The Rationale for It-steroid Injection Treatment for Tinnitus

Corticosteroid administration has been widely used as the empirical treatment for various inner ear diseases such as sudden sensorineural hearing loss (SNHL), Meniere disease, and autoimmune-induced hearing loss for a long time. After Sakata et al. [1] first tried intratympanic (IT) steroid injection to control Meniere disease, IT steroid injection treatment has been used as an alternative option to systemic steroid treatment over the last two decades. Two major lines of evidence support the feasibility of IT steroid injection treatment and explaining its mechanism of action. First, injected steroid into the middle ear cavity can penetrate the round window membrane and diffuse into the inner ear fluid [2,3]. Second, many glucocorticoid receptors and mineralocorticoid receptors have been found in the inner ear structures [4-6]. Moreover, there is a theoretical advantage that IT steroid injection could increase the concentration into the target organ while it could also reduce the systemic steroid exposure; therefore the use of IT steroid injection has become widespread in a short time. Animal studies have demonstrted markedly higher concentration of corticosteroids in the endolymph and perilymph of the cochlea when delivered via the intratympanic route in comparison with systemic administration [3]. After these studies, a large-scale prospective study demonstrated IT-steroid injection treatment was not inferior to oral steroid treatment on sudden SNHL in humans [7]. Recent literature recommends IT-steroid injection not only as an alternative to oral steroid in vulnerable subjects such as diabetic patients, but also for a salvage therapy after failure of initial therapy [8,9].