Magnesium in subarachnoid haemorrhage: proven beneficial?

Subarachnoid haemorrhage (SAH) caused by a ruptured aneurysm accounts for only 5% of strokes, but occurs at a fairly young age and carries a worse prognosis. Delayed cerebral ischaemia (DCI) is an important cause of death and dependence after aneurysmal subarachnoid haemorrhage. The current mainstay of preventing DCI is nimodipine and maintenance of normovolemia, but even with this strategy DCI occurs in a considerable proportion of patients. Magnesium is an inexpensive, easily available neuroprotective agent and has been shown to reduce cerebral vasospasm and infarct volume after experimental SAH. In a subgroup analysis in the Cochrane review of all randomized clinical trials of calcium antagonists in SAH, magnesium reduced the occurrence of DCI and that of poor outcome. Magnesium is a promising agent to prevent the occurrence of secondary ischemia and to improve outcome in patients with SAH. Currently two large phase Il trials are being conducted that will hopefully provide definite evidence whether magnesium treatment is beneficial in SAH patients.