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Article
Impact of non-brain anatomy and coil orientation on inter- and intra-subject variability in TMS at midline
Clinical Neurophysiology
  • Erik G. Lee, Iowa State University and Harvard Medical School
  • Priyam Rastogi, Iowa State University
  • Ravi L. Hadimani, Iowa State University and Virginia Commonwealth University
  • David C. Jiles, Iowa State University
  • Joan A. Camprodon, Harvard Medical School
Document Type
Article
Publication Version
Accepted Manuscript
Publication Date
5-12-2018
DOI
10.1016/j.clinph.2018.04.749
Abstract
Objective: To investigate inter-subject variability with respect to cerebrospinal fluid thickness and brain-scalp distance, and to investigate intra-subject variability with different coil orientations. Methods: Simulations of the induced electric field (E-Field) using a figure-8 coil over the vertex were conducted on 50 unique head models, and varying orientations on 25 models. Metrics exploring stimulation intensity, spread, and localization were used to describe inter-subject variability and effects of non-brain anatomy. Results: Both brain-scalp distance and CSF thickness were correlated with weaker stimulation intensity, and greater spread. Coil rotations show that for the dorsal portion of the stimulated brain, E-Field intensities are highest when the anterior-posterior axis of the coil is perpendicular to the longitudinal fissure, but highest for the medial portion of the stimulated brain when the coil is oriented parallel to the longitudinal fissure. Conclusions: Normal anatomical variation in healthy individuals leads to significant differences in the site of TMS, the intensity and the spread. These variables are generally neglected but could explain significant variability in basic and clinical studies. Significance: This is the first work to show how brain-scalp distance and cerebrospinal fluid thickness influence focality, and to show the disassociation between dorsal and medial TMS.
Comments

This is a manuscript of an article published as Lee, Erik G., P. Rastogi, R. L. Hadimani, D. C. Jiles, and Joan A. Camprodon. "Impact of non-brain anatomy and coil orientation on inter-and intra-subject variability in TMS at midline." Clinical Neurophysiology (2018). DOI: 10.1016/j.clinph.2018.04.749. Posted with permission.

Creative Commons License
Creative Commons Attribution-Noncommercial-No Derivative Works 4.0
Copyright Owner
International Federation of Clinical Neurophysiology
Language
en
File Format
application/pdf
Citation Information
Erik G. Lee, Priyam Rastogi, Ravi L. Hadimani, David C. Jiles, et al.. "Impact of non-brain anatomy and coil orientation on inter- and intra-subject variability in TMS at midline" Clinical Neurophysiology (2018)
Available at: http://works.bepress.com/rlhadimani/34/