Calcium antagonists for aneurysmal subarachnoid haemorrhage

A subarachnoid haemorrhage is a bleed in the so-called subarachnoid space, which is the very small space between the brain and the skull, and which contains blood vessels that supply the brain. The cause of the bleeding usually is a rupture of a bulge in one of these vessels. This bulging or blister on a vessel is called an aneurysm. A subarachnoid haemorrhage is a relatively uncommon type of stroke; it accounts for about one in 20 (5%) of all strokes. Subarachnoid haemorrhage often occurs at a relatively young age: half the patients are younger than 55 years old. The outcome of patients after subarachnoid haemorrhage is generally poor: half the patients die within one month after the haemorrhage, and of those who survive the initial month, half remain dependent on someone else for help with activities of daily living (e.g. walking, dressing, bathing). One of the causes of poor outcome is a complication of subarachnoid haemorrhage called secondary ischaemia (ischaemia means lack of blood). This complication occurs four to 10 days (hence secondary) after the haemorrhage. The cause is not exactly known, but one of the factors involved is narrowing of blood vessels in the brain. Calcium antagonists are a type of drug that block calcium channels in cells and are often used for the treatment of high blood pressure. They have also been shown to counteract the narrowing of blood vessels after subarachnoid haemorrhage and to protect the brain against periods of ischaemia. This review of 16 trials, involving 3361 patients, has found that the outcome after subarachnoid haemorrhage, in terms of survival and being independent in activities of daily living, is improved by treatment with calcium channel blockers (antagonists). If the largest trial is excluded from the analysis, the results are no longer statistically significant, and therefore the evidence is not beyond all doubt. However, given the high likelihood of benefits and the modest risks associated with this treatment, the review authors conclude that calcium antagonists, in the form of oral nimodipine 60 mg every four hours, are useful in patients with subarachnoid haemorrhage from a ruptured aneurysm. Magnesium is another calcium antagonist with promising results, but larger trials with this drug are needed before we can be certain about a beneficial effect.