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Correlation of xenon-enhanced computed tomography-defined cerebral blood flow reactivity and collateral flow patterns
H A Smith1, J Thompson-Dobkin, H Yonas
1Department of Neurological Surgery, University of Pittsburgh, PA, School of Medicine.
Background And Purpose:
A chronic compromise of cerebral hemodynamics has been shown to identify a group of patients at an increased risk for stroke. Because a "steal phenomenon" induced by a vasodilatory challenge has characterized the group at greatest risk, it was hypothesized that these individuals would also have a severe compromise of primary collaterals and an increased dependence on leptomeningeal collaterals.
Methods:
Twenty-three patients with symptomatic cerebrovascular disease underwent angiography and xenon-enhanced computed tomographic cerebral blood flow studies before and after 1 g IV acetazolamide within 6 months of each other. Cerebral blood flow vasoreactivity was classified by whether cerebral blood flow increased (> 5%) or was unchanged (+/- 5%) (group 1) or fell by > 5% (group 2) in any vascular territory. Angiographic collateralization was classified into four types: normal (type 1), willisian (type 2), ophthalmic (type 3), and leptomeningeal (type 4).
Results:
Twenty percent (2/10) of group 1 patients and 69% (9/13) of group 2 patients (P = .0009) had leptomeningeal collaterals.
Conclusions:
A negative flow reactivity is significantly associated with a dependence on leptomeningeal collaterals and implies a state of maximal hemodynamic compromise.