Potential insertion complications with cochlear implant electrodes
Akira Ishiyama, Frank Risi, Paul Boyd
Abstract
Objectives: The aim of this discussion paper and literature review was to estimate the incidence of a variety of complications associated with the surgical placement of cochlear implant (CI) electrode arrays and to discuss the implications and management of sub-optimal electrode placement.Results: A review of the peer-reviewed literature suggests that the incidence of incomplete electrode insertion and kinking is more prevalent in straight arrays and not more than about 2% in CI recipients with normal cochlear anatomy/patency. Incidence of tip fold-over is greater with perimodiolar arrays but also occurs with straight arrays and is typically less than 5%. Conversely, electrode migration is more common with straight arrays, and high rates (up to 46%) have been reported in some studies. Scalar translocations have also been reported for both perimodiolar and straight arrays. Higher rates have been reported for stylet-based perimodiolar electrodes inserted via cochleostomy (up to 56%), but with much lower rates (<10%) with both sheath-based perimodiolar arrays and lateral wall arrays.Electrode positioning complications represent a significant proportion of perioperative CI complications and compromise the level of benefit from the device. Careful surgical planning and appropriate pre- and intraoperative imaging can reduce the likelihood and impact of electrode positioning complications. There is also evidence that newer array designs are less prone to certain complications, particularly scalar translocation.Conclusions: It is important that implanting surgeons are aware of the impact of sub-optimal electrode placement and the steps that can be taken to avoid, identify and manage such complications.