Glossary of Terms
Having to understand the medical terms associated with your condition can be overwhelming and frustrating. Whether you are planning your first consultation after diagnosis, or if you've just begun discussing treatment options with your physician, the glossary of terms can serve as a helpful reference tool.
Aneurysm - a thin-walled blister on an artery at the base of the brain.
Angiogram - the diagnostic radiology study performed to search for an aneurysm or vascular malformation. The radiologist passes a catheter up from an artery in the groin to the arteries in the neck; it then injects dye into the carotid and vertebral arteries while multiple x-rays are taken of the arteries in the brain.
Arteriogram - synonymous with angiogram
Artery - a thick-walled blood vessel carrying blood flow from the heart to any organ of the body, including the brain.
Arteriovenous malformation (AVM) - a particular type of vascular malformation of the brain. An abnormal collection or tangle of arteries and veins located within the substance of the brain. AVMs appear to be associated with a maldevelopment of the small capillaries which normally connect the arteries and veins.
Balloon angioplasty - in the setting of severe vasospasm (see below), the neuroradiologist may perform an angiogram and then pass a catheter with a balloon on its tip all the way up into the narrowed brain artery, then inflate the balloon to mechanically dilate the artery.
Bypass - in rare cases when an aneurysm can't be clipped or coiled, the surgeon may have to perform a bypass operation, bringing blood flow through a new channel beyond the aneurysm and then trapping the segment of the artery with the aneurysm between clips.
Capillary - small blood vessels that normally connect the arteries (which bring blood flow to the brain) to the veins (which carry the blood flow away from the brain). The capillaries are very thin-walled, allowing the blood cells to transfer oxygen and nutrients directly to the surrounding brain tissue.
Capillary telangiectasia - a particular type of vascular malformation of the brain. Typically located deep within the brain, this is a small abnormal collection of capillaries. They rarely, if ever, cause symptoms and are usually found by accident at the time of an autopsy, which has been performed for an unrelated reason.
Cavernous malformation - (also known as cavernous angioma or cavernoma). A particular type of vascular malformation of the brain. This is a compact collection of abnormal blood vessels that is located within the substance of the brain.
Clipping - the traditional surgical method for repairing an aneurysm. The surgeon exposes the aneurysm and then places a metal clip that opens and closes like a clothespin across the base of the aneurysm, so that no more blood can enter the aneurysm.
Coiling - a newer treatment for aneurysms. A neurosurgeon or neuroradiologist performs an angiogram and then passes a catheter all the way up into the skull to reach the aneurysm itself. The aneurysm is then filled with fine platinum wire to cause the aneurysm to clot off.
Craniotomy - the generic term for all operations in which the skull is opened including the surgical procedure for clipping an aneurysm or removing a vascular malformation.
CT - abbreviation for CT scan or computed tomography scan. This is a special form of x-ray that is often the first test performed when an aneurysm rupture is suspected. It is painless and is the best x-ray test to look for blood that has escaped after an aneurysm bleeds.
Embolization - a technique that may be used as part of the treatment of brain AVMs. This is performed by a neuroradiologist or a neurosurgeon. As an extension of an angiogram, a catheter is passed up into the arteries inside the brain, and the arteries supplying blood flow to the AVM are then blocked off from the inside with either glue, metal coils or a variety of other substances. This is often performed as a prelude to surgery, but occasionally may be curative without additional therapy.
Endovascular - a generic term for treatment of an aneurysm or vascular malformation from inside the blood vessel. Aneurysm coiling and AVM embolization are examples of endovascular procedures.
Gamma knife - a device that is used to deliver high-dose, focused beam radiation for the treatment of AVMs (and also tumors) of the brain. This is one of two commonly used ways to perform radiosurgery.
GDC - short for Guglielmi Detachable Coils, it is the type of coils most typically used to treat aneurysms today.
Hydrocephalus - a generic term that describes too much fluid building up inside the brain. This may occur after aneurysm rupture or bleeding from an AVM and may be life-threatening. Emergency treatment with placement of a drainage tube to relieve the pressure may be required (see below - ventriculostomy).
Intracerebral hemorrhage - bleeding into the substance of the brain itself results in a blood clot or "intracerebral hemorrhage." "Intra" means within, "cerebral" means brain, and "hemorrhage" means bleeding. This can result from bleeding within the brain from any cause, including vascular malformations (such as AVMs or cavernous malformations) and high blood pressure.
Intraventricular hemorrhage - bleeding into the fluid-filled cavities in the center of the brain known as ventricles. Blood within the ventricles can impair the brain's ability to absorb the fluid normally. If the fluid builds up, this is known as hydrocephalus (water on the brain).
Linac (linear accelerator) - a device that is used to deliver high-dose, focused beam radiation for the treatment of AVMs (and also tumors) of the brain. This is one of two commonly used ways to perform radiosurgery.
MRI - short for magnetic resonance imaging. This is a special radiology test that allows for excellent imaging of the brain. Paradoxically, MRI does not show up fresh blood as well as CT, so if bleeding from an aneurysm is suspected, CT is a better test.
MRA - short for magnetic resonance angiography. This test can detect most aneurysms and is often performed as a screening measure when an aneurysm is suspected.
Papaverine - a drug that causes blood vessels to dilate. In the setting of severe vasospasm, a neuroradiologist may perform an angiogram and then inject papaverine into the narrowed arteries to help them dilate.
Radiosurgery - the use of high-dose, focused beam radiation for the treatment of brain AVMs. This technique does not necessarily involve open surgery. Using computer guidance, it is a specialized technique for targeting the AVM for irradiation while sparing the surrounding brain.
Subarachnoid hemorrhage (SAH) - bleeding into the space around the brain (the subarachnoid space). This occurs when an aneurysm ruptures, but it may also result from other causes of bleeding around the brain including a head injury from trauma.
Vascular malformation - an abnormality in the development of the blood vessels within the brain resulting in an abnormal collection or pattern of blood vessels in the brain.
Vasospasm - Four to fourteen days after an aneurysm ruptures, the blood vessels at the base of the brain may develop spasm or narrowing. If severe, this can result in stroke.
Vein - a thick-walled blood vessel carrying blood flow away from an organ and back toward the heart.
Venous angioma - also known as developmental venous anomaly. This is one type of vascular malformation of the brain. It represents an unusual pattern of development of the veins in a particular part of the brain. Venous angiomas rarely cause symptoms.
Ventriculostomy - a drainage tube inserted through a small hole in the skull into the fluid-filled spaces in the center of the brain to drain an abnormal build-up of fluid (hydrocephalus).
Wrapping - in rare cases when an aneurysm can't be clipped or coiled, the surgeon may choose to wrap the aneurysm with gauze material to promote scarring around the aneurysm wall and decrease the risk of future bleeding.
