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Correspondence  |   October 2015
Occupational Hazards of Exposure to Magnetic Resonance Imaging
Author Notes
  • Mayo Clinic Arizona, Phoenix, Arizona (A.G.). gorlin.andrew@mayo.edu
  • (Accepted for publication June 22, 2015.)
    (Accepted for publication June 22, 2015.)×
Article Information
Correspondence
Correspondence   |   October 2015
Occupational Hazards of Exposure to Magnetic Resonance Imaging
Anesthesiology 10 2015, Vol.123, 976-977. doi:10.1097/ALN.0000000000000826
Anesthesiology 10 2015, Vol.123, 976-977. doi:10.1097/ALN.0000000000000826
To the Editor:
The recently published Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging does not comment on the occupational hazards of magnetic resonance imaging (MRI) exposure for anesthesia providers.1  Transient sensory effects such as vertigo, nausea, dizziness, metallic taste, and visual phosphenes during exposure to MRI have been widely reported in the radiology literature.2  Vertigo is the most common and potentially most problematic of these symptoms. de Vocht et al.3  surveyed workers in an MRI scanner manufacturing plant, and 22% of the respondents reported experiencing vertigo while at work. In a survey of nurses working in MRI, 7% reported vertigo or dizziness and 12% reported an illusion of movement.4  Although not a widely recognized phenomenon in the anesthesia community, we recently published a report of MRI-induced vertigo in a nurse anesthetist taking care of a patient in a 3-Tesla scanner.5 
The exact mechanism of MRI-induced vertigo is unclear, but there may be separate contributions by static and time-varying magnetic fields.6  Moreover, recent work suggests that the magnetic field induces electrical currents in the endolymph of the vestibular apparatus of the inner ear. This causes deflection of the stereocilia in the hair cells of the cupula, which is then in turn erroneously interpreted by the brain as rotational movement.7  Regardless of the precise physiology, it is well established that the risk of vertigo increases with the field strength of the MRI scanner, the proximity to the bore of the MRI scanner, and the rate of movement (linear and rotational) within the magnetic field. Because they need to move around inside the MRI room and often attend to patients within the bore of the scanner, anesthesia providers are at significant risk of experiencing vertigo.3,5,8  Clinical experience suggests that the symptoms are transient and there is no evidence of long-term sequelae. Nonetheless, intense vertigo can be a debilitating experience that may have a profound impact on a practitioner’s ability to safely care for a patient in the MRI. Furthermore, there are data to suggest that the exposure to MRI may adversely affect hand–eye coordination and even cognitive performance.9 
Currently, there are no regulations for occupational exposure to MRI for healthcare workers in the United States. Guidelines published in 2009 (and updated in 2014) by the International Commission on Non-Ionizing Radiation Protection suggest limiting the change in magnetic flux density (magnetic field) to 2 Tesla for any 3-s period, largely because of concerns about vertigo and nausea.10  Exposure to static magnetic fields of up to 8 Tesla can be justified in controlled environments with appropriate work practices implemented to minimize the motion-related sensory phenomena. These guidelines assume that a clinician in the MRI environment can control his or her distance from the scanner as well as the speed of motion within the MRI room. However, it is easy to imagine an airway emergency occurring within the bore of a 3-Tesla or 7-Tesla MRI scanner, during which there would be little the anesthesia provider could do to limit his or her exposure to a rapidly changing magnetic field.
Magnetic resonance imaging–induced vertigo in anesthesia providers may become more common as the strength of MRI scanners increases. We think that education and prevention regarding this problem are imperative. Anesthesia providers should be instructed to stay as far away from the scanner as possible while still providing safe patient care. When possible, clinicians should avoid leaning directly into the bore of the MRI scanner. Rapid movements, including both linear translation and head rotation, should be avoided. Finally, back-up personnel should be available in the event that a provider experiences intense vertigo that impairs his or her ability to safely care for patients. It is our hope that future revisions of the Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging will address these concerns.
Competing Interests
The authors declare no competing interests.
Andrew Gorlin, M.D., Joseph M. Hoxworth, M.D., Jeff Mueller, M.D. Mayo Clinic Arizona, Phoenix, Arizona (A.G.). gorlin.andrew@mayo.edu
References
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