Angiographic vasospasm and delayed cerebral ischemia after subarachnoid hemorrhage: Moving from theoretical to practical research pertinent to neurosurgical care

Abstract

Background and purpose: Delayed cerebral ischemia (DCI) and angiographic vasospasm following subarachnoid hemorrhage (SAH) have been associated for more than 50years. We aimed to examine whether the knowledge gained by theoretical research on vasospasm has actually translated into better patient outcomes in practice.

Methods: This is a narrative review of the concept of vasospasm as a cause of DCI after SAH. We discuss recent studies that have assessed the accuracy and reliability of the diagnostic tests (transcranial Doppler ultrasound [TCD], CT angiography, and catheter angiography), which are used to identify SAH patients at-risk of DCI.

Results: Both the diagnostic accuracy of TCD and the reliability of CT angiography to identify patients in severe vasospasm are poor. For the gold standard catheter angiography, the repeatability of the diagnosis of vasospasm, made by multiple raters, is only fair. Interventions on angiographic vasospasm have never been proven to improve patient outcomes. A pragmatic trial integrating the meaning of the diagnosis of vasospasm into a study protocol that assesses the value of endovascular interventions in the prevention of DCI after SAH seems to be in order. Such a trial could provide a pragmatic definition of clinically meaningful vasospasm.

Conclusion: We must move beyond research conceived as an enterprise aiming to acquire theoretical knowledge to one where research is integrated into clinical practice to improve clinical outcomes in real time.

Keywords: Cerebral vasospasm; Delayed cerebral ischemia; Diagnostic studies; Pragmatic research; Reliability; Transcranial Doppler.