It's A Brain (Aneurysm) Matter
A Brain Aneurysm, also referred to as a cerebral aneurysm or intracranial aneurysm, is thought to be a “weaknesses” or dilation (stretching) in one of the walls of a blood vessel, which bulge or balloon outward over time as a result of the continuous flow of blood and pressure against the thinning wall. One of the most common types of aneurysm, called a saccular or "berry" aneurysm, is known for looking like a berry hanging from a stem. Other, aneurysms, diffusely and circumferentially involve a whole segment of an artery, known as a fusiform aneurysm.
The actual mechanism of aneurysm formation depends on the aneurysm type but may involve a genetic propensity for development. This is not the kind of uncertainty one likes whether you are a patient, survivor or the leader in the worldwide fight against the disease. We, therefore, are working hard to change that on your behalf. Many patients with brain aneurysms have no underlying disorder that we know of. On the other hand, many known disorders are associated with increased risk of forming Brain Aneurysms such as polycystic kidney disease, sickle cell disease, and various connective tissue disorders for examples. More common conditions which promote aneurysm growth and increase the likelihood of rupture include hypertension and smoking.
Family, Forms & More
If you have a family history of brain aneurysms (Familial Aneurysms), you are encouraged to get screening that can detect an unruptured aneurysm. Screening may also be a good idea for those with new neurological symptoms, such as headaches or visual disturbances. Many individuals lead a normal life with an aneurysm not knowing that they ever had one. For those that do have a blood relative with an aneurysm or history of subarachnoid hemorrhage (“SAH” or brain bleeding), we usually recommend screening of first degree adult relatives with Magnetic Resonance Angiography (MRA) is usually advised. Normal MRA exams may need to be repeated at some intervals to make sure that new aneurysms do not develop.
Most “saccular” aneurysms, the most common type, look like a berry on a stem, bulge out on one side of the blood vessel (pictured above) and are discovered in middle-aged and older adults. This kind is very rare in young adults and extremely rare in children. Fusiform aneurysms, on the other hand, balloon out on all sides of a blood vessel and are more oblong in shape. When a saccular or fusiform aneurysm is found “incidentally”, during evaluation of some other problem (by MRI, most typically), the question of “how long has it been there” can usually only be estimated, unless previous imaging is available. There are many other rare types of aneurysms (such as the “mycotic” kind) which form for different reasons and at different times.
Two Or More
About 20-30% of patients have more than one aneurysm, and 5% will have three or more. In most cases, we don’t know the underlying reason; in a minority of patients a known predisposing disorder exists.