Hemorrhage: Almost 90% of patients who experience a cerebral hemorrhage have a past history of high blood pressure (hypertension). There is a greater risk of hemorrhage in certain areas of the brain: the basal ganglia, thalamus, cerebellum and the pons. The most common pathological mechanism for hemorrhage is the presence of an aneurysm, or weakening of the arterial wall. This aneurysm ruptures and hemorrhage results. Hemorrhages produce damage by mass effect, infarction, and direct destruction of nervous tissue by blood.