title: Silent cerebral events in asymptomatic carotid stenosis.
abstract: BACKGROUND
  Approximately 20% of strokes are attributable to carotid stenosis. However, the number of asymptomatic patients needed to prevent one stroke or death with endarterectomy is high at 17 to 32. There is a clear need to identify asymptomatic individuals at high risk of developing future ischemic events to improve the cost-effectiveness of surgery. Our aim was to examine the evidence for subclinical microembolization and silent brain infarction in the prediction of stroke in asymptomatic carotid stenosis using transcranial Doppler (TCD), computed tomography (CT), and magnetic resonance imaging (MRI).
  
  
  METHODS
  The review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Articles regarding humans between 1966 and 2010 were identified through systematic searches of Pubmed, MEDLINE, and EMBASE electronic databases using a predetermined search algorithm.
  
  
  RESULTS
  Fifty-eight full text articles met the inclusion criteria. A median of 28% of microemboli positive patients experienced a stroke or transient ischemic attack during follow-up compared with 2% of microemboli negative patients (P = .001). The same was true for the end point of stroke alone with a median of 10% of microemboli positive patients experiencing a stroke vs 1% of microemboli negative patients (P = .004). A specific pattern of silent CT infarctions was related to future stroke risk (odds ratio [OR] = 4.6; confidence interval [CI] = 3.0-7.2; P < .0001). There are no prospective MRI studies linking silent infarction and stroke risk.
  
  
  CONCLUSIONS
  There is level 1 evidence for the use of TCD to detect microembolization as a risk stratification tool. However, this technique requires further investigation as a stroke prevention tool and would be complemented by improvements in carotid plaque imaging.
authors: Academic Section of Vascular Surgery, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
authors: Gayani
authors: G
authors: Jayasooriya
authors: Ankur
authors: A
authors: Thapar
authors: Joseph
authors: J
authors: Shalhoub
authors: Alun H
authors: AH
authors: Davies
mesh_terms: D058070:Asymptomatic Diseases; D016893:Carotid Stenosis / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D002533:Cerebral Angiography / Q000379:methods; D002544:Cerebral Infarction / Q000175:diagnosis / Q000209:etiology; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000209:etiology* / Q000517:prevention & control; D016894:Endarterectomy, Carotid; D019317:Evidence-Based Medicine; D006801:Humans; D020766:Intracranial Embolism / Q000175:diagnosis / Q000209:etiology; D018810:Magnetic Resonance Angiography; D018579:Patient Selection; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis / Q000209:etiology; D014057:Tomography, X-Ray Computed; D017585:Ultrasonography, Doppler, Transcranial