Modern auditory prostheses range from implants that impart mechanical energy to the cochlea via the ossicular chain or bypassing a damaged ossicular chain via the round window (round window implants) to implants that, bypassing severely damaged inner ear cells, electrically stimulate the auditory nerve within the cochlea (cochlear implants). Other auditory prosthesis are suitable for electrical stimulation of the central auditory pathways: the auditory brainstem implants which, bypassing a damaged cochlea and auditory nerve auditory, stimulate the brainstem nuclei, and the inferior colliculus implant or auditory midbrain implant which, bypassing damaged brainstem nuclei stimulate the inferior colliculus. With the refinements in implant technology, patient selection criteria for the various different implant devices need to be periodically reconsidered with a view to obtaining increasingly high levels of speech recognition for the different etiologies. We review the latest outcomes, obtained with various implant devices, and propose guidelines for device selection for different etiologies of deafness.
Cochlear Implantation (CI) remains as one of the greatest medical achievements in modern medicine. New and innovative strategies continue to be developed to optimize and improve the functional results of CI surgery. Preservation of residual hearing through a-traumatic surgical techniques and electrode arrays may alter indications. Conditions with profound SNHL with preserved low tone hearing may have several causes and pathology may vary accordingly. In patients with progressive adult-onset SNHL neurons may be conserved even after long duration of deafness. IHCs and OHCs, supporting cells, ganglion cells and dendrites may be preserved in the apical region while in the lower turn despite atrophic organ of Corti and loss of lamina fibers ganglion cells can be present even after 28 years duration of deafness. These spiral ganglion cells may be excellent targets for electric stimulation using EAS technique that combines electric and acoustic stimulation in the same ear and utilizes both low frequency acoustic hearing and electric stimulation of preserved neurons. At the moment we are trying to elucidate the mechanism responsible for this preservation in humans and to use this knowledge for future therapy. Nano-technology may offer new possibilities for focused release of drugs and possibly genes to the inner ear. European project“NanoEar”is a concerted action to develop 3rd generation of nanoparticles (NP) for treatment of inner ear deafness. One goal is to target drugs and genes to specific inner ear cells through so-called multifunctional NP which are degradable, non-toxic, traceable and can be released in a controlled and biocompatible way. The small size of the NP may give new properties for technical advancement but risks must also be thoroughly evaluated. Uppsala is a Swedish partner to evaluate NP uptake in vitro in both human and animal spiral ganglion neurons. In my presentation I will show the system of culture spiral ganglion cells and demonstrate their locomotive behaviour and NP intracellular uptake using time lapse video recording and combined immunofluorescence and confocal microscopy.