Cerebral hemorrhage

Intracranial hemorrhage includes parenchymal intracerebral haemorrhage (ICH) and subarachnoid haemorrhage (SAH). Increasing age and male sex are risk factors for ICH. Hypertension is the best documented modifiable risk factor for ICH. There may be a relation between ICH and low cholesterol levels, whereas there are conflicting data as to whether smoking and heavy alcohol consumption are risk factors. Increasing age and female sex are risk factors for SAH. There are data suggesting a higher incidence of SAH in Finland, Japan, and the New Zealand Maori population. Smoking is the best documented modifiable risk factor for SAH. There are conflicting data as to whether hypertension and alcohol consumption are risk factors for SAH. Oral contraceptive pills with higher doses of estrogen appear to be a risk factor for SAH. Available data on risk factors for ICH and SAH should be interpreted cautiously because the studies have methodologic problems so that the underlying demographic characteristics of the populations studied have varied significantly. Better designed risk-factor studies of both ICH and SAH are needed to assess similar populations using multivariate statistical analysis to determine which variables are independently significant, allowing for the confounding effects of other risk factors.