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Radiosurgery Center Glossary of Terms 

5-fluorouracil: An anticancer drug

A

Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer).

Adenocarcinoma: A cancer that develops in the lining or inner surface of an organ. More than 95 percent of prostate cancers are adenocarcinoma.

Adenoma: A benign tumor that arises in or resembles glandular tissue. If it becomes cancerous, it is called an adenocarcinoma.

Adjunct or adjuvant treatment: One treatment given in addition to another. The treatments work together to make each more effective. 

Adverse reaction: In pharmacology, any unexpected or dangerous reaction to a drug. An unwanted effect caused by the administration of a drug. The onset of the adverse reaction may be sudden or develop over time. 

Acoustic: Having to do with sound or hearing. The acoustic nerve (the 8th cranial nerve) is concerned with hearing and the sense of balance and head position. An acoustic neuroma is a tumor on the acoustic nerve.

Acoustic neuroma: A benign tumor that may develop on the hearing and balance nerves near the inner ear. The tumor results from an overproduction of Schwann cells -- small sheet-like cells that normally wrap around nerve fibers like onion skin and help support the nerves. When growth is abnormally excessive, Schwann cells bunch together, pressing against the hearing and balance nerves, often causing gradual hearing loss, tinnitus (ringing in the ears), and dizziness. If the tumor becomes large, it can interfere with the facial nerve, causing partial paralysis, and eventually press against nearby brain structures, becoming life-threatening. 

Aflatoxin: A toxin produced by mold that can damage the liver and may lead to liver cancer. Aflatoxins cause cancer in some animals.

Anatomy: The study of form. Gross anatomy involves structures that can be seen with the naked eye. It is as opposed to microscopic anatomy (or histology) which involves structures seen under the microscope. Traditionally, both gross and microscopic anatomy have been studied in the first year of medical school in the U.S. The most celebrated textbook of anatomy in the English-speaking world is Gray's Anatomy, still a useful reference book. The word "anatomy" comes from the Greek ana- meaning up or through + tome meaning a cutting. Anatomy was once a "cutting up" because the structure of the body was originally learned through dissecting it, cutting it up. The abbreviation for anatomy is anat.

Androgen: A male sex hormone that promotes the development and maintenance of the male sex characteristics. The major androgen is testosterone. 

Androgenic: Pertaining to the development of male characteristics, including body hair, the genital organs and muscle mass. "Androgenic" is the adjective form of the noun "androgen," a word referring to any of the male hormones, including testosterone and androsterone. 

Anemia: The condition of having less than the normal number of red blood cells or less than the normal quantity of hemoglobin in the blood. The oxygen-carrying capacity of the blood is, therefore, decreased. 

Aneurysm: A localized widening (dilatation) of an artery, vein, or the heart. At the area of an aneurysm, there is typically a bulge and the wall is weakened and may rupture. The word "aneurysm" comes from the Greek "aneurysma" meaning "a widening." 

Angiogenesis: The process of developing new blood vessels. Angiogenesis is important in the normal development of the embryo and fetus. It also appears important to tumor formation. Certain proteins, including angiostatin and endostatin, secreted by tumors work (at least in mice) by interfering with the blood supply tumors need. Angiostatin is a piece of a larger and very common protein, plasminogen, that the body uses in blood clotting. Endostatin is a piece of a different protein, collagen 18, that is in all blood vessels.

Angiogram: An x-ray of blood vessels which can be seen because the patient receives an injection of dye to outline the vessels on the x-ray.

Angiography: A procedure performed to view blood vessels after injecting them with a radio opaque dye that outlines them on x-ray. This technique can be usefully used to look at arteries in many areas of the body, including the brain, neck (carotids), heart, aorta, chest, pulmonary circuit, kidneys, gastrointestinal tract, and limbs. 

Aphasia: One in a group of speech disorders in which there is a defect or loss of the power of expression by speech, writing, or signs, or a defect or loss of the power of comprehension of spoken or written language. See, for example, auditory aphasia. 

Apraxia: The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function. Apraxia is not related to a lack of understanding or to any kind of physical paralysis but is caused by a problem in the cortex of the brain. 

Artery: A vessel that carries blood high in oxygen content away from the heart to the farthest reaches of the body. Since blood in arteries is usually full of oxygen, the hemoglobin in the red blood cells is oxygenated. The resultant form of hemoglobin (oxyhemoglobin) is what makes arterial blood look bright red.

Ataxia: Wobbliness. Incoordination and unsteadiness due to the brain's failure to regulate the body's posture and regulate the strength and direction of limb movements. Ataxia is usually a consequence of disease in the brain, specifically in the cerebellum which lies beneath the back part of the cerebrum.

Ascites: Abnormal buildup of fluid in the abdomen. Ascites can occur as a result of a number of conditions, including severe liver disease and the presence of malignant cells within the abdomen. 

Astrocytoma: A tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes. The location of the tumor depends on the age of the person. In adults, astrocytomas most often arise in the cerebrum whereas in children, they may arise in the brain stem, cerebrum, and cerebellum. 

Avastin: The first drug in a new class designed to treat cancer by compromising its blood supply. Avastin (bevacizumab) is believed to prevent angiogenesis, the formation of new blood vessels that supply the tumor with blood, oxygen and other nutrients and allow the tumor to grow and metastasize to other sites in the body. Additionally, Avastin may interfere with tumor growth by causing blood vessels to shrink away from a tumor. 

Arteriovenous malformation (AVM) is a congenital disorder of blood vessels in the brain, brainstem, or spinal cord that is characterized by a complex, tangled web of abnormal arteries and veins connected by one or more fistulas (abnormal communications). Symptoms of arteriovenous malformations include seizures and headaches.

