BACKGROUND AND PURPOSE: Angiographic vasospasm frequently complicates subarachnoid hemorrhage and has been implicated in the development of delayed cerebral ischemia. Whether large-vessel narrowing adequately accounts for the critical reductions in regional cerebral blood flow underlying ischemia is unclear. We sought to clarify the relationship between angiographic vasospasm and regional hypoperfusion.
METHODS: Twenty-five patients with aneurysmal subarachnoid hemorrhage underwent cerebral catheter angiography and 15O-positron emission tomographic imaging within 1 day of each other (median of 7 days after subarachnoid hemorrhage). Severity of vasospasm was assessed in each intracranial artery, whereas cerebral blood flow and oxygen extraction fraction were measured in 28 brain regions distributed across these vascular territories. We analyzed the association between vasospasm and perfusion and compared frequency of hypoperfusion (cerebral blood flow
RESULTS: Twenty-four percent of 652 brain regions were supplied by vessels with significant vasospasm. Cerebral blood flow was lower in such regions (38.6±12 versus 48.7±16 mL/100 g/min), whereas oxygen extraction fraction was higher (0.48±0.19 versus 0.37±0.14, both P
CONCLUSIONS: Angiographic vasospasm is associated with reductions in cerebral perfusion. However, regional hypoperfusion and oligemia frequently occurred in territories and patients without vasospasm. Other factors in addition to large-vessel narrowing must contribute to critical reductions in perfusion.
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