Cochlear implant electrode insertion: Jacobson's nerve, a useful anatomical landmark.

The classical technique in approaching the scala tympani through the round window niche by way of facial recess has not always been successful. There have been recent reports on false insertion of the electrode array into the hypotympanic cells tracts or infralabrynithine cells tracts. In these cases the round window niche are situated posterior, or obliterated due to bony growth, or sclerosed at the basal turn of the cochlea. Therefore, successful intubation of the scala tympani much depends upon the position of the round window niche and patency of the basal turn of the cochlea. The present study was conducted in an attempt to elucidate factors that determine the ease of insertion of an electrode array, and to by-pass the initial turn of the basal cochlea (hook area). The jacobson's nerve (JN) landmark was used to perform cochleostomy by drilling anteriorly or through the nerve. The inferior segment position of the basal turn of the cochlea studied in relation to the JN and successful intubation of the scala tympani was achieved. Also, critical anatomical measurements were made pertaining to this surgical technique.