Turkish Neurosurgery
Magnetic resonance imaging distortion and targeting errors from strong rare earth metal magnetic dental implant requiring revision
Park Seong-Cheol1, Lee Chong Sik Lee, 2, Kim Seok Min2, Choi Eu Jene2, Lee Do Hee1, Lee Jung Kyo1
1Asan Medical Center, Neurosurgery, Seoul,
2Asan Medical Center, Neurology, Seoul,
3College of Medicine, University of Ulsan, Seoul,
DOI: 10.5137/1019-5149.JTN.19327-16.1

Abstract BACKGROUND: Recently, the use of magnetic dental implants has been repopularized with the introduction of strong rare earth metal, for example, neodymium, magnets. Unrecognized magnetic dental implants can cause critical magnetic resonance image distortions. We report a case involving surgical failure caused by a magnetic dental implant. CASE DESCRIPTION: A 62-year-old man underwent deep brain stimulation for medically insufficiently controlled Parkinson’s disease. Stereotactic magnetic resonance imaging performed for the first deep brain stimulation showed that the overdenture was removed. However, a dental implant remained and contained a neodymium magnet, which was unrecognized at the time of imaging; the magnet caused localized non-linear distortions that were the largest around the dental magnets. In the magnetic field, the subthalamic area was distorted by a 4.6 mm right shift and counterclockwise rotation. However, distortions were visually subtle in the operation field and small for distant stereotactic markers, with approximately 1–2 mm distortions. The surgeon considered the distortion to be normal asymmetry or variation. Stereotactic marker distortion was calculated to be in the acceptable range in the surgical planning software. Targeting errors, approximately 5 mm on the right side and 2 mm on the left side, occurred postoperatively. Both leads were revised after the removal of the dental magnets. CONCLUSION: Dental magnets may cause surgical failures and should be checked and removed before stereotactic surgery. Our findings should be considered when reviewing surgical precautions and making distortion-detection algorithm improvements.

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