title: Cerebral microembolism in patients with retinal ischemia.
abstract: OBJECTIVE
  We investigated the frequency of cerebral microembolism detected by transcranial Doppler ultrasonography in patients with clinical evidence of retinal ischemia, including transient monocular blindness, central and branch retinal artery infarction, and ischemic oculopathy, and assessed its correlation with carotid artery stenosis.
  
  
  METHODS
  Records of 331 consecutive patients examined during a 47-month period at the Neurovascular Laboratory were reviewed. Of the original 453 intracranial arteries, 186 middle cerebral arteries (MCAs) satisfied qualifying criteria that excluded patients with cardiac embolic sources. Forty-five MCAs ipsilateral to the symptomatic eye constituted the study group. The control group consisted of 141 asymptomatic MCAs. Microembolus detection studies were performed on transcranial Doppler instruments equipped with special software, and the degree of carotid artery stenosis was measured by cerebral or MR angiography or by color duplex studies.
  
  
  RESULTS
  Microembolism was detected in 40.0% of study MCAs and 9.2% of controls (P < 0.001). In the study group, microembolic signals were detected in 61.9% of MCAs tested within a week of symptom onset and 20.8% of those tested afterward (P < 0.001). Severe (> or = 70%) carotid stenosis or occlusion was more frequent in the study group (P < 0.001). Microembolic signals were detected in 25.3% and 11.2%, respectively, of MCAs distal to carotid arteries with 70% to 100% and 0% to 69% stenosis (P = 0.013).
  
  
  CONCLUSIONS
  In patients without cardiac embolic sources, cerebral microembolism is frequently present on the side of retinal ischemia, particularly during the week after onset of symptoms. It is often associated with severe stenosis or occlusion of the ipsilateral carotid artery.
authors.affiliation: Department of Neurology, Boston University School of Medicine, Mass., USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Wijman
authors.forename: V L
authors.initials: VL
authors.lastname: Babikian
authors.forename: I C
authors.initials: IC
authors.lastname: Matjucha
authors.forename: B
authors.initials: B
authors.lastname: Koleini
authors.forename: C
authors.initials: C
authors.lastname: Hyde
authors.forename: M R
authors.initials: MR
authors.lastname: Winter
authors.forename: V E
authors.initials: VE
authors.lastname: Pochay
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000453:epidemiology; D016893:Carotid Stenosis / Q000503:physiopathology; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D005123:Eye / Q000098:blood supply*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D015994:Incidence; D002542:Intracranial Embolism and Thrombosis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D012160:Retina / Q000503:physiopathology*; D012161:Retinal Artery / Q000503:physiopathology; D012189:Retrospective Studies; D017585:Ultrasonography, Doppler, Transcranial; D015349:Vision, Monocular