Cochlear implant magnet dislocation after MRI: surgical management and outcome.

Purpose: An increasing number of cochlear implant (CI) users is examined by magnetic resonance imaging which may cause the displacement of the implant magnet. This complication prevents the usage of the external processor and has to be treated surgically in most cases. The purpose of this study is to analyze the results of the surgical intervention and the consequences for the CI recipients.

Methods: The retrospective study was conducted at a tertiary referral center. From the patient care records between October 2014 and July 2018, 9 cases were reviewed that had undergone MRI after cochlear implantation and had experienced magnet displacement.

Results: Nine patients from 9 to 74 years of age were identified with MRI-induced magnet displacement. Implants of different manufacturers were affected (8 × Cochlear, 1 Advanced Bionics) but did not include the latest 3 T MR conditional product generation. The patients reported pain, swelling, redness above the implant and/or a noticeably dislocated magnet. One-third of the MRI examination were conducted in external radiological sites without any precautions such as a compression bandage. Surgical magnet repositioning was successful in all but one case with postoperative implant infection and consecutive explantation. In total, the patient was unable to use his CI for 420 days (1.2 years) after the MRI examination. The remaining eight patients averaged 29 days between MRI-related magnet dislocation and CI re-activation.

Conclusions: The present study shows that in the majority of cases a surgical magnet reposition is possible without complications, and thus the time of nonuse of the CI is usually low. Nevertheless, there is a risk that in individual cases significant medical, functional, social and economic consequences for patients may occur. The presented data demonstrate that the indication to perform MRI scans in CI users needs to be further critically considered. An attentive, critical assessment of an MRI indication by both the initiating physician (usually not an ENT specialist) and the performing radiologist is mandatory.