title: High rate of magnetic resonance imaging stroke recurrence in cryptogenic transient ischemic attack and minor stroke patients.
abstract: OBJECTIVE
  Cryptogenic stroke is common in patients with transient ischemic attack (TIA) and minor stroke. It is likely that the imaging recurrence risk is higher than the clinical recurrence rate. We sought to determine the rate of clinical and radiographic stroke recurrence in a population of cryptogenic TIA and minor stroke.
  
  
  METHODS
  Patients with TIA/minor stroke (National Institutes of Health Stroke Scale score≤3) were prospectively enrolled and imaged within 24 hours of symptom onset as part of 2 cohorts. Patients were assessed at 3 months to document any clinical recurrence and underwent repeat magnetic resonance imaging (MRI) at either 30 or 90 days. Stroke mechanism was categorized as cryptogenic after standard etiologic work-up was completed and was negative. Follow-up MRI was assessed for any new lesions in comparison with baseline imaging.
  
  
  RESULTS
  Three hundred thirty-three of 693 (48%) patients had cryptogenic stroke. Of these cryptogenic patients, 207 (62%) had follow-up imaging. At 30-day MRI follow-up, 6.6% (5/76) had new lesions (3 in a remote arterial territory). At 90-day MRI follow-up, 14.5% (19/131) had new lesions (9 in a remote arterial territory). Clinical recurrent stroke was seen in 1.2% (4/333) of patients within 90 days.
  
  
  CONCLUSIONS
  Cryptogenic etiology is common in a TIA/minor stroke population. This population shows a high rate of silent radiographic recurrence, suggesting active disease. Use of MRI as a surrogate marker of disease activity is 1 potential way of assessing efficacy of new treatments in this population with reduced sample size.
authors.affiliation: Department of Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, and Foothills Hospital, C1261, 1403 29 St NW, Calgary, AB, T2N 2T9, Canada.
authors.forename: Simerpreet
authors.initials: S
authors.lastname: Bal
authors.forename: Shiel K
authors.initials: SK
authors.lastname: Patel
authors.forename: Mohammed
authors.initials: M
authors.lastname: Almekhlafi
authors.forename: Jayesh
authors.initials: J
authors.lastname: Modi
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
authors.forename: Shelagh B
authors.initials: SB
authors.lastname: Coutts
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012008:Recurrence; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000453:epidemiology* / Q000473:pathology*