title: Spinal cord diffusion-tensor imaging and motor-evoked potentials in multiple sclerosis patients: microstructural and functional asymmetry.
abstract: OBJECTIVE
  To assess possible association between intrinsic structural damage and clinical disability by correlating spinal cord diffusion-tensor (DT) imaging data with electrophysiological parameters in patients with a diagnosis of multiple sclerosis (MS).
  
  
  METHODS
  This study was approved by the local ethical committee according to the declaration of Helsinki and written informed consent was obtained. DT images and T1- and T2-weighted images of the spinal cord were acquired in 28 healthy volunteers and 41 MS patients. Fractional anisotropy (FA) and apparent diffusion coefficients were evaluated in normal-appearing white matter (NAWM) at the cervical level and were correlated with motor-evoked potentials (n = 34). Asymmetry index was calculated for FA values with corresponding left and right regions of interest as percentage of the absolute difference between these values relative to the sum of the respective FA values. Statistical analysis included Spearman rank correlations, Mann-Whitney test, and reliability analysis.
  
  
  RESULTS
  Healthy volunteers had low asymmetry index (1.5%-2.2%). In MS patients, structural abnormalities were reflected by asymmetric decrease of FA (asymmetry index: 3.6%; P = .15). Frequently asymmetrically affected among MS patients was left and right central motor conduction time (CMCT) to abductor digiti minimi muscle (ADMM) (asymmetry index, 15%-16%) and tibialis anterior muscle (TAM) (asymmetry index, 9.5%-14.1%). Statistically significant correlations of functional (ie, electrophysiological) and structural (ie, DT imaging) asymmetries were found (P = .005 for CMCT to ADMM; P = .007 for CMCT to TAM) for the cervical lateral funiculi, which comprise the crossed pyramidal tract. Interobserver reliability for DT imaging measurements was excellent (78%-87%).
  
  
  CONCLUSIONS
  DT imaging revealed asymmetric anatomic changes in spinal cord NAWM, which corresponded to asymmetric electrophysiological deficits for both arms and legs, and reflected a specific structure-function relationship in the human spinal cord.
authors.affiliation: Department of Neuroradiology, University Hospital Zürich, Frauenklinikstrasse 26, 8091 Zürich, Switzerland. janvonmeyenburg@bluewin.ch
authors.forename: Jan
authors.initials: J
authors.lastname: von Meyenburg
authors.forename: Bertram J
authors.initials: BJ
authors.lastname: Wilm
authors.forename: Anja
authors.initials: A
authors.lastname: Weck
authors.forename: Jens
authors.initials: J
authors.lastname: Petersen
authors.forename: Evelyn
authors.initials: E
authors.lastname: Gallus
authors.forename: Jan
authors.initials: J
authors.lastname: Mathys
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Schaetzle
authors.forename: Martin
authors.initials: M
authors.lastname: Schubert
authors.forename: Peter
authors.initials: P
authors.lastname: Boesiger
authors.forename: Kaspar
authors.initials: K
authors.lastname: von Meyenburg
authors.forename: Norbert
authors.initials: N
authors.lastname: Goebels
authors.forename: Spyros
authors.initials: S
authors.lastname: Kollias
mesh_terms: D000328:Adult; D016880:Anisotropy; D001132:Arm / Q000503:physiopathology; D016022:Case-Control Studies; D003287:Contrast Media; D056324:Diffusion Tensor Imaging / Q000379:methods*; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007866:Leg / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology* / Q000503:physiopathology*; D011446:Prospective Studies; D013116:Spinal Cord / Q000473:pathology* / Q000503:physiopathology*; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media