title: The significance of the cerebral collateral capacity in patients with carotid atheroma.
abstract: OBJECTIVE
  to identify the echodensity, stenosis of carotid plaques and cerebral collateral capacity that were associated with various ipsilateral presentations (retinal, cerebrovascular, asymptomatic).
  
  
  METHODS
  cross-sectional study.
  
  
  METHODS
  forty-four patients, with 44 plaques associated with various presentations, were studied.
  
  
  METHODS
  the duplex images of the plaques were analysed echomorphologically in a computer by means of Grey Scale Median (GSM) [hypoechoic (low GSM), hyperechoic (high GSM)]. The percentage (%) reduction of the mean velocity in the middle cerebral artery (PRMCA) on transcranial Doppler, during clamping in carotid endarterectomy, was evaluated to distinguish the competent cerebral collateral supply (low PRMCA) from the non-competent one (high PRMCA).
  
  
  RESULTS
  the retinal symptoms were associated with plaques of low median GSM (0), severe median stenosis (90%) and low median PRMCA (0.31) as contrasted with the cerebrovascular symptoms (17, 84%, 0.47, respectively) and asymptomatic status (32, 83%, 0.4, respectively) [(p =0.038 (GSM), p =0.67 (stenosis), p=0.15 (PRMCA)]. The retinal and the cerebrovascular symptoms were distinct in terms of PRMCA (p=0.045).
  
  
  CONCLUSIONS
  the retinal symptoms were produced by hypoechoic and possibly embologenic plaques, whereas the cerebrovascular ones possibly by the combination of carotid embolism and a non-competent cerebral collateral circulation. Asymptomatic status was associated with the absence of any relevant mechanism.
authors: Irvine Laboratory for Cardiovascular Investigation and Research, Department of Vascular Surgery, Imperial College of Science, Technology and Medicine, Praed St, London, Paddington, W2 1NY, UK.
authors: T J
authors: TJ
authors: Tegos
authors: M M
authors: MM
authors: Sabetai
authors: P
authors: P
authors: Robless
authors: E
authors: E
authors: Kalodiki
authors: P
authors: P
authors: Bassett
authors: G
authors: G
authors: Stansby
authors: A N
authors: AN
authors: Nicolaides
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001161:Arteriosclerosis / Q000503:physiopathology*; D002340:Carotid Artery Diseases / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003097:Collateral Circulation; D003430:Cross-Sectional Studies; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018608:Ultrasonography, Doppler