title: Circulating microemboli in 33 patients with intracranial arterial stenosis.
abstract: BACKGROUND
  Intracranial arterial stenosis is a rare cause of stroke in Caucasians. Detection of clinically silent circulating microemboli by transcranial Doppler sonography is now widely investigated in patients with carotid artery disease in the hope to identify patients at increased risk for stroke.
  
  
  METHODS
  In 33 patients with intracranial internal carotid (n = 12), middle cerebral (n = 18), posterior cerebral (n = 2), or basilar artery stenosis (n = 1), we performed a 1-hour microembolus detection downstream to the stenosis in the middle or in the posterior cerebral artery, respectively. The stenosis was assessed by transcranial Doppler and duplex ultrasound. 18 patients had been symptomatic in the dependent territory.
  
  
  RESULTS
  Five patients with ischaemic symptoms within the last 8 days and with a peak systolic flow velocity of > or =210 cm/s in the stenosis showed microembolic signals at a rate of 3-25 events/h, despite effective anticoagulation. All these 5 patients had a lesion pattern on cranial CT or MRI scan suggesting embolic origin. All the asymptomatic patients (n = 15) and all the patients with a peak systolic intrastenostic velocity of 160 to <210 cm/s (n = 13) did not show microembolic signals at all.
  
  
  CONCLUSIONS
  Microembolic signals occur in recently symptomatic patients with high-grade intracranial arterial stenosis indicated by a sonographically measured stenotic peak flow velocity of > or =210 cm/s. Therapeutic anticoagulation was not sufficient to suppress microemboli formation.
authors.affiliation: Department of Neurology, University of Münster, Germany.
authors.forename: Dirk W
authors.initials: DW
authors.lastname: Droste
authors.forename: Katja
authors.initials: K
authors.lastname: Junker
authors.forename: Tjark
authors.initials: T
authors.lastname: Hansberg
authors.forename: Ralf
authors.initials: R
authors.lastname: Dittrich
authors.forename: Martin
authors.initials: M
authors.lastname: Ritter
authors.forename: E Bernd
authors.initials: EB
authors.lastname: Ringelstein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D020520:Brain Infarction / Q000175:diagnosis / Q000453:epidemiology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D020765:Intracranial Arterial Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D020766:Intracranial Embolism / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D018616:Ultrasonography, Doppler, Duplex; D017585:Ultrasonography, Doppler, Transcranial