Mechanisms of alcohol-related strokes

Epidemiological investigations have shown a linear positive correlation between the risk of haemorrhagic stroke and level of alcohol consumption. Ischaemic stroke shows a weaker relationship, which is J-shaped, suggesting that regular light-to-moderate alcohol consumption may carry a decreased risk. Case reports and case-control studies indicate that heavy recent drinking, but not heavy former drinking, increases the risk for both types of stroke. Larger amounts of alcohol are needed to trigger aneurysmal subarachnoid haemorrhage than spontaneous intracerebral haemorrhage. The increased risk caused by recent heavy drinking may be partly due to elevated systolic blood pressure, but alcohol may also provoke cerebral arterial vasospasm, as observed in animal experiments. Alcohol-induced fluctuation in haemostatic and fibrinolytic factors has not been proved to precipitate alcohol-related strokes, but may contribute to both an increase and a decrease of the risk. Subtypes of ischaemic stroke associate differently with alcohol consumption. A recent series of patients with ischaemic brain infarction showed that of the victims having a high and medium risk for cardiogenic embolism, 50% and 45% were intoxicated, respectively. This suggests that cardiogenic embolism is a significant mechanism leading to ischaemic stroke during heavy drinking of alcohol.