title: Diffusion tensor imaging in acute optic neuropathies: predictor of clinical outcomes.
abstract: OBJECTIVE
  To evaluate directional diffusivities within the optic nerve in a first event of acute optic neuritis to determine whether decreased axial diffusivity (AD) would predict 6-month visual outcome and optic nerve integrity measures.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Academic multiple sclerosis center. Patients  Referred sample of 25 individuals who presented within 31 days after acute visual symptoms consistent with optic neuritis. Visits were scheduled at baseline, 2 weeks, and 1, 3, 6, and 12 months.
  
  
  METHODS
  Visual acuity, contrast sensitivity, visual evoked potentials (VEPs), and thickness of the retinal nerve fiber layer (RNFL).
  
  
  RESULTS
  An incomplete 6-month visual recovery was associated with a lower baseline AD (1.50 μm(2)/ms [95% confidence interval {CI}, 1.36-1.64 μm(2)/ms for incomplete recovery vs 1.75 μm(2)/ms [95% CI, 1.67-1.83 μm(2)/ms] for complete recovery). Odds of complete recovery decreased by 53% (95% CI, 27%-70%) for every 0.1-unit decrease in baseline AD. A lower baseline AD correlated with worse 6-month visual outcomes in visual acuity (r = 0.40, P = .03), contrast sensitivity (r = 0.41, P = .02), VEP amplitude (r = 0.55, P < .01), VEP latency (r = -0.38, P = .04), and RNFL thickness (r = 0.53, P = .02). Radial diffusivity increased between months 1 and 3 to become higher in those with incomplete recovery at 12 months than in those with complete recovery (1.45 μm(2)/ms [95% CI, 1.31-1.59 μm(2)/ms] vs 1.19 μm(2)/ms [95% CI, 1.10-1.28 μm(2)/ms]).
  
  
  CONCLUSIONS
  Decreased AD in acute optic neuritis was associated with a worse 6-month visual outcome and correlated with VEP and RNFL measures of axon and myelin injury. Axial diffusivity may serve as a marker of axon injury in acute white matter injury.
authors.affiliation: Department of Neurology, Washington University in St Louis, Campus Box 8111, 660 S Euclid Ave, St Louis, MO 63110, USA. naismithr@neuro.wustl.edu
authors.forename: Robert T
authors.initials: RT
authors.lastname: Naismith
authors.forename: Junqian
authors.initials: J
authors.lastname: Xu
authors.forename: Nhial T
authors.initials: NT
authors.lastname: Tutlam
authors.forename: Samantha
authors.initials: S
authors.lastname: Lancia
authors.forename: Kathryn
authors.initials: K
authors.lastname: Trinkaus
authors.forename: Sheng-Kwei
authors.initials: SK
authors.lastname: Song
authors.forename: Anne H
authors.initials: AH
authors.lastname: Cross
mesh_terms: D000208:Acute Disease; D000328:Adult; D056324:Diffusion Tensor Imaging; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D011237:Predictive Value of Tests; D020127:Recovery of Function; D012720:Severity of Illness Index; D013997:Time Factors; D014787:Vision Tests; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult