Auditory brainstem potentials in man evoked by electrical stimulation of the round window

In normal subjects, round-window electrical stimulation provides a sound sensation and supplies brainstem-evoked responses whose form is just the same of those evoked by sound stimulation. This electrical stimulation also provides a sound sensation in more than 90% of cases of total deafness, which means that at least a few auditory nerve fibres are still present. Thus, this test is indispensable when considering surgical rehabilitation with a multichannel cochlear implant. The diagram of this response to an electrical stimulus differs completely in the case of total deafness and in normal subjects. The correlation between the form of these diagrams and the supposed etiology of the deafness is not significant.