Pharmacological influence on inner ear endothelial cells in relation to the pathogenesis of sensorineural hearing loss.

Abstract

Despite an increasing incidence of acute sensorineural hearing loss, the pathogenesis of this disease remains uncertain. While viral infection of the stria vascularis, organ of Corti or spiral ganglion cells is discussed in the American literature, a vascular genesis with resulting impaired perfusion of the inner ear is favoured by European investigators. Although both hypotheses are supported by different therapeutic strategies to regain normal hearing, the influence of spontaneous remission remains unclear. This study aims at combining these seemingly opposing concepts with the assumption of an immunologically mediated vasculitis with consequent cochlear hypoperfusion. We already know from other organs that during viral vasculitis circulating immunoglobulins are deposited perivascularly, which leads to a local decrease in perfusion and tissue hypoxia. Also in autoimmune diseases, perivasculitis is common with the endothelium playing a major role at the initial stages of the disease. These endothelial cells promote vasculitis by secreting pro-inflammatory cytokines like IL-1, IL-6 or TNF-alpha in addition to the expression of adhesion molecules. Due to the persistence of these immunopathological mechanisms stenosis or atresia with ischaemic necrosis results. To examine whether this pathomechanism is also important in inner ear dysfunction, the immunological response after stimulation of the cochlear endothelium of guinea pigs was determined. In addition, the influence of corticosteroids on this immune cascade was examined.