Long-term complications after cochlear implantation

Cochlear implantation has become an effective treatment for many profoundly deaf patients. As with any surgical procedure, a proportion of patients suffer postoperative complications. The aim of this study was to analyze long-term postoperative complications in patients with cochlear implants with a view to improve clinical interventions and propose a consensus for reporting complications.

A total of 406 cases received cochlear implants between December 1985 and April 2007 at Tokyo Medical University (TMU) Hospital. We retrospectively reviewed case notes from 366 patients who had undergone cochlear implantation (215 adults and 151 children) after excluding 40 patients of re-implantation including 13 cases implanted initially at other hospitals. Life-threatening, major and minor complications were examined retrospectively.

Major complications occurred following cochlear implantation in 32 patients (8.7%) who had received their initial implant at TMU Hospital. Revision surgery was required for 30 patients. The mean age at implantation was 33 years 6 months (range, 1 year 9 months to 83 years; median, 37 years). The main etiology of deafness was unknown or progressive (113, 52.6%) in adults and congenital (132, 87.4%) in children. The cause of deafness was meningitis in 41 cases (11.2%), and 26 cases (7.1%) were diagnosed with idiopathic sudden deafness. Flap-related problems (including middle ear infection and/or flap necrosis) developed in 13 cases (3.6%), with 12 cases (7 adults, 5 children) requiring re-implantation. Electrode slip-out occurred in 8 patients (7 adults, 1 child). All adult cases in whom electrodes slipped out underwent implantation before 1994, while the child (1 pediatric case) was operated in 2003. All cases required re-implantation and most cochlear implantations were performed using the modified split-bridge technique after 1997. Six patients (4 adults, 2 children) experienced device failure. Four patients experienced electrode problems. Non-surgical major complications included 1 patient with permanent facial nerve paralysis as a result of thermal injury in 1995. The total number of minor medical and surgical complications was 27, representing 7.4% of all operations.

Many cases of major complications, including electrode problems and facial paralysis, excluding traumatic device failure were considered avoidable by strict operative and postoperative procedures. Some cases of flap infection and traumatic device failure may not be able to be avoided completely, and every possible care should be taken by implant patients and others involved.