Rofo 2014; 186(07): 680-685
DOI: 10.1055/s-0033-1356238
Head/Neck
© Georg Thieme Verlag KG Stuttgart · New York

Magnet Dislocation: An Increasing and Serious Complication Following MRI in Patients with Cochlear Implants

Magnetdislokation – eine zunehmende und folgenreiche Komplikation nach MRT bei Patienten mit Cochlea Implantat
F. Hassepass
1   Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Freiburg
,
V. Stabenau
1   Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Freiburg
,
S. Arndt
1   Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Freiburg
,
R. Beck
1   Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Freiburg
,
S. Bulla
2   Department of Diagnostic Radiology, University Medical Center Freiburg
,
T. Grauvogel
1   Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Freiburg
,
A. Aschendorff
1   Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center Freiburg
› Author Affiliations
Further Information

Publication History

06 August 2013

24 October 2013

Publication Date:
04 February 2014 (online)

Abstract

Purpose: Cochlear implantation (CI) represents the gold standard in the treatment of children born deaf and postlingually deafened adults. Initial magnetic resonance imaging (MRI) was contraindicated in CI users. Meanwhile, there are specific recommendations concerning MRI compatibility depending on the type of CI system and the device manufacturer. Some CI systems are even approved for MRI with the internal magnet left in place. The aim of this study was to analyze all magnet revision surgeries in CI patients at one CI center and the relationship to MRI scans over time.

Materials and Methods: Between 2000 and 2013, a total of 2027 CIs were implanted. The number of magnet dislocation (MD) surgeries and their causes was assessed retrospectively.

Results: In total 12 cases of MD resulting from an MRI scan (0.59 %) were observed, accounting for 52.2 % of all magnetic revision surgeries. As per the labeling, it was considered safe to leave the internal magnet in place during MRI while following specific manufacturer recommendations: MRI intensity of 1.5 Tesla (T) and compression head bandage during examination.

Conclusion: A compression head bandage in a 1.5 T MRI unit does not safely prevent MD and the related serious complications in CI recipients. We recommend a Stenvers view radiograph after MRI with the internal magnet in place for early identification of MD, at least in the case of pain during or after MRI examination. MRI in CI patients should be indicated with restraint and patients should be explicitly informed about the possible risks. Recommendations regarding MRI compatibility and the handling of CI patients issued with MRI for the most common CI systems are summarized.

Key Points:

• MRI in CI patients: manufacturer recommendations must be followed.

• Magnet dislocation due to MRI is a serious complication.

• In case of suspected magnet dislocation: Use Stenvers view radiograph for diagnosis.

• Instant presentation to a CI center is mandatory for proper management of dislocation.

• Immediate CI revision surgery must be performed in the case of magnet dislocation.

Citation Format:

• Hassepass F, Stabenau V, Arndt S et al. Magnet Dislocation: An Increasing and Serious Complication Following MRI in Patients with Cochlear Implants. Fortschr Röntgenstr 2014; 186: 680 – 685

Zusammenfassung

Ziel: Das Cochlea-Implantat (CI) repräsentiert den Goldstandard in der Therapie von gehörlos geborenen Kindern und postlingual ertaubten Erwachsenen. Initial war die Magnetresonanztomografie (MRT) bei CI-Trägern kontraindiziert. Inzwischen gibt es je nach Implantattyp unterschiedliche Richtlinien zur MRT-Tauglichkeit, sodass bei manchen Systemen sogar mit in situ belassenem internen Magneten eine MRT möglich ist. Ziel dieser Arbeit war die Analyse aller Magnetrevisionsoperationen eines CI-Zentrums bei CI-Patienten und deren Zusammenhang zu MRT-Untersuchungen im zeitlichen Verlauf.

Material und Methoden: Zwischen 2000 – 2013 wurden insgesamt 2027 CIs implantiert. Die Anzahl Magnetrevisionsoperationen und deren Ursachen besonders im Zusammenhang mit MRTs wurde retrospektiv ausgewertet.

Ergebnisse: Insgesamt wurden 12 Fälle einer Magnetdislokation als Folge einer MRT-Untersuchung beobachtet (0,59 %), welche 52,2 % aller Magnetrevisionsoperationen ausmachten. Die Dislokationen nach MRT traten auf, obwohl alle Sicherheitsempfehlungen des Herstellers befolgt wurden: Intensität der MRT bei 1,5-Tesla (T) und Anlage eines Druckverbands im Bereich des CI vor der Untersuchung.

Schlussfolgerung: Der teilweise von Herstellern empfohlene Kompressionsverband im 1,5-T-MRT scheint selbst bei MRT-kompatiblen CIs eine Dislokation des internen Magneten und die damit einhergehenden teils schweren Komplikationen nicht vollständig auszuschließen. Wir empfehlen eine Röntgenuntersuchung nach Stenvers nach erfolgter MRT bei MR-kompatiblem CI und in situ belassenem Magneten zur frühzeitigen Identifizierung einer Dislokation – zumindest im Falle von Schmerzen während oder nach der MRT. Die MRT bei CI-Patienten sollte trotz inzwischen MR-kompatibler Systeme zurückhaltend indiziert und der Patient explizit über eventuelle Folgen aufgeklärt werden. Empfehlungen hinsichtlich der MRT-Kompatibilität und dem Umgang im MRT bei den gängigsten CI-Systemen werden zusammengefasst.

Deutscher Artikel/German Article

 
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