Effects of magnesium sulfate infusion on cerebral perfusion in patients after aneurysmal SAH.

Background: A meta-analysis of current data suggests that magnesium sulfate infusion improves the outcome after aneurysmal subarachnoid hemorrhage through a reduction in delayed ischemic neurological deficit. Two multi-center randomized controlled trials are currently underway to investigate this hypothesis. The possible pharmacological basis of this hypothesis includes neuroprotection and vasodilatation. We aim to investigate the cerebral hemodynamic effects of magnesium sulfate infusion in aneurysmal subarachnoid hemorrhage patients.

Method: A total of 12 patients who had experienced aneurysmal subarachnoid hemorrhage were randomized to magnesium sulfate infusion (n = 6) or placebo infusion (n = 6) for 14 days. Each patient had two perfusion MRIs performed, one in the first week after subarachnoid hemorrhage and one in the second week after subarachnoid hemorrhage.

Findings: Age, sex, and Fisher CT grade were not different between the two groups. All but one patient were of WFNS Grade I to II on presentation. There was no increase in rCBV, rCBF and MTT between the two perfusion scans within the same group or between the two groups.

Conclusion: Magnesium sulfate infusion, in the dosage of current clinical trials, did not increase cerebral blood volume and cerebral blood flow, as postulated by dilation of small vessels and/or collateral pathways.