title: Normal diffusion-weighted MRI during stroke-like deficits.
abstract: BACKGROUND
  Diffusion-weighted MRI (DWI) represents a major advance in the early diagnosis of acute ischemic stroke. When abnormal in patients with stroke-like deficit, DWI usually establishes the presence and location of ischemic brain injury. However, this is not always the case.
  
  
  OBJECTIVE
  To investigate patients with stroke-like deficits occurring without DWI abnormalities in brain regions clinically suspected to be responsible.
  
  
  METHODS
  We identified 27 of 782 consecutive patients scanned when stroke-like neurologic deficits were still present and who had normal DWI in the brain region(s) clinically implicated. Based on all the clinical and radiologic data, we attempted to arrive at a pathophysiologic diagnosis in each.
  
  
  RESULTS
  Best final diagnosis was a stroke mimic in 37% and a cerebral ischemic event in 63%. Stroke mimics (10 patients) included migraine, seizures, functional disorder, transient global amnesia, and brain tumor. The remaining patients were considered to have had cerebral ischemic events: lacunar syndrome (7 patients; 3 with infarcts demonstrated subsequently) and hemispheric cortical syndrome (10 patients; 5 with TIA, 2 with prolonged reversible deficits, 3 with infarction on follow-up imaging). In each of the latter three patients, the regions destined to infarct showed decreased perfusion on the initial hemodynamically weighted MRI (HWI).
  
  
  CONCLUSIONS
  Normal DWI in patients with stroke-like deficits should stimulate a search for nonischemic cause of symptoms. However, more than one-half of such patients have an ischemic cause as the best clinical diagnosis. Small brainstem lacunar infarctions may escape detection. Concomitant HWI can identify some patients with brain ischemia that is symptomatic but not yet to the stage of causing DWI abnormality.
authors.affiliation: Stroke Service of the Neurology Department, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA.
authors.forename: H
authors.initials: H
authors.lastname: Ay
authors.forename: F S
authors.initials: FS
authors.lastname: Buonanno
authors.forename: G
authors.initials: G
authors.lastname: Rordorf
authors.forename: P W
authors.initials: PW
authors.lastname: Schaefer
authors.forename: L H
authors.initials: LH
authors.lastname: Schwamm
authors.forename: O
authors.initials: O
authors.lastname: Wu
authors.forename: R G
authors.initials: RG
authors.lastname: Gonzalez
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: G A
authors.initials: GA
authors.lastname: Sorensen
authors.forename: W J
authors.initials: WJ
authors.lastname: Koroshetz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology*; D002561:Cerebrovascular Disorders / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged