Haemodynamic Evaluation of Cerebral Perfusion After Subarachnoid Haemorrhage — a Review

The pathophysiology of delayed cerebral ischaemia following aneurysmal subarachnoid haemorrhage is reviewed in the context of the techniques available to study the cerebral circulation in these circumstances. The intravenous 133Xenon technique has been used to assess cerebrovascular reactivity to a period of brief hypotension and is shown to be a powerful predictor of which patients will develop delayed ischaemia following surgery. The potential of transcranial Doppler to substitute for freely diffusible indicator techniques is discussed.