Idiopathic Sudden Sensorineural Hearing Loss : Corticosteroid Treatment, the Diagnostic Protocol and Outcome

Idiopathic Sudden Sensorineural Hearing Loss (ISSNHL) is a rapid loss of hearing caused by damage to the cochlea or auditory nerve. Spontaneous recovery has been seen in 32%–81%. The incidence of the ISSNHL has been estimated to be between 5 and 20 per 100,000 per year. Different theories (vascular catastrophes, immunologic damage, infections or intracochlear membrane break) about the etiology have resulted in different treatment policies. The effect of therapy is difficult to evaluate for a single physician who sees just a few patients annually. The aim of the present thesis was: 1) to investigate the current management and treatment of ISSNHL patients in Sweden with regard to outcome, 2) to evaluate whether, in comparison to placebo, the most common drug given in the treatment of ISSNHL in any way influences the outcome, and 3) to analyze which variables such as background data, concomitant disease, audiogram shape and laboratory tests, best can predict the outcome of ISSNHL. A national database was developed with half of all ENT clinics in Sweden participating by submitting a questionnaire for each patient with SSNHL (I-II). The questionnaire covered the patient’s background, current disorder, past and family history of different diseases, examinations, and treatment. Audiograms at the onset of SSNHL and after three months were requested. A randomized placebo controlled multicenter trial (RCT) was performed (III) using a modified version of the questionnaire used in the national database. Prednisolone in high tapering dosage, or placebo was given with a total treatment period of eight days. If recovery was complete, treatment stopped, otherwise medication was continued at 10 mg daily to a total of 30 days from beginning. After an initial pure tone audiogram, new audiograms were taken at three follow-up visits: day eight of treatment, after one month, and after three months. Meta-analysis (IV) was used in order to strengthen the analysis from the RCT by increasing the material with corresponding data drawn from the Swedish national database for ISSNHL. Results from the national database showed that out of 400 patients included in the study with ISSNHL, almost 60% were medically treated, of which nearly 90% were given corticosteroids. Hearing improvement was not statistically associated with receipt of medication. 40% of all patients had an MRI or CT, where 3–4% had acoustic neuroma. 24% of the patients with ISSNHL who had hematological tests taken, had one or more pathological findings. In the RCT, 47 patients were randomized to Prednisolone and 46 to placebo. No significant difference of hearing recovery was observed between the Prednisolone group and placebo group at either first or final follow-up regarding the effect of treatment. Presence of vertigo had significant negative effect on hearing improvement in both groups. Inflammatory signs in laboratory work-up had a positive prognostic effect, irrespective of treatment. The meta-analysis showed no significant difference between the Prednisolone group and placebo/no treatment group (p>0.05). Vertigo at the onset of hearing loss and age had a negative prognostic value equally in all groups and signs of inflammation had a positive. Conclusion: Regardless of diagnostic protocol, treatment of ISSNHL in Sweden is mainly limited to corticosteroids (50%) or to no medical treatment. In a randomized placebo-controlled clinical trial no positive effect of Prednisolone on ISSNHL could be demonstrated. A Meta-analysis of patient data from the Swedish national database for SSNHL and the RCT for ISSNHL demonstrated no effect of Prednisolone on ISSNHL. Is it time to change the focus of research to find new ways to treat ISSNHL