In surgery, extirpation.

A benign tumor of the 8th cranial pair of nerves. Its symptoms may include: loss of audition, balance troubles, headaches, and tinnitus (hearing tinkles).

A nerve composed of two parts, the vestibular part, and the cochlear part with a superficial at the junction of the pons and medulla.

A chronic ailment of middle-aged people characterized by elongation of bones of the extremities and some cranium bones, mainly frontal bones, and jaw. It is also accompanied by enlargement of the nose and lips, and thickening of the soft tissues of the face.

A neoplasm of the glandular epithelium, as in pituitary adenoma.

Morphologically, an AVM is composed of a cluster of vascular structures. These vessels vary in size, and they include one or several nutrient arteries, a nidus, and one or many draining veins. Microscopically, the nidus is composed of a network of poorly differentiated and immature vessels, toward which the nutrient arteries converge, and from which thickened veins drain. Because of the great pressure gradient between both sides of the nidus and its relatively wide vascular channels, arteriovenous shunting occurs within the AVM's. The shunting involves complicated hemodynamics and caused the malformation to be subjected to pathological changes including rupture with hemorrhage, and thrombosis. The pressure gradient also alters the hemodynamics in the surrounding brain tissue and "steals" the blood supply from the adjacent structures. The "theft" might give the surrounding tissue a longstanding "hypoxic" status. Other pathological changes such as atrophy, focal or hemispheric, progressive reparative fibrosis, gliosis and, sometimes, calcification may occur.

Clinically, AVM's are the most common and described vascular malformations of the central nervous system (CNS). They occur in all parts of the CNS. Hemorrhage is the initial symptom in 50 to 80% and epileptic seizures in 10 to 47% of AVM patients. AVM's may cause other signs and symptoms, such as: increased intracranial pressure, progressive neurological dysfunctions, headaches, mental deterioration, and, in the case of children, cardiac insufficiency.

The initial symptoms are usually noted during the second or third decades of life. The true natural history of AVM's is not well understood. However, the annual risk of suffering a bleeding, once the AVM has been diagnosed, has been estimated at 2 to 4%, and mortality at 1 to 1,5%. For every hemorrhage, the estimated morbidity is 20 to 40% and mortality 10 to 25%. Besides, in the case of patients who have already suffered a hemorrhage, the risk of further bleedings is much greater than for those in whom the initial symptom is epilepsy.

An angiographically hidden AVM, which is inaccessible by surgical means, and highly risky.

An exam that allows viewing the blood vessels in the head. This is an invasive procedure requiring the introduction of a catheter, which is directly taken to the neck blood vessels, and the base of cranium. A contrast medium is injected to be able to view, thanks to the rapid succession of x-rays, the blood flow through the head cases, since the moment when they are filled with the contrast medium until the substance dilutes.

In radiotherapy, the usage of radioactive material such as radium, iridium, or gold, at the site or close to the site being treated.

An irregular cranial cavity contained in the dura mater, located at either side of the body of the sphenoid bone, extending from the medial end of the upper orbital fissure in front to the apex of the petrous temporal bone behind. It receives the superior ophthalmic vein, the superficial middle cerebral vein, and the sphenoparietal sinus, and communicates with the opposite cavernous sinus and with the transverse sinus and internal jugular vein by way of the petrosal sinuses. Commonly comprising one or more main venous channels, it contains the internal carotid artery and abducent nerve.

Swelling of the brain tissues due to an accumulation of liquid, caused by tumors, toxic substances, or interaction. Increase in brain volume due to an accumulation in its aqueous content. It may be due to: increased capillary permeability, swelling of brain cells in states of hypoxia or aqueous intoxication, and interstitial edema caused by hydrocephaly.

An X-shaped crossing of two elements or structures.

A device that causes beams of light or radiation to move in parallel rays. In radiology, a device which eliminates the peripheral portion of an x-ray beam using metallic tubes, cones, or diaphragms. A system of diaphragms made of an absorbing material designed to define the dimensions of a beam of radiation.

12 pairs of nerves originated in the brain.

An incision through the skull.

Measurement of radiation doses.

