Sensorineural hearing impairment is caused by pathologies within the cochlear portion of the inner ear or the central auditory pathway. Within the last decade, tremendous progress has been made in inner ear biology, thus greatly increasing our understanding of congenital and acquired inner ear pathologies. Moreover, the discovery of hair cell regeneration and the presence of neuronal stem cells in the cochlea has raised hopes of being able to treat the causes of sensorineual hearing impairment in the mid-term future. To do so, the regenerated cells will have to be reinnervated through the peripheral axons of the spiral ganglion neurons (SGNs). So far, most factors with the potential to guide peripheral axons of SGNs have been investigated in the developing cochlea of rodent models but not in humans. Remaining SGNs can already be directly stimulated electrically by cochlear implants, electrode arrays surgically inserted into the cochlea, providing effective treatment for severe cochlear hearing impairment.