If a blood vessel in the brain leaks or bursts and causes bleeding, a hemorrhagic stroke occurs. Compression from excessive bleeding may be so severe that oxygen rich blood is unable to flow to the brain tissue. A lack of oxygen in the brain can lead to swelling, or cerebral edema.A hemorrhage can rapidly cause brain damage and can be life-threatening. Since the brain cannot store oxygen, it relies upon a series of blood vessels to supply oxygen and nutrients. When a hemorrhage occurs, oxygen may no longer be able to reach brain tissue supplied by leaky or broken blood vessels.Complications can occur before or after medical treatment, and can include: Rebleed – until the damaged vessel is repaired, there is a risk of re-bleeding. This commonly occurs 24-48 hours after the first bleed and, if left untreated, carries an increased risk of further complications including death.