Loss of auditory receptor cells, hair cells, is the leading cause of sensorineural deafness. Auditory function of hair cells can be replaced by cochlear implant. However, in animal models, spiral ganglion neurons (SGNs), that connect hair cells to brain, degenerate after deafening. This might jeopardize the performance of cochlear implant. We observed activation of neurotoxic immune response in spiral ganglion after deafening. My dissertation focuses on pathogenesis of this immune mediated neurotoxicity.