearing than did patients who had normal ENG findings. In addition, patients who had abnormal ENG findings recovered less fully from hearing loss in the high frequencies than from those in the low frequencies owing to the proximity of the basilar turn of the cochlea to the vestibular sense organ.

The relationship of idiopathic sudden hearing loss to diabetes mellitus.

A diabetic subgroup identified from a base population who have experienced idiopathic sudden hearing loss (ISHL) has been studied. In order to assess the relationship between diabetes and ISHL, two non-diabetic control groups were formed, and a comparison of the audiological data between the diabetic and non-diabetic ISHL patient was made. Mean degree of hearing loss and recovery, as well as the mean hearing level of the contralateral ear were analyzed. No statistically significant differences were noted in the audiological pattern of ISHL in diabetics and controls. A similar incidence of recovery was noted for the two groups throughout the mid frequencies; however, diabetic ISHL patients fail to recover as well as in the high frequencies. Preliminary data, while not statistically significant, suggest an increased hearing loss in both the affected and unaffected ear of the older diabetic patient.

The implication of viruses in idiopathic sudden hearing loss: primary infection or reactivation of latent viruses?

Seventy-seven paired serum samples from patients with known idiopathic sudden hearing loss (ISHL) were surveyed using viral serologic methods. Fifteen different viruses and Mycoplasma pneumonia were the agents tested. We determined an incidence of 65% (49/77) of documented significant seroconversions to one or more of the agents surveyed. Multiple agents were involved in 24 of the 49 positive cases we studied. Influenza virus Group B in 14 (18%) and rubeola in 12 (16%) were the most prevalent, followed by Herpes simplex type 1 in 6 (8%), mumps in 6 (8%), influenza Group A3 in 6 (8%), rubella in 5 (7%), and cytomegalovirus (CMV) in 5 (7%).