PRIMARY OBJECTIVE: Experimental and clinical studies have suggested that 
magnesium has neuroprotective and vasodilatation properties. A meta-analysis was 
conducted to assess the effectiveness and safety of intravenous magnesium 
therapy in patients with aneurysmal subarachnoid haemorrhage (SAH).
RESEARCH DESIGN: Meta-analysis.
METHODS AND PROCEDURES: Medline, EMBASE and the Cochrane Library were searched 
for prospective controlled trials evaluating intravenous magnesium for treating 
SAH after a ruptured aneurysm without language restrictions. Two researchers 
performed the literature search and data extraction independently.
MAIN OUTCOMES AND RESULTS: Six prospective controlled trials involving 699 
patients were included in this meta-analysis. Magnesium infusion reduced the 
risk of poor outcome and delayed cerebral ischemia (DCI): the relative risk was 
0.62 (95% confidence interval (CI) 0.46-0.83) and 0.73 (95% CI 0.53-1.00), 
respectively. Sensitivity analyses were consistent with the meta-analysis. The 
withdrawal rate for adverse effects was higher in the magnesium-treatment arm 
compared to the placebo arm, RR 9.98 (95% CI 3.04-32.74).
CONCLUSION: The meta-analysis suggests that intravenous magnesium therapy 
reduces the risk of DCI and poor outcome after aneurysmal SAH. Serum magnesium 
should be routinely monitored for both effectiveness and safety considerations.