Delayed ischemia after subarachnoid hemorrhage: result of vasospasm alone or a broader vasculopathy?

The term vasospasm is commonly used to describe constriction of cerebral blood vessels after subarachnoid hemorrhage which results in the restriction of blood flow and ischemia in affected portions of the brain. The pathophysiological changes that underlie vascular constriction after subarachnoid hemorrhage include changes within the vessel walls themselves, alteration of the levels of several vasoactive substances, and broader pathological conditions such as immune responses, inflammation, and oxidative damage. In this review, we summarize the current state of knowledge concerning the processes that occur in cerebral blood vessels after subarachnoid hemorrhage and how they may be involved in the development of vasospasm. We also propose that, rather than merely vasospasm, the multitude of vascular effects occurring after subarachnoid hemorrhage can be best described as a post-subarachnoid hemorrhage vasculopathy.