Background and purpose: In patients with carotid artery occlusion (CAO), collateral flow may reduce the risk of ischemic stroke. Collateral flow via the ophthalmic artery (OphthA) and flow via leptomeningeal vessels have been considered secondary collaterals, which are recruited only if the primary collateral circulation via the circle of Willis is insufficient. The aim of this study was to investigate whether patients with symptomatic CAO who have secondary in addition to primary collaterals have a worse flow state of the brain than those without secondary collaterals, as measured by vascular reactivity testing.
Methods: We studied 70 patients with symptomatic CAO who were independent for their daily activities. In all patients, collateral circulation through the circle of Willis was present. Vascular reactivity, measured by means of transcranial Doppler sonography with carbogen inhalation, was compared between patients with and without secondary collaterals.
Results: CO2 reactivity was lower in 64 patients with (mean +/- standard deviation 8 +/- 14%) than in 6 patients without secondary collaterals (33 +/- 18%) resulting in a mean difference of 24% (95% confidence interval 12-37%; p < 0.01).
Conclusions: Patients with symptomatic CAO with collateral circulation through the OphthA or through leptomeningeal vessels in addition to collaterals via the circle of Willis have a worse hemodynamic status of the brain than those with Willisian collaterals only. Therefore the presence of these collaterals may indicate insufficiency of collateral blood flow via the circle of Willis.
Copyright 2002 S. Karger AG, Basel