The IMASH trial is a simple, randomized, double-blinded, placebo-controlled, multi-center trial to answer the question: "Does intravenous magnesium sulfate improve clinical outcome after aneurysmal subarachnoid hemorrhage?"

Vasospasm worsen outcome in patients with aneurysmal subarachnoid hemorrhage (ASAH).

Magnesium is known to dilate cerebral arteries and to block N-methyl-D-aspartate receptors in the injured neurons.

Intravenous magnesium may prevent vasospasm after subarachnoid hemorrhage and may protect neurons against damage during established vasospasm.

The IMASH trial is a randomized, placebo-controlled, double-blinded, multi-center trial to evaluate the effect that intravenous magnesium sulfate infusion on the clinical outcome of patients with aneurysmal subarachnoid haemorrhage.

Methods:

After obtaining randomisation code:

• Start MgSO4 20 mmol over 30 minutes, followed by infusion of 80 mmol/day or equivalent volume of saline within 48 h after onset of symptom,
• Study drug to be infused for 14 days from the day of hemorrhage (regarded as day 0).
• Measure plasma magnesium concentration daily and perform transcranial Doppler to monitor blood flow velocities of both middle cerebral arteries and extracranial segment of the internal carotid arteries.
• Plasma magnesium concentration in the IV MgSO4 group should be raised to 2.0-2.5 mmol/L or twice the serum baseline level. Patients that are randomized to saline infusion will only have their magnesium levels normalized if there is a clinical indication to do so.

Outcome assessment Primary outcome: Extended Glasgow Outcome Scale at six months Secondary outcome: Incidence of clinical vasospasm, Barthel Index; modified Rankin score, modified National Institute of Health Stroke Score, MCA velocities, other major complications

Study duration:

6 years with a refined sample size of 340 after analysis of pilot study data; with planned interim analysis.

Inclusion Criteria:

• ASAH (as indicated by CT scan or lumbar puncture and an intracranial aneurysm confirmed by computer tomographic or conventional angiography)
• Within 48 hrs of ictus (hemorrhage event)

Exclusion Criteria:

• Pregnancy
• Major renal, hepatic or pulmonary disease
• Major cardiac disease or recent myocardial infarct (< 6 months)
• Age less than 18 years
• Moribund condition on admission (defined as a patient that is in such a poor clinical condition that further active neurosurgical management would not be anticipated)