• Extended Glasgow Outcome Scale [ Time Frame: At six months ] [ Designated as safety issue: No ]
  

• Incidence of clinical vasospasm [ Time Frame: Within first 14 days ] [ Designated as safety issue: No ]
  
• Barthel Index [ Time Frame: At six months ] [ Designated as safety issue: No ]
  
• Modified Rankin Score [ Time Frame: At six months ] [ Designated as safety issue: No ]
  
• Modified National Institute of Health Stroke Score [ Time Frame: At six months ] [ Designated as safety issue: No ]
  
• Other major complications requiring intensive care unit admission [ Time Frame: During first 14 days ] [ Designated as safety issue: Yes ]
  

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.