brain, spinal cord, and nerve disorders
Subarachnoid Hemorrhage (SAH)
Causes of SAH
Subarachnoid hemorrhage usually results from Overview of Head Injuries . However, subarachnoid hemorrhage due to a head injury causes different symptoms, is diagnosed and treated differently, and is not considered a stroke. Subarachnoid hemorrhage is considered a stroke only when it occurs spontaneously—that is, when the hemorrhage does not result from external forces, such as an accident or a fall. A spontaneous hemorrhage usually results from the following: The sudden rupture of an aneurysm in an artery in the brain Brain Aneurysms are bulges in a weakened area of an artery’s wall. Aneurysms typically occur where an artery branches. Aneurysms may be present at birth (congenital), or they may develop later, after years of high blood pressure weaken the walls of arteries. Most spontaneous subarachnoid hemorrhages result from congenital aneurysms. Aneurysms in an artery of the brain can run in families. About 6 to 20% of brain aneurysms may result from an inherited defect in an artery's wall. Hemorrhage due to a ruptured aneurysm can occur at any age but is most common among people aged 40 to 65. Less commonly, subarachnoid hemorrhage results from rupture of an abnormal connection between arteries and veins ( Brain Arteriovenous Malformations (AVMs) ) in or around the brain. An arteriovenous malformation may be present at birth, but it is usually identified only if symptoms develop. Subarachnoid hemorrhage can also result from bleeding disorders. 