A cochlear implant can be used in all of the following conditions causing bilateral severe to profound loss:
Cochlear implant electrode(s) stimulate fibres of CN VIII or ganglion cells. It assumes CN VIII is normal to carry impulses. If CN VIII has been cut as in removal of acoustic neuroma cochlear implant is ineffective, instead a brain-stem implant is used to stimulate cochlear nuclei.
Meningitis
Otosclerosis
Ototoxic drugs
Section of CN VIII
Ear