Qualitative and quantitative assessment of magnetic vestibular stimulation in humans
Article type: Research Article
Authors: Dewey, Rebecca S.a; b; c; * | Gomez, Rachelb; d; e | Degg, Chrisf | Baguley, David M.b; c; g | Glover, Paul M.a
Affiliations: [a] Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, UK | [b] National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Nottingham, UK | [c] Hearing Sciences, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, UK | [d] Nottingham Clinical Trials Unit, School of Medicine, University of Nottingham, UK | [e] Faculty of Life and Health Sciences, De Montfort University, Leicester, UK | [f] Medical Physics and Clinical Engineering, Nottingham University Hospitals NHS Trust, UK | [g] Nottingham Audiology Services, Nottingham University Hospitals NHS Trust, UK
Correspondence: [*] Corresponding author: Rebecca Dewey; National Institute for Health Research (NIHR) Nottingham Biomedical Research Centre, Ropewalk House, 113 The Ropewalk, Nottingham, NG1 5DU, UK. Tel.: +44 7762187556; E-mail: rebecca.dewey@physics.org.
Abstract: The sensation of phantom motion or exhibition of bodily sway is often reported in the proximity of an MR scanner. It is proposed that the magnetic field stimulates the vestibular system. There are a number of possible mechanisms responsible, and the relative contributions of susceptibility on the otolithic receptors and the Lorentz force on the cupulae have not yet been explored. This exploratory study aims to investigate the impact of being in the proximity of a 7.0 T MR scanner. The modified clinical test of sensory interaction on balance (mCTSIB) was used to qualitatively ascertain whether or not healthy control subjects who passed the mCTSIB in normal conditions 1) experienced subjective sensations of dizziness, vertigo or of leaning or shifting in gravity when in the magnetic field and 2) exhibited visibly increased bodily sway whilst in the magnetic field compared to outside the magnetic field. Condition IV of the mCTSIB was video recorded outside and inside the magnetic field, providing a semi-quantitative measure of sway. For condition IV of the mCTSIB (visual and proprioceptive cues compromised), all seven locations/orientations around the scanner yielded significantly more sway than at baseline (p < 0.01 FDR). A Student’s t-test comparing the RMS velocity of a motion marker on the upper arm during mCTSIB condition IV showed a significant increase in the amount of motion exhibited in the field (T = 2.59; d.f. = 9; p = 0.029) compared to outside the field. This initial study using qualitative measures of sway demonstrates that there is evidence for MR-naïve individuals exhibiting greater sway while performing the mCTSIB in the magnetic field compared to outside the field. Directional polarity of sway was not significant. Future studies of vestibular stimulation by magnetic fields would benefit from the development of a sensitive, objective measure of balance function, which can be performed inside a magnetic field.
Keywords: Vestibular, magnetic resonance imaging
DOI: 10.3233/VES-201538
Journal: Journal of Vestibular Research, vol. 30, no. 6, pp. 353-361, 2020
