The Importance of Intra-Operative Radiograph in Cochlear Implant Surgery for Correct Positioning of the Electrode Array

Background: In cochlear implantation surgeries, correct positioning and full insertion of the electrode array in the scala tympani is crucial and with major influence on the post-operative hearing outcome. Intra-operative plain radiograph is one of the methods to confirm a properly placed electrode.

Objective: To demonstrate the importance of intra-operative, post insertion (before awakening the patient) imaging in cochlear implantation surgeries.

Methods: We perform intra-operative post-insertion plain radiographs in the cochlear view in all cochlear implantation surgeries. The cases of 3 patients with normal inner-ear anatomy, in whom a non-optimal position of the electrode array was detected intra operatively, are described.

Results: Between the years 2009-2017, 280 cochlear implantations were carried out in our department. In 3 cases a non-optimal position of the electrode array was detected by an intra-operative plain x-ray. 1) A two year old male with congenital bilateral sensorineural hearing loss (SNHL). Radiography demonstrated fold over of the electrode`s tip. Immediate re-insertion was smooth and repeat imaging showed the electrode in place. 2) A 22 year old male with prematurity and bilateral congenital SNHL was without responses in telemetric post insertion testing. In imaging it was suspected that the electrode array was out of the cochlea, probably in a hypotympanic cell. Cochleostomy was enlarged and repeat post-insertion imaging was good. 3) An eleven months old male with 21 trisomy and congenital bilateral SNHL. Radiography showed a partially inserted electrode. Re-insertion and imaging were good. All patients had good device and hearing outcome.

Conclusion: Non-optimal positioning of electrode in cochlear implantation surgery is not common but when it occurs and overlooked it may substantially influence functional outcomes. Intra operative plain radiograph is a quick method to identify and correct the problem before the patient is awakened.