Digital imaging: a valuable technique for the postoperative assessment of cochlear implantation

Cochlear implantation with a multi-channel electrode array which provides stimulation via the auditory nerve has become a standard treatment for profound deafness. Postoperative radiography demonstrates electrode position and enables confirmation of satisfactory intra-cochlear electrode placement. The number of active electrodes which have been inserted can be determined and possible complications such as electrode kinking or slippage can be assessed. We evaluated digital radiography with confirmation of electrode position by intermittent fluoroscopy and assessed the relative radiation dose of the digital technique, conventional radiography and CT scanning. Radiation dose for this method usually ranges between 40 microGy and 440 microGy compared with a single exposure on the skull stand which produces a dose to the region of the cochlea of 470 microGy and a CT exposure of 950 microGy. The digital technique is comfortable for the patient, easily reproducible and provides images of high diagnostic quality enabling each electrode to be identified, which is especially valuable in association with postoperative electrode mapping. It also involves a lower radiation dose than conventional radiography. We now use digital radiography for all postoperative cochlear implant assessment.