Reversal of the inner magnet of a cochlear implant after magnet resonance imaging

Abstract

In general, patients with recent versions of cochlear implants(CIs)can safely undergo Magnetic Resonance Imaging (MRI) within 1.5 T scanners, without the need of inner magnet removal surgery. However, even if they wear tight head bandages on their inner coil, complications can occur in CI users during MRI, such as pain, skin reaction, demagnetization of the internal magnet, and dislocation of the magnet out of its silicon flange. We encountered two cases of reversal of the inner magnet of a CI during MRI examination. In both cases, the inner magnets were reversed by 180 degrees, although they remained in the silicon flange. We ordered a polar-changed extra magnet for replacing the reversed inner magnet in one case, and performed a re-implant surgery of the inner magnet in the other. In recent years, the number of hearing-impaired patients with CIs has been increasing along with expansion of the medical indications for CI in the rapidly aging population of the developed countries. On the other hand, MRI is an indispensable clinical diagnostic tool in modern medical practice. Physicians and paramedics must be aware of possible complications that can occur during MRI in patients with CIs. Prompt assessment and appropriate treatment are important in patients with CIs developing complications during MRI examination.