title: Upper Respiratory Infections and MRI Activity in Relapsing-Remitting Multiple Sclerosis.
abstract: BACKGROUND
  Although clinical reports have suggested a relationship between systemic infections and multiple sclerosis (MS) relapses, MRI evidence supporting an association is conflicting. Here we evaluated the temporal relationship between upper respiratory infections (URIs) and MRI activity in relapsing-remitting (RR) MS.
  
  
  METHODS
  We combined individual data on URI with data on active lesions in pre-scheduled MRI examinations performed every 4 weeks for 28 weeks in 69 patients. A 4-week at-risk (AR) period started, by definition, 1 week before the onset of a URI. We recorded the relationship between the number of active lesions in each MRI with (1) the number of days of AR time in the immediately preceding 4-week period and (2) the number of days passed since the onset of a preceding URI.
  
  
  RESULTS
  Average MRI lesions/day showed no difference between AR (0.0764) and not-AR (0.0774) periods. The number of lesions in 483 pre-scheduled MRI examinations did not correlate with the AR proportion in the prior 4-week period (rho = -0.03), and time from URI onset did not correlate with lesion number on the next MRI examination (rho = 0.003).
  
  
  CONCLUSIONS
  The occurrence of a URI did not increase the risk of MRI activity evaluated in an adjacent 4-week window in RRMS.
authors: Section of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Maria
authors: M
authors: Kneider
authors: Vera
authors: V
authors: Lisovskaja
authors: Jan
authors: J
authors: Lycke
authors: Clas
authors: C
authors: Malmeström
authors: Johannes K
authors: JK
authors: Jakobsen
authors: Olle
authors: O
authors: Nerman
authors: Oluf
authors: O
authors: Andersen
mesh_terms: D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000453:epidemiology / Q000473:pathology*; D016032:Randomized Controlled Trials as Topic; D012141:Respiratory Tract Infections / Q000150:complications* / Q000453:epidemiology