New Method to Save Displaced Cochlear Implants


11 year old boy with congenital profound hearing loss and a Mondini malformation with single cavity cochlea underwent cochlear implant surgery for a limited auditory benefit in 2012. Post op Xray showed full insertion of all 22 electrodes.

Good ling six sounds detection noted immediately after switch on. CAP score revealed 4 as the maximum attained level out of 12. Two and half years later fluctuation in hearing , especially non detection of high frequency ling sounds ‘ss’ and ‘sh’ reported despise multiple mappings. Xray revealed electrode displacement, 13electrodes were extracochlear.

The standard advice in this situation is to take the implant out and fix a new one. Our patient couldnot afford this and we designed an off label technique to find out implant viability.The cochlear implant electrode is designed to be in a fluid environment and in middle ear air it was shown as open circuit. IMPEDANCE TELEMETRY ( NRT ) WAS DONE AFTER INSTILLING NORMAL SALINE INTO MIDDLE EAR TO RULE OUT ELECTRODE DAMAGE, where all the open circuit electrodes except 2 showed normal impedance values. So reinsertion of the same electrodes was done. Premorbid CAP score of 4 achieved immediately after mapping.