Preoperative Radiologic Assessment of Facial Nerve in Cochlear Implant Surgery

Facial nerve palsy was reported as a complication of cochlear implant surgery at a rate as high as 1%–3% [3, 4]. Even though temporary, it may have a profound effect on the patient’s well being. Our clinical impression was that the knowledge of the anatomical relationship of the facial nerve to various adjacent structures in the surgical field may help avoid this complication and also influence the decision on which side to implant. Facial recess, the distance from the facial nerve to the external auditory canal, and the distance from the facial nerve to the round window niche were previously measured [1,2]. However, we believe that these parameters are insufficient in predicting the likelihood of facial nerve palsy in cochlear implant surgery. Of 20 patients operated on in our departmet since 1989, two patients (10%) had temporary facial palsy that resolved spontaneously after 2 weeks in one patient and 6 weeks in the other. In one additional patient (5%), the round window niche could not be reached through the posterior tympanotomy approach and a canal wall-down mastoidectomy had to be performed.