Impairment of cerebral perfusion and infarct patterns attributable to vasospasm after aneurysmal subarachnoid hemorrhage: a prospective MRI and DSA study.

BACKGROUND AND
PURPOSE: The objective of this study was to investigate disturbance of perfusion and infarct patterns attributable to cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH).
METHODS: One hundred seventeen patients with aneurysmal SAH specifically selected at high risk for CVS were enrolled in this prospective study. One hundred twelve patients underwent surgical (n=63) or endovascular (n=59) therapy. For assessment of CVS, relative diameter changes of proximal and distal vessel segments on follow-up angiography at day 7+/-3 after SAH were analyzed in relation to baseline measurements, and cerebral circulation times were measured. Postprocedure MRI was undertaken selectively at four time points: within 3 days, between days 4 and 6, day 7 to 14, and day 15 to 28 from onset of SAH, including perfusion- and diffusion-weighted images. Procedure-related lesions were excluded and CVS-associated infarct patterns analyzed.
RESULTS: Occurrence of angiographic CVS was as high as 87.5% between days 7 and 14 and 52.5% showed new infarcts. Eighty-one percent of the infarcts were related to severe CVS (vascular narrowing >66%) and significant (P<0.001) cerebral circulation times prolongation of 8.47+/-2.25 seconds (time-to-peak delay on perfusion-weighted image: 6.52+/-4.75 seconds), 16% were associated with moderate CVS (34% to 66% vascular narrowing; cerebral circulation times prolongation: 4.72+/-0.66 seconds). Besides territorial (47%), lacunar (20%), and watershed infarcts (26%), in 7%, band-like cortical lesions developed without evidence for severe CVS.
CONCLUSIONS: CVS after SAH may involve the complete arterial system from the circle of Willis up to the distal vessel segments. Depending on the variable types of collateral flow, location of affected vessels segments as well as the degree of CVS may induce different infarct patterns.