Basic Medical Terms

Having a sudden onset.

Any abnormal or injured tissue. A cavernous angioma is a lesion.

Not contained. Hemorrhages which bleed outside of the cavernous angioma into the surrounding brain tissue are considered overt.

A group of cells which are united to perform the same function.

A new growth of tissue in which multiplication of cells is uncontrolled and progressive. When a tumor is benign, cell multiplication within the tumor is minimal. The benign tumor does not “spread”, or cause growth of new tumors in other areas. Cavernous angiomas have been considered benign tumors by some researchers.

Blood and Blood Vessel Terminology

A blood vessel through which blood passes away from the heart and into other parts of the body. Blood flows through arteries with a great deal of pressure resulting from the pumping action of the heart. A pulse can be heard and felt in an artery. When arteries are ruptured, they bleed profusely. Cavernous angiomas do not involve arteries. As arteries reach their destinations, they branch and become much smaller vessels called arterioles.

Tiny vessels that connect the arterioles and venules. Capillaries are semi-permeable and allow for exchange of blood between
vessels and the surrounding tissue. Some researchers believe that some cavernous angiomas begin as abnormal capillaries.

The movement of blood through the body. The illustration to the left shows the junction of the arterial and the venous systems. The largest light colored vessel is an artery, which moves oxygenated blood from the heart. Arteries branch into arterioles which then branch into capillaries. The darker vessels are the venous system, which moves blood from the capillaries into venules which join to form veins. The veins carry blood back to the lungs for oxygenation.
The layer of cells that lines the blood vessels and other organs. Cavernous angiomas are comprised of endothelial cells that lack the support of the outer layers of blood vessel. This makes them leaky and fragile.

The escape of blood from the vessels. Cavernous angiomas
exhibit three types of hemorrhage:

  1. Angiomas can bleed slowly within the walls of the angioma and remain quite small. A small hemorrhage may not require surgery, but may be reabsorbed by the body. However, continued small hemorrhages in the same cavernous angioma often cause deterioration in function.
  2. Angiomas can bleed more profusely within the walls of the angioma. This can cause them to grow and put pressure on the surrounding brain tissue.
  3. Finally, angiomas may bleed through a weak spot in the angioma wall into the surrounding brain tissue. This is called an overt hemorrhage.

An iron deposit which is a blood breakdown product. When a hemosiderin ring is seen around a cavernous angioma on MRI, this means that the cavernous angioma bled some time in the past.

The formation of a blood clot along the wall of a blood vessel. This reduces or cuts off blood flow into the area beyond the clot.

One of the vessels that carries blood from the capillaries back to the heart. Blood traveling through veins moves with much less pressure than blood traveling through arteries. Veins begin as venules, small veins, and combine to form veins as they get closer to the heart.

The part of the brain which connects the cerebral hemispheres with the spinal cord. The brainstem consists of a number of structures including the pons, medulla oblongata, and mid-brain (reticular formation, raphe nucleus, substantia nigra). Some people also include the structures of the diencephalon (thalamus, pineal gland, habenula, caudate and lenticular nucleii, and hypothalamus) as part of the brainstem. These structures are responsible for the most basic life functions.

The part of the brain that lies between the brainstem and the back of the skull. It is primarily concerned with coordination of movement.

The main portion of the brain that occupies the upper part of the skull. It is divided into two hemispheres which are connected by the corpus collosum. The cerebrum forms the largest part of the human central nervous system. Each half of the cerebrum contains four sections, or lobes. They are the frontal lobe, the parietal lobe, the temporal lobe, and the occipital lobe. Below the cerebrum are the structures of the cerebellum and brainstem.

Cerebral Cortex
The outer layer of the cerebrum. The cerebral cortex is the 3 mm layer of gray substance covering the surface of each cerebral hemisphere.

Dura Mater
The outermost, toughest and most fibrous of the three membranes covering the brain and spinal cord.

Epidural or Extradural
Outside of the dura mater. For cavernous angiomas, this term is most often used in reference to a very rare condition in which there are lesions between the spinal cord and vertebra.

