Occurs when part of an artery weakens, causing a blood-filled bulge or “ballooning” out of the arterial wall. If an aneurysm ruptures, it can lead to internal bleeding and even death.  Aneurysms can occur in several places within the body:  heart (aorta), abdomen, chest, brain, legs, groin, intestines, lungs, kidney, and neck.  If an aneurysm ruptures within the brain, it releases blood within the skull and can cause a stroke or death.  It can also cause raised intracranial pressure. Aneurysms can be idiopathic (of unknown cause) or they can be linked to a wide variety of causes, the most common to Chiarians is Heritable Disorders of Connective Tissue, such as Ehlers-Danlos Syndromes.