Surgical Experience in Pre-Operative Measurement of Cochlear Duct Length in Cochlear Implant Surgery

Cochlear implant surgery is an auditory prosthesis that helps to restore the hearing in people who have severe to profound sensorineural hearing loss. In view of the variations in individual's cochlear size, appropriate selection of cochlear electrode is important to enable appropriate pitch detection in cochlear implant surgery. In traditional 24 mm electrodes were used in earlier the days. Longer electrode with deeper insertion were always recommended for stimulation of lower frequencies of hearing at apex of cochlear. However, it was avoided to prevent possibility of electrode insertion injury. We are using an indirect measuring method in measuring cochlear duct length by uploading patient's computed topography images of cochlear onto a validated software named "OTOPLAN" prior to cochlear implant surgery. This software can provide information on the morphology of cochlear, which includes width, height, and diameter as well as the cochlear duct length. In results, we recruited 30 patients from age 2-76 years old, who are fitted into the inclusion criteria with total of forty-five cochlear reviewed in 3 years duration. Our patients show an average cochlear duct length of 33.5 mm with a range of 30.1-36.0 mm. Majority of patients were implanted with 28 mm electrode. Patients had an average of 83% of cochlear duct covered with inserted electrode with average 77.8-92.7%. Identification of variation of cochlear anatomy and electrode selection gives an optimal pre-operative planning and appropriate electrode selection in cochlear implant surgery.

The online version contains supplementary material available at 10.1007/s12070-024-05259-6.