Circulatory and vascular changes after aneurysmal subarachnoid hemorrhage.

Delayed cerebral ischemia (DCI) is a major complication that afflicts approximately 30% of patients who suffer an aneursymal subarachnoid hemorrhage (SAH). DCI is often associated with neurological infarction, poor outcome and mortality. Though the pathogenesis of DCI is not yet clear, it is traditionally been attributed to angiographic vasospasm. Unfortunately, clinical trials based on this premise have mostly been disappointing, predominantly unable to prevent ischemic damage and improve patient outcome despite reducing angiographic vasospasm. More recently, increasing concern that vasospasm could not fully account for DCI development has incited novel proposals as to the pathogenesis of DCI. A general theme exists among these theories (microcirculatory constriction, cortical spreading depression, blood brain barrier breakdown, microthrombosis) in that a majority seems to revolve around dysfunction and changes to the microvasculature. This purpose of this review was then to juxtapose macrovascular and microvascular changes after SAH, and provide an overview of current and prospective treatments.