title: Real-time hemodynamic assessment of intracranial stenosis in a patient with orthostatic aphasia: potential applications of transcranial Doppler.
abstract: BACKGROUND
  Intracranial atherosclerotic stenosis is thought to be responsible for 8% of all ischemic stroke subtypes. Transcranial Doppler (TCD) ultrasonography allows for noninvasive and dynamic evaluation of the cerebral circulation within the circle of Willis. We present a case of recurrent, orthostatic transient ischemic attacks in which, using TCD, we were able to correlate dynamically between the orthostatic symptomatology and a significant drop in the mean flow velocity (MFV) across the stenotic middle cerebral artery (MCA) segment.
  
  
  METHODS
  A 56-year-old male presented with recurrent episodes of orthostatic right-sided weakness and expressive aphasia. Diagnostic TCD revealed a stenotic signal in the left internal carotid artery (ICA) siphon. Subsequent TCD monitoring of both MCAs demonstrated a significant orthostatic drop in MFV of the left MCA, which closely correlated with his symptoms. The cerebral angiogram confirmed a high-grade stenosis at the supraclinoid segment of the left ICA.
  
  
  CONCLUSIONS
  TCD is a useful, noninvasive, and dynamic tool for assessment of the intracranial circulation, and should be considered in the workup of patients with hypoperfusion cerebrovascular events.
authors.affiliation: Department of Neurology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Aladdin
authors.forename: Muhammad S
authors.initials: MS
authors.lastname: Hussain
authors.forename: Maher
authors.initials: M
authors.lastname: Saqqur
mesh_terms: D001783:Blood Flow Velocity; D002545:Brain Ischemia / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D003937:Diagnosis, Differential; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011187:Posture; D017585:Ultrasonography, Doppler, Transcranial