OBJECT: Despite the application of current standard therapies, vasospasm 
continues to result in death or major disability in patients treated for 
ruptured aneurysms. The authors investigated the effectiveness of continous 
MgSO4 infusion for vasospasm prophylaxis.
METHODS: Seventy-six adults (mean age 54.6 years; 71% women; 92% Caucasian) were 
included in this comparative matched-cohort study of patients with aneurysmal 
subarachnoid hemorrhage on the basis of computed tomography (CT) findings. 
Thirty-eight patients who received continuous MgSO4 infusion were matched for 
age, race, sex, treatment option, Fisher grade, and Hunt and Hess grade to 38 
historical control individuals who did not receive MgSO4infusion. Twelve grams 
of MgSO4 in 500 ml normal saline was given intravenously daily for 12 days if 
the patient presented within 48 hours of aneurysm rupture. Vasospasm was 
diagnosed on the basis of digital substraction angiography, CT angiography, and 
transcranial Doppler ultrasonography, and evidence of neurological 
deterioration. Symptomatic vasospasm was present at a significantly lower 
frequency in patients who received MgSO4 infusion (18%) compared with patients 
who did not receive MgSO4 (42%) (p = 0.025). There was no significant difference 
in mortality rate at discharge (p = 0.328). A trend toward improved outcome as 
measured by the modifed Rankin Scale (p = 0.084), but not the Glasgow Outcome 
Scale (p = 1.0), was seen in the MgSO4 treated group.
CONCLUSIONS: Analysis of the results suggests that MgSO4 infusion may have a 
role in cerebral vasospasm prophylaxis if therapy is initiated within 48 hours 
of aneurysm rupture.