Complications of cochlear implant surgery

Because the number of cochlear implant candidates has increased in recent years, cochlear implantation has become a routine surgical procedure. The otologists should be aware of the possible complications of cochlear implant surgery. This article shows the various kinds of minor and major complications. The main features of the major complications include: (1) Facial nerve stimulation usually occurs in patients with anomalous ear or even in those without any specific pathology. Although the symptom will diminish by reprogramming certain electrodes, a considerable decrement of speech recognition is inevitable. It is reported that replacement with a modiolar hugging electrode has reduced this symptom when straight electrode was implanted, however, it cannot be adopted in all cases, so that no satisfactory solution is available yet (2) Poor response of the auditory nerve is rare, but it may occur in some congenitally deaf children or in adults who are post-lingually deaf as a result of an ossified cochlea. Patients may be aware only of environmental sounds or may become nonusers of cochlear implants. Reimplantation on the other side or auditory brainstem implant may become an alternative choice of treatment. (3) The electrode extrusion or migration of electrode array may occur a long time after surgery. The cause of this complication is variable, but the split bridge technique, tight packing around the cochleostomy window, or canal wall reconstruction should decrease the occurrence of this complication. (4) And infections occur in only a limited number of cases, but there is a risk of such infections progressing to meningitis and subsequent death as the most serious complication of cochlear implantation. Although most infections subside in response to medical treatment, revision surgery becomes necessary when the skin breaks down. Therefore, an awareness of the early stages of infection is of the utmost importance. To decrease major complication rates, surgeons are required to pay attention to past mistakes and have to be trained in implantation. Because some complications result from device malfunction, manufacturers are also required to improve device design and integrity to attain good outcome.