MRI Magnetic Field Stimulates Rotational Sensors of the Brain

Current Biology, 22 September 2011
Copyright © 2011 Elsevier Ltd All rights reserved.
10.1016/j.cub.2011.08.029

Authors

Dale C. Roberts,Vincenzo Marcelli,Joseph S. Gillen,John P. Carey,Charles C. Della Santina,David S. ZeeSee Affiliations

• Highlights
• All subjects in an MRI machine develop a robust nystagmus and often a sense of motion
• Nystagmus strength depends on static field strength, not motion through the field
• Horizontal nystagmus direction depends on head pitch angle and MRI field polarity
• Modeling suggests that MRI nystagmus is due to Lorentz forces pushing on the cupula

Summary

Vertigo in and around magnetic resonance imaging (MRI) machines has been noted for years [1,2]. Several mechanisms have been suggested to explain these sensations [3,4], yet without direct, objective measures, the cause is unknown. We found that all of our healthy human subjects developed a robust nystagmus while simply lying in the static magnetic field of an MRI machine. Patients lacking labyrinthine function did not. We use the pattern of eye movements as a measure of vestibular stimulation to show that the stimulation is static (continuous, proportional to static magnetic field strength, requiring neither head movement nor dynamic change in magnetic field strength) and directional (sensitive to magnetic field polarity and head orientation). Our calculations and geometric model suggest that magnetic vestibular stimulation (MVS) derives from a Lorentz force resulting from interaction between the magnetic field and naturally occurring ionic currents in the labyrinthine endolymph fluid. This force pushes on the semicircular canal cupula, leading to nystagmus. We emphasize that the unique, dual role of endolymph in the delivery of both ionic current and fluid pressure, coupled with the cupula's function as a pressure sensor, makes magnetic-field-induced nystagmus and vertigo possible. Such effects could confound functional MRI studies of brain behavior, including resting-state brain activity.

Association between Type 1 Diabetes Mellitus and Deposits in the Semicircular Canals

Otolaryngology - Head and Neck Surgery (May 2011)

Yoda S, Cureoglu S, Yildirim-Baylan M, Morita N, Fukushima H, Harada T, Paparella MM

Objective. To compare the prevalence of cupular and free-floating deposits in the semicircular canals between temporal bones of type 1 diabetes mellitus patients and normal controls. Study Design. Case-control histopathologic human temporal bone study. Setting. Otopathology laboratory in a tertiary academic medical center. 

Subjects and Methods. Twenty-eight temporal bones from 14 patients with type 1 diabetes mellitus and 56 normal temporal bones from 28 age-matched individuals were histopathologically examined. The cupula and lumina of the semicircular canals were examined for evidence of deposits. 

Results. The prevalence of cupular and free-floating deposits in the lateral and posterior semicircular canals was significantly higher in type 1 diabetes mellitus patients compared with normal temporal bones (lateral, cupular deposits, odds ratio [OR], 5.47; 95% confidence interval [CI], 1.43 to 21.02; free-floating deposits, OR, 8.25; 95% CI, 2.42 to 27.85; posterior, cupular deposits, OR, 41.73; 95% CI, 5.96 to 275.50; free-floating deposits, OR, 7.44; 95% CI, 1.91 to 28.53). The 

prevalence of these deposits was associated with the duration of disease rather than with aging.


Conclusion. The findings suggest that type 1 diabetes mellitus is associated with cupular and free-floating deposits in the semicircular canals. The patients with type 1 diabetes mellitus with a longer duration of disease have an increased probability of suffering from benign paroxysmal positional vertigo.

Association between Type 1 Diabetes Mellitus and Deposits in the Semicircular Canals

Otolaryngology - Head and Neck Surgery (May 2011)

Yoda S, Cureoglu S, Yildirim-Baylan M, Morita N, Fukushima H, Harada T, Paparella MM

Objective. To compare the prevalence of cupular and free-floating deposits in the semicircular canals between temporal bones of type 1 diabetes mellitus patients and normal controls. Study Design. Case-control histopathologic human temporal bone study. Setting. Otopathology laboratory in a tertiary academic medical center. 

Subjects and Methods. Twenty-eight temporal bones from 14 patients with type 1 diabetes mellitus and 56 normal temporal bones from 28 age-matched individuals were histopathologically examined. The cupula and lumina of the semicircular canals were examined for evidence of deposits. 

Results. The prevalence of cupular and free-floating deposits in the lateral and posterior semicircular canals was significantly higher in type 1 diabetes mellitus patients compared with normal temporal bones (lateral, cupular deposits, odds ratio [OR], 5.47; 95% confidence interval [CI], 1.43 to 21.02; free-floating deposits, OR, 8.25; 95% CI, 2.42 to 27.85; posterior, cupular deposits, OR, 41.73; 95% CI, 5.96 to 275.50; free-floating deposits, OR, 7.44; 95% CI, 1.91 to 28.53). The 

prevalence of these deposits was associated with the duration of disease rather than with aging. Conclusion. The findings suggest that type 1 diabetes mellitus is associated with cupular and free-floating deposits in the semicircular canals. The patients with type 1 diabetes mellitus with a longer duration of disease have an increased probability of suffering from benign paroxysmal positional vertigo.

Vestibular-Evoked Myogenic Potentials in Migrainous Vertigo

Otolaryngology - Head and Neck Surgery 144 (2), 284-287 (Feb 2011)

Hong SM, Kim SK, Park CH, Lee JH

Objective. Patients with migraine headaches have a high prevalence of episodic vertigo, and several studies support the clinical association of migraine and vertigo. Various tests have been conducted in patients with migrainous vertigo; however, only a few studies have been reported on otolith function. The aim of the present study was to increase the understanding of migrainous vertigo pathophysiology by assessing the sacculocollic pathway in patients with migrainous vertigo using vestibular-evoked myogenic potentials testing (VEMPs). Study Design. Prospective study. 
Setting. Tertiary referral center. Subjects and Methods. VEMP testing was performed in 30 patients with migrainous vertigo and 31 healthy volunteers using 90- and 100-dB tone-pip stimuli. We compared hearing, p13 and n23 latency, VEMP asymmetry, and VEMP formation rate between the patient and control groups. Results. No between-group difference was observed in p13 and n23 latency or VEMP asymmetry. The rate of normal VEMP wave formation in both ears was significantly lower in the patient group compared with that of the control group in response to the 90-dB stimulus. Furthermore, VEMP wave formation was absent in both ears at 100 dB in significantly more patients than in control subjects. 


Conclusion. The results indicate that patients with migrainous vertigo show abnormal VEMP findings, suggesting that migrainous vertigo might have a lesion at the sacculocollic pathway.