The significance of the cerebral collateral capacity in patients with carotid atheroma

Objectives: to identify the echodensity, stenosis of carotin plaques and ce rebral collateral capacity that were associated with various ipsilateral pr esentations (retinal, cerebrovascular, asymptomatic). Design: cross-sectional study. Materials:forty-four patients, with 44 plaques associated with various pres entations, 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), h yperechoic thigh GSM)]. The percentage (%) reduction of the mean velocity i n the middle cerebral artery (PRMCA) on transcranial Doppler, during clampi ng in carotid endarterectomy, was evaluated to distinguish the competent ce rebral collateral supply (low PRMCA) front the non-competent one (high PRMC A). Results: the retinal symptoms were associated with plaques of low median GS M (0), severe median stenosis (90%) and low median PRMCA (0.31) as contrast ed with the cerebrovascular symptoms (17 84%, 0.47, respectively) and asymp tomatic status (32, 83%, 0.4, respectively) [(p = 0.038 (GSM), p = 0.67 (st enosis), p = 0.15 (PRMCA)]. The retinal and the cerebrovascular symptoms we re 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 combi nation of carotid embolism and a non-competent cerebral collateral circulat ion. Asymptomatic status was associated with the absence of any relevant me chanism.