title: Corticospinal tract integrity measured using transcranial magnetic stimulation and magnetic resonance imaging in neuromyelitis optica and multiple sclerosis.
abstract: BACKGROUND
  Both multiple sclerosis (MS) and neuromyelitis optica (NMO) can present with transverse myelitis; however, NMO symptoms are usually more severe and may present with more extensive axonal loss. Transcranial magnetic stimulation (TMS)-based input-output recruitment curves can quantitatively assess the excitability of corticospinal tract pathways and myelin water imaging can quantify the amount of myelin within this same pathway.
  
  
  OBJECTIVE
  To compare differential effects of MS and NMO on TMS recruitment curves and myelin water imaging.
  
  
  METHODS
  Ten healthy controls, 10 individuals with MS and 10 individuals with NMO completed clinical assessments, a TMS assessment and magnetic resonance imaging scan to measure recruitment curves and myelin water fraction in the corticospinal tract.
  
  
  RESULTS
  Individuals with NMO had lower recruitment curve slopes (mean 13.6±6 μV/%) than MS (23.6±11 μV/%) and controls (21.9±9 μV/%, analysis of variance (ANOVA) P=0.05). Corticospinal tract myelin water fraction was lower in individuals with NMO (mean 0.17±0.02) compared to MS (0.19±0.02) and controls (0.20±0.02, ANOVA P=0.0006).
  
  
  CONCLUSIONS
  Corticospinal pathway damage in individuals with NMO was evident by reduced recruitment curve slope and lower myelin water fraction. These specific measures of corticospinal function and structure may be used to obtain a better understanding and monitor brain injury caused by inflammatory central nervous system disorders.
authors.affiliation: Department of Medicine, University of British Columbia, Canada.
authors.forename: Praveena
authors.initials: P
authors.lastname: Manogaran
authors.affiliation: Department of Radiology, University of British Columbia, Canada.
authors.forename: Irene
authors.initials: I
authors.lastname: Vavasour
authors.affiliation: Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, USA/Department of Pediatrics, University of British Columbia, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Borich
authors.affiliation: Department of Medicine, University of British Columbia, Canada.
authors.forename: Shannon H
authors.initials: SH
authors.lastname: Kolind
authors.affiliation: Department of Medicine, University of British Columbia, Canada.
authors.forename: Alex P
authors.initials: AP
authors.lastname: Lange
authors.affiliation: Department of Radiology, University of British Columbia, Canada.
authors.forename: Alexander
authors.initials: A
authors.lastname: Rauscher
authors.affiliation: Department of Physical Therapy, Brain Behaviour Laboratory, Canada.
authors.forename: Lara
authors.initials: L
authors.lastname: Boyd
authors.affiliation: Department of Radiology, University of British Columbia, Canada.
authors.forename: David Kb
authors.initials: DK
authors.lastname: Li
authors.affiliation: Department of Medicine, University of British Columbia, Canada t.traboulsee@ubc.ca.
authors.forename: Anthony
authors.initials: A
authors.lastname: Traboulsee
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology* / Q000503:physiopathology*; D009471:Neuromyelitis Optica / Q000473:pathology* / Q000503:physiopathology*; D011712:Pyramidal Tracts / Q000473:pathology* / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: Multiple sclerosis; corticospinal tract; magnetic resonance imaging; neuromyelitis optica; recruitment curve; transcranial magnetic stimulation