Gray Matter
This term is most commonly used as another name for tissue of the cerebral cortex, which makes up the outer layer of the brain. This tissue is colored gray. Although other areas of the brain are also gray, such as the thalamus, they are usually not included when medical or lay people use this term.

Below the level of the tentorium of the cerebellum. The tentorium is a layer of dura mater that supports the occipital lobes and covers the cerebellum. The cerebellum, pons, medulla, midbrain, and fourth ventricle lie below this layer and are considered infratentorial. About 27% of cavernous angiomas are infratentorial. [1]

Most interior portions of the brain or spinal cord. This term is most often used when referring to cavernous angiomas of the spinal cord.

The three membranes that envelop the brain and spinal cord: the dura mater, pia mater, and arachnoid.

Below the level of the arachnoid layer. In other words, below the level of the meninges of the brain.

Above the level of the tentorium, a layer of dura mater which supports the occipital lobes and covers the cerebellum. The cerebral hemispheres, thalamus, basal ganglia, lateral and third ventricles, and hypothalamus lie above this level and are considered supratentorial. About 73% of cavernous angiomas are supratentorial. [2]

White Matter
Another name for the tissue located in the interior of the brain. This tissue is white in color. It is located under the cerebral cortex, which is colored gray.

Cavernous Angioma Life Cycle

The process by which tissue becomes hard by a deposit of calcium salts within the tissue.

De Novo Lesion
A cavernous angioma that was not present at birth. Developing de novo lesions is a hallmark of familial cavernous angioma. It may also occur as the result of radiation, physical trauma, or other insults to the brain.

A way to measure changes in a cavernous angioma over time. For example, the incidence of hemorrhage is thought to be 0.3% per lesion-year. This means that if a person has 1 cavernous angioma and they live 75 years, their risk of hemorrhage over the course of their life is 22.5%:

  • 75 years x 1 angioma x .003 = 0.225
  • If a person has 15 angiomas and lives to 75, they are likely to have at least 3 hemorrhages during their lifetime:
  • 75 years x 15 angiomas x .003 = 3.375

Disability-Related Terminology

Assistive Technology Computer software and hardware devices that allow individuals with physical limitations to use the computer and other household and work environment equipment. For example, speech assistive technology can allow an individual with hand or arm limitations to use voice to control his or her computer.

Rankin Scale
The Rankin disability scale measures the degree of disability an individual has. A number of research studies make use of this scale. There are 5 grades:

  • Grade 1 – none or almost none
  • Grade 2 – slight. A person may not be able to do all of things she could previously, but she is able to take care of herself.
  • Grade 3 – moderate. A person requires some adjustments in daily living, but can do the essentials without the help of another person. For example, he may need a cane to walk or may be unable to drive.
  • Grade 4 – moderate severe. A person requires another person’s help to take care of herself. She may need help dressing or bathing. She can not walk without someone’s assistance.
  • Grade 5 – severe. A person requires constant nursing care, because he is bedridden. He is likely to be incontinent.


Angiographically Occult
A description of vascular malformations that can not be seen on an angiogram. Cavernous angiomas are angiographically occult because blood flow through the lesion is low.

Computerized Axial Tomography (CAT or CT scan)
An x-ray technique that produces pictures of consecutive slices of a body part. Cavernous angiomas can be seen using a CAT scan, but are often difficult to distinguish from other types of tumors. The slices of the CT scan may not be close enough to detect all of the cavernous angiomas a person might have. CT is useful for gross visualization of a large cavernous angioma, e.g. to track growth.

A process in which gadolinium dye is injected into a person’s bloodstream during an MRI to increase the contrast between light and dark areas.

Gradient Echo Sequences
This is a type of magnetic resonance imaging that is very accurate in detecting cavernous angiomas. A more precise, technical definition can be found at the FONAR MRI glossary

Magnetic Resonance Angiography
A form of magnetic resonance imaging (see MRI below) used to study blood vessels and blood flow. MRA is used to differentiate cavernous angiomas from other types of vascular abnormalities.