Complete removal of an organ or tissue.

7th cranial nerve; a mixed nerve consisting of efferent fibers supplying the facial muscles, the platysma muscle, the submandibular and lingual glands, and afferent fibers coming from the gustative glands, the two anterior thirds of the tongue, and its muscles. They are distributed through ear, face, palate and tongue.

In radiotherapy, the process of spreading the total required treatment dose over an extended period of time.

A unit to measure the absorbed radiation. 1 gy = 100 rads (rad = radiation absorbed dose).

A container for the radiation or imaging sources.

A neoplasm or tumor composed of neuroglial cells.

Something of uniform structure, composition, or nature.

Lack of uniform quality or consistence.

A preffix meaning "equal or similar".

In radiation, receiving the same radiation dose in different areas.

One of two or more atoms with the same atomic number but with different numbers of neutrons. Many isotopes are radioactive, and their nuclear composition is unstable.

Having similar qualities in every direction; having the same refraction.

Movement of cells (especially cancerous ones) from one part of the body to another; change in location of a disease or its manifestations from one organ to another which is not directly connected to the original. In general, it makes reference to the manifestations of a malignancy, with a secondary growth in a different location, which has arrived by means of the lymphatic or circulatory systems.

Number of cases appeared of a disease related to a specific population.

Percentage of deaths in a determined population.

A hard, slow-growing, usually vascular tumor occurring mainly along the meningeal vessels and superior longitudinal sinus invading the dura mater and the skull and leading to erosion and thinning of the skull.

A severe and sharp pain moving through a nerve.

The tissue forming the interstitial or supporting elements -cells and fibers- of the nervous system. It includes: astrocytes, oligodendroglia, microglia, ependyma, neurilemma, sheath cells or nerve fibers (cells of Schwann), and satellite cells of the cranial or spinal ganglia. Neuroglia acts as a connecting or supporting tissue, and it plays an important role in the reaction of the nervous system to infections or injuries.

Tumor of the glial neurological tissues.

Disease of the nerves.

A cluster; a nest-like structure; focus of infection; a nucleus or origin of a nerve.

Not lying in the same plane.

Near or around the sella turcica.

Partial or incomplete paralysis.

Sensation of numbness, prickling or tingling; heightened sensitivity experienced in central and peripheral nerve lesions.

A gland-like structure in the brain, shaped like a pine cone, and located in a pocket near the splenium of the corpus callosum. It appears to be the major site of melatonin biosynthesis in man. Effects of melatonin and exact function of the pineal body is unknown. Inhibition of secretion from the pineal gland is believed to be associated with the beginning of puberty.

A small gray rounded endocrine gland attached to the base of the brain by the infundibular stalk, a downward extension of the floor of the third ventricle. It averages 1.3 x 1.0 x 0.5 cm in size; synonym: hypophysis cerebri. Referred to as the master gland of the body. Secretes a number of hormones that regulate many of the bodily processes including growth, reproduction and various metabolic activities.

Coronal: Also known as the frontal plane; situated in the direction of the coronal suture; longitudinal plane passing through the body at right angle to the median plane.

Sagittal: Situated in the direction of the sagittal suture; an anterior/posterior plane parallel to the media plane of the body.

Transverse: Situated at a right angle to the long axis of a structure.

The use of high energy photons and alpha particles in the form of beams in treating certain diseases such as cancer or in selectively destroying overactive endocrine glands.

A method of precisely locating areas in space utilizing three-dimensional mapping, especially in the areas of the brain.

A concavity on the superior surface of the body of the sphenoid bone that houses the hypophysis cerebri (pituitary gland).

Above or over the sella turcica.

Cells of ectodermal origin that comprise the neurilemma.

Membranous covering of myelin sheath of a nerve.

A benign tumor of the neurilemma or sheath of Schwann of a nerve.

Fifth cranial nerve; a large mixed nerve arising from the side of the pons near its superior border. It is connected to the brain stem by two roots: a large sensory root and a small motor root. The sensory root has three large branches arising from it: the ophthalmic branch, the maxillary branch and the mandibular branch.