Pharmacological Issues in Hearing Rehabilitation.

Surgery aimed at hearing rehabilitation risks damaging residual inner ear function, especially cochlear implant surgery. Pharmacological intervention to reduce this risk has shown great promise in animal models. The challenge is to deliver medication to the appropriate part of the inner ear in appropriate concentrations for long enough to be effective. Barriers to achieving these goals include: the blood/labyrinth barrier, limiting systemic drug delivery to the inner ear, slow rates of diffusion from the base of the cochlea to the apex, limiting intratympanic delivery from the middle ear to the cochlear apex, delayed intracochlear fibrosis, requiring extended medication delivery postoperatively. Intracochlear drug delivery via a drug-eluting cochlear implantation (CI) electrode may solve many of these pharmacologic issues. It is likely that more than one medication will be necessary to maximize inner ear protection and this may include steroids and appropriate growth factors. Such protection may also be helpful for otologic surgical procedures other than CI that have lower risks to hearing.