Magnetic Resonance Imaging
A method of imaging soft tissues of the body, such as the brain and spinal cord, by applying an external magnetic field. Magnetic resonance images distinguish between hydrogen atoms in different environments and produces a picture of these environments.

Susceptibility Weighted Imaging
This is a type of magnetic resonance imaging that is very accurate in detecting cavernous angiomas. For those with the hereditary form of the illness. susceptibility weighted imaging (SWI) sequences will typically show twice as many lesions as gradient echo sequences. This does not mean that a patient has developed new lesions, but rather that the imaging technique is more sensitive.

Other Types of Vascular Malformations

Arterio-Venous Malformation (AVM)
A vascular abnormality in which arteries and veins have a direct connection (shunt) rather than having blood flow through a bed of capillaries. AVM’s are high flow malformations.

Capillary Telangiectasia
Capillary telangiectasias are extremely small lesions composed of dilated capillaries. They have no symptoms. Some researchers believe that these malformations can develop into cavernous angiomas.

Venous Angioma
Also known as venous malformation or developmental venous anomaly. Venous angiomas consist of one or more malformed veins, often in the deep white matter of the brain. Most commonly, small veins which originate in the most interior parts of the brain are arranged in a fan shape and drain toward the outer portions of the brain into one or more dilated draining veins. These draining veins then drain out toward the cortex. There is normal brain tissue between the veins, and no arteries are found associated with the venous angioma. Most often, venous angiomas have no symptoms. Very rarely, they exhibit calcification, hemorrhage or spontaneous thrombosis or they may cause headache. They are believed to be found in 1 in 50 people. Venous angiomas are often associated with cavernous angiomas, particularly in people who have a solitary cavernous angioma and may play a role in their development.


Gamma Knife
A radiosurgery procedure in which focused gamma radiation beams are directed at a tumor or vascular malformation.

Linear Accelerator
A radiosurgery device similar to gamma knife which can direct either focused protons or gamma radiation at a tumor or vascular malformation.

Shaped Beam
A radiosurgery procedure which allows treatment of irregularly shaped tumors or vascular malformations.

For a more complete discussion, visit Epilepsy Action

Also known as a “stop and stare” seizure. The person having the seizure stops what they are doing and blankly stares into space. The person is not aware that they have had a temporary interruption of their activity.

Complex Partial
A type of seizure in which there is a loss of awareness and the person engages in “automatisms” – behaviors such a chewing, swallowing, picking at clothes, or scratching.

Simple Partial
A type of seizure in which a person remains aware but is unable to stop their experience or behavior. The seizure behavior depends on the area of the brain affected. The seizure can result in such things as intense feelings, uncontrolled movements, vision problems, or speech problems.

Formerly known as “grand mal”. This is the classic seizure and involves the entire brain. During a tonic-clonic seizure, a person loses consciousness, falls to the ground, and may stop breathing for a short period. They then have a period of jerky limb movements after which they go limp, but remain unconscious. Gradually the person regains consciousness and will likely feel very tired.

Traditional Surgery

A surgical procedure in which a portion of skull is removed in order to access the brain.

A surgical procedure in which the skull is opened in order to access the brain.

Image Guided Surgical Navigation: Computer-Assisted Stereotaxy, Frameless Stereotaxy
These are techniques in which imaging, such as MRI, is used during surgery to precisely locate a cavernous angioma. It allows for more precision in removing the cavernous angioma, and may eventually reduce the invasiveness of cavernous angioma resection.

Surgical removal of a cavernous angioma or other mass.


[1] Hsu, FPK, Rigamonti, D and Huhn, SL. Epidemiology of cavernous malformations. In Cavernous Malformations, Awad IA and Barrow DL eds., Park Ridge, IL: AANS, 1993.

[2] Ibid.

General References Awad, IA and Barrow, DL. eds.,Cavernous Malformations, Park Ridge, IL: AANS, 1993.
Dorland’s Illustrated Medical Dictionary, 29th edition