title: Parallel changes in structural and functional measures of optic nerve myelination after optic neuritis.
abstract: BACKGROUND
  Visual evoked potential (VEP) latency prolongation and optic nerve lesion length after acute optic neuritis (ON) corresponds to the degree of demyelination, while subsequent recovery of latency may represent optic nerve remyelination. We aimed to investigate the relationship between multifocal VEP (mfVEP) latency and optic nerve lesion length after acute ON.
  
  
  METHODS
  Thirty acute ON patients were studied at 1, 3, 6 and 12 months using mfVEP and at 1 and 12 months with optic nerve MRI. LogMAR and low contrast visual acuity were documented. By one month, the mfVEP amplitude had recovered sufficiently for latency to be measured in 23 (76.7%) patients with seven patients having no recordable mfVEP in more than 66% of segments in at least one test. Only data from these 23 patients was analysed further.
  
  
  RESULTS
  Both latency and lesion length showed significant recovery during the follow-up period. Lesion length and mfVEP latency were highly correlated at 1 (r = 0.94, p = <0.0001) and 12 months (r = 0.75, p < 0.001). Both measures demonstrated a similar trend of recovery. Speed of latency recovery was faster in the early follow-up period while lesion length shortening remained relatively constant. At 1 month, latency delay was worse by 1.76 ms for additional 1mm of lesion length while at 12 months, 1mm of lesion length accounted for 1.94 ms of latency delay.
  
  
  CONCLUSIONS
  A strong association between two putative measures of demyelination in early and chronic ON was found. Parallel recovery of both measures could reflect optic nerve remyelination.
authors.affiliation: Centre for Neuroscience, University of Melbourne, Melbourne, Australia; Department of Neurology, Royal Melbourne Hospital, Melbourne, Australia; Department of Medicine, University of Melbourne, Melbourne, Australia.
authors.forename: Anneke
authors.initials: A
authors.lastname: van der Walt
authors.affiliation: Centre for Neuroscience, University of Melbourne, Melbourne, Australia.
authors.forename: Scott
authors.initials: S
authors.lastname: Kolbe
authors.affiliation: Department of Radiology, Royal Melbourne Hospital, Melbourne, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Mitchell
authors.affiliation: Centre for Neuroscience, University of Melbourne, Melbourne, Australia.
authors.forename: Yejun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Neurology, Royal Melbourne Hospital, Melbourne, Australia; Department of Medicine, University of Melbourne, Melbourne, Australia; Department of Neurology, Box Hill Hospital, Melbourne, Australia.
authors.forename: Helmut
authors.initials: H
authors.lastname: Butzkueven
authors.affiliation: Monash University, Melbourne, Australia.
authors.forename: Gary
authors.initials: G
authors.lastname: Egan
authors.affiliation: Department of Neurology, Concord Hospital, Sydney, Australia.
authors.forename: Con
authors.initials: C
authors.lastname: Yiannikas
authors.affiliation: Department of Ophthalmology, Save Sight Institute, University of Sydney, Sydney, Australia; Australian School of Advanced Medicine, Macquarie University, Sydney, Australia.
authors.forename: Stuart
authors.initials: S
authors.lastname: Graham
authors.affiliation: Centre for Neuroscience, University of Melbourne, Melbourne, Australia; Department of Neurology, Royal Melbourne Hospital, Melbourne, Australia.
authors.forename: Trevor
authors.initials: T
authors.lastname: Kilpatrick
authors.affiliation: Department of Ophthalmology, Save Sight Institute, University of Sydney, Sydney, Australia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Klistorner
mesh_terms: D000328:Adult; D003711:Demyelinating Diseases / Q000473:pathology* / Q000503:physiopathology; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009900:Optic Nerve / Q000503:physiopathology*; D009902:Optic Neuritis / Q000473:pathology* / Q000503:physiopathology; D014792:Visual Acuity