The neuroprotective effects of Magnesium on Brain have been reported in experimental models of traumatic brain injury, cerebral ischaemia and acute subarachnoid haemorrhage.
Magnesium on Brain reduces infarct volume in various animal models of embolic stroke. The mechanisms by which magnesium protects include the reduction of presynaptic release of glutamate, blockade of NMDA receptors, smooth muscle relaxation, suppression of cortical spreading depression, and improvement of mitochondrial calcium buffering and blockage of calcium entry via voltage-gated channels.
The application of Magnesium on Brain in aneurysmal subarachnoid haemorrhage in 283 patients reduced the risk of delayed cerebral ischaemia by 34% and the risk for poor outcome after 3 months by 23%. Therefore, an international phase III trial is planned to validate these results.
But the human trials of Magnesium on Brain in stroke have yielded conflicting results; several small pilot trials reporting a favourable outcome and the large multi-centric trial documenting no reduction in the risk of poor outcome.
More recent clinical trials have identified several agents that may soon become part of the routine management of patients with SAH. The endothelin antagonist clazosentan was mentioned earlier in this section.
A randomized, blinded, placebo-controlled trial reported fewer new ischemic deficits and improved outcome among patients who received magnesium sulfate starting within 4 days of SAH. Two phase II trials have examined the post-SAH administration of statins. T
ogether, these trials showed reductions in vasospasm, delayed ischemic deficits, and improvement in outcome. Although some centers have already implemented some of these therapies as part of the local routine, widespread adoption is not likely until the completion of larger trials that confirm these initial results.
Lynch JR, Wang H, McGirt MJ, et al: Simvastatin reduces vasospasm after aneurysmal subarachnoid hemorrhage: results of a pilot randomized clinical trial. Stroke 2005; 36:2024-2026.
Roos Y, Rinkel G, Vermeulen M, et al: Antifibrinolytic therapy for aneurysmal subarachnoid hemorrhage. Stroke 2003; 34:2308-2309.