Additional Supporting Information may be found in the online version of this article.

AR_22586_sm_SuppMovie1.avi4364KSupporting Information Movie 1. Neurotrophins to augment cochlear implantation outcomes-an animated movie. In deaf individuals there is a loss of the mechanosensory and supporting cells within the organ of Corti often leading to a flat epithelium, and a wide variability in the number of remaining viable spiral ganglion neurons within Rosenthal's canal, the neurons responsible for carrying auditory information from the periphery to the central nervous system. This may impact cochlear implant outcomes. As shown in the beginning of this clip, when there are few remaining spiral ganglion neurons and peripheral auditory fibers in proximity to a cochlear implant electrode array, there is the potential for significant spread of the electrical signal prior to reaching its neural target, resulting in a non-specific excitation of neurons and a decreased ability to distinguish sounds of different frequencies. As illustrated in the latter segment of this clip, replication deficient viral vectors have been used in animals to deliver neurotrophins to the inner ear, resulting in increased survival of spiral ganglion neurons and regrowth of peripheral fibers into the basilar membrane area, in close proximity to the cochlear implant electrode array. As a result of this proximity between the individual cochlear implant electrodes and their neural target, there is the potential to diminish current spread and improve frequency selectivity, thereby improving cochlear implant recipients' perception of simple and complex sounds.
AR_22586_sm_SuppMovie2.mpg4200KSupporting Information Movie 2. Live cochlear implant surgery of the left ear. The mastoid bone and facial recess have already been drilled away to gain exposure to the middle ear space and cochlea. The cochlear implant is seen in position for implantation, with the internal device embedded in the skull (bottom right) and the electrode array placed within the mastoid cavity. At higher magnification, the basal turn of the cochlea is well visualized. A small diamond burr is used to create a basal turn cochleostomy, an opening into the scala tympani of the cochlea. Subsequently the cochlear implant electrode array is fully inserted into the cochlea (Video clips provided by and used with permission from Dr. Alexander Arts, Department of Otolaryngology, University of Michigan, Ann Arbor, MI and Dr. Shin-Ichi Usami, Department of Otolaryngology, Shinshu University School of Medicine, Matsumoto, Japan).

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