title: The onset location of multiple sclerosis predicts the location of subsequent relapses.
abstract: BACKGROUND
  Demyelinating events in relapsing-remitting multiple sclerosis (RRMS) can involve several locations in the central nervous system. We sought to determine if initial clinical demyelinating event (IDE) location predicts subsequent clinical relapse locations in early RRMS.
  
  
  METHODS
  We identified all RRMS patients from two large MS clinics who were seen within 1 year of disease onset. Logistic regression was performed with the outcome defined as the second or third exacerbation location and the predictor defined as IDE+/-second event location.
  
  
  RESULTS
  195 patients with at least two clinical exacerbations were identified. There was an increased odds of a patient's second relapse occurring in the spinal cord if the IDE was in the spinal cord (odds ratio (OR) = 3.79, 95% CI 2.06 to 7.00, p<0.001). There was more than a sixfold increase in the odds of a patient's second relapse occurring in the optic nerve if the IDE was in the optic nerve (OR = 6.18, 95% CI 2.90 to 13.18, p<0.001). These associations remained similar after adjusting for treatment and patient characteristics. If the IDE and second event were both in the same location (spinal cord, optic nerve or brainstem/cerebellum), the third event was likely to remain in that location.
  
  
  CONCLUSIONS
  Patients with RRMS have relatively localised clinical relapses. It remains to be determined if genetic or biological processes are responsible for this pattern.
authors.affiliation: Department of Neurology, University of California, Multiple Sclerosis Center, San Francisco, CA 94117, USA. ellen.mowry@ucsf.edu
authors.forename: E M
authors.initials: EM
authors.lastname: Mowry
authors.forename: S
authors.initials: S
authors.lastname: Deen
authors.forename: I
authors.initials: I
authors.lastname: Malikova
authors.forename: J
authors.initials: J
authors.lastname: Pelletier
authors.forename: P
authors.initials: P
authors.lastname: Bacchetti
authors.forename: E
authors.initials: E
authors.lastname: Waubant
mesh_terms: D000328:Adult; D017668:Age of Onset; D001921:Brain / Q000473:pathology*; D001933:Brain Stem / Q000473:pathology; D002531:Cerebellum / Q000473:pathology; D015331:Cohort Studies; D003711:Demyelinating Diseases / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology* / Q000628:therapy; D016017:Odds Ratio; D009900:Optic Nerve / Q000473:pathology; D011446:Prospective Studies; D012008:Recurrence; D013116:Spinal Cord / Q000473:pathology