Displacement of the magnet after cochlear implantation due to MRI-induced movement

Overview

Introduction: Currently, the criteria for cochlear implantation are significantly expanding and magnetic resonance imaging (MRI) is so much more accessible that it is very likely that cochlear implant recipients will undergo this examination several times in their lifetime. During MRI examinations, there is a risk of magnet dislocation in cochlear implant recipients, especially with older models. Case report: We present a 31-year -⁠ -old woman with severe to profound postlingual bilateral hearing loss, who underwent cochlear implantation on the right side in January 2017. The patient was referred to Department of Otorinolaryngology, Head and Neck surgery in University hospital in Bratislava by a general surgeon due to pain, redness and swelling of the right temporal region at the site of the cochlear implant. The symptoms appeared immediately after undergoing a brain MRI recommended by a neurologist for suspected polyneuropathic syndrome. The magnet displacement was palpable and radiologically confirmed. We performed a surgical revision under local anesthesia. Since new MRI examinations of the brain and musculoskeletal system were required to rule out a neurological diagnosis, we had temporarily inserted a non-magnetic plug, which we replaced with a magnetic one after some time. The implant was functional and used on a headband during this entire period. Discussion: Magnet displacement is less frequent, serious complication after cochlear implantation. In literature, MRI-induced dislocation is the most frequently reported cause of magnet migration. Manufacturers recommend preventive measures such as bandages or head splinting during MRI. The introduction of new generation of cochlear implant with the freely rotating and self-aligning magnet has reduced the incidence of displacement. Partial or complete displacement leads to surgical intervention under general or local anesthesia. Conclusion: In a cohort of > 600 patients implanted in our clinic, this is the first and only case of magnet dislocation induced by MRI examination. The increased need and use of MRI may lead to an increased number of magnet displacements mainly in older types of cochlear implants or in case of violation of the instructions recommended by the manufacturer.

Keywords:

cochlear implant – magnet displacement after MRI examination