Simultaneous idiopathic bilateral sudden hearing loss - characteristics and response to treatment

The aetiology of sudden hearing loss is poorly defined; however, infectious, vascular and neoplastic aetiologies are presumed to be responsible. In addition, the aetiology of bilateral sudden hearing loss is also unknown.

The objective of this study is identify the characteristics and treatment response of simultaneous bilateral sudden hearing loss.

This is a case-control study that practised in tertiary care academic centre. 132 patients with sudden hearing loss who were treated with systemic steroid and hyperbaric oxygen together were included. 26 patients had bilateral sudden hearing loss and 106 patients had unilateral sudden hearing loss. Patients were evaluated with clinical, audiological and radiological examinations and laboratory tests were done. Findings and response to treatment of the patients were compared.

The mean ages of patients with unilateral and bilateral sudden hearing loss were 42.0 years and 24.5 years respectively with a statistically significant difference (p<0.001). Immune response markers were more prevalent in bilateral sudden hearing loss. Pre-treatment audiologic thresholds were 69.1dB for unilateral sudden hearing loss and 63.3dB for the left ears and 67.6dB for the right ears for bilateral sudden hearing loss without significant difference. Post-treatment average hearing threshold in unilateral sudden hearing loss was 47.0dB and 55.4dB for the left ears and 59.0 for the right ears in bilateral sudden hearing loss. Average hearing improvement in unilateral sudden hearing loss group was significant (p<0.001) in spite of it was not significant in bilateral sudden hearing loss group for both ears. Between the groups; there was a significant difference for hearing improvement favouring unilateral sudden hearing loss (p<0.001). Tinnitus scores decreased significantly in both groups of patients (p<0.001) in spite of there was no significant difference between the groups of patients.

Patients with bilateral sudden hearing loss showed lower age, worse prognosis and higher rate of positive immune response markers. Cardiovascular risk factors seem to have an important role in the aetiology of unilateral cases whereas this importance was not present in bilateral ones.