Astrocytoma: A brain tumor arising in the supportive tissue of the brain. They are the most common primary CNS tumors, representing about half of all primary brain and spinal cord tumors.

B

Basal Ganglia: Masses of nerve cells deep within the brain at the base of cerebral hemispheres.

Benign: Not cancer. Not malignant. A benign tumor does not invade surrounding tissue or spread to other parts of the body. A benign tumor may grow but it stays put (in the same place).

Bile: Bile is a yellow-green fluid that is made by the liver, stored in the gallbladder and passes through the common bile duct into the duodenum where it helps digest fat. The principal components of bile are cholesterol, bile salts, and the pigment bilirubin.

Benign prostatic hyperplasia: Abbreviated BPH. A noncancerous prostate problem in which the normal elements of the prostate gland grow in size and number. Their sheer bulk may compress the urethra, which courses through the center of the prostate, impeding the flow of urine from the bladder through the urethra to the outside. This leads to urine retention and the need for frequent urination. If BPH is severe, complete blockage can occur.

Bevacizumab: Generic name for a monoclonal antibody anticancer drug. See: Avastin.

Biopsy: The removal of a sample of tissue for purposes of diagnosis. (Many definitions of "biopsy" stipulate that the sample of tissue is removed for examination under a microscope. This may or may not be the case. The diagnosis may be achieved by other means such as by analysis of chromosomes or genes.) 

Blastoma: A tumor whose cells have embryonic characteristics, fast-growing and invasive.

Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".

BPH: Benign prostatic hyperplasia which is also known as benign prostatic hypertrophy. Nonmalignant enlargement of the prostate gland

Brain: That part of the central nervous system that is located within the cranium (skull). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."

Brain cancer: Cancer of the central information processing center of the body. Tumors in the brain can be malignant or benign, and can occur at any age. Only malignant tumors are cancerous. Primary brain tumors cancer initially forms in the brain tissue. Secondary brain tumors cancers are cancers that have spread to the brain tissue (metastasized) from elsewhere in the body. Secondary brain cancer is named for the organ or tissue in which the cancer begins, such as lung cancer with secondary brain metastasis.

Brain stem: The stem like part of the brain that is connected to the spinal cord. Or conversely, the extension of the spinal cord up into the brain. The brain stem is small but important. It manages messages going between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate, and blood pressure. The brain stem also controls consciousness and determines whether one is awake or sleepy. 

Brain swelling: See: Cerebral edema.

Brain tumor: A benign or malignant growth in the brain. Primary brain tumors arise in brain tissue. Secondary brain tumors are cancers that have spread to the brain tissue (metastasized) from elsewhere in the body. Brain tumors can and do occur at any age.

Brainstem: The lowest part of the brain which merges with the spinal cord and provides the major route by which the upper realms of the brain send information to, and receives information from, the spinal cord and peripheral nerves. The brainstem consists of the medulla oblongata, midbrain, and pons. All but two of the 12 cranial nerves originate in the brainstem. The brainstem influences basic processes such as alertness, breathing, blood pressure, and heart rate.

Breast cancer: Breast cancer is diagnosed with self- and physician-examination of the breasts, mammography, ultrasound testing, and biopsy. There are many types of breast cancer that differ in their capability of spreading to other body tissues (metastasis). Treatment of breast cancer depends on the type and location of the breast cancer, as well as the age and health of the patient. The American Cancer Society recommends that a woman should have a baseline mammogram between the ages of 35 and 40 years. Between 40 and 50 years of age mammograms are recommended every other year. After age 50 years, yearly mammograms are recommended.

Breathing: The process of respiration, during which air is inhaled into the lungs through the mouth or nose due to muscle contraction, and then exhaled due to muscle relaxation.

C

CA 19-9: A tumor marker initially found in colorectal cancer patients, but subsequently also identified in patients with pancreatic, stomach, and bile duct cancer. In those who have pancreatic cancer, higher levels of CA 19-9 tend to be associated with more advanced disease. Noncancerous conditions that may elevate CA 19-9 levels include gallstones, pancreatitis, cirrhosis of the liver, and cholecystitis.

Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread).

Cancer causes: In most individual cases of cancer, the exact cause of cancer is unknown. The causes may include increased genetic susceptibility; environmental insults, such as chemical exposure or smoking cigarettes; lifestyle factors, including diet; damage caused by infectious disease; and many more.

Cancer symptoms: Abnormal sensations or conditions that persons can notice that are a result of a cancer. It is important to see your doctor for regular checkups and not wait for problems to occur. But you should also know that the following symptoms may be associated with cancer: changes in bowel or bladder habits, a sore that does not heal, unusual bleeding or discharge, thickening or lump in the breast or any other part of the body, indigestion or difficulty swallowing, obvious change in a wart or mole, or nagging cough or hoarseness. These symptoms are not always a sign of cancer. They can also be caused by less serious conditions. Only a doctor can make a diagnosis. It is important to see a doctor if you have any of these symptoms. Don't wait to feel pain. Early cancer often does not cause pain.

Carcinogenic: Causing cancer or contributing to the causation of cancer. Pertaining to a carcinogen.

Carcinoma: Cancer that begins in the skin or in tissues that line or cover body organs. For example, carcinoma can arise in the breast, colon, liver, lung, prostate, and stomach.

Cell: The basic structural and functional unit in people and all living things. Each cell is a small container of chemicals and water wrapped in a membrane.

Central nervous system (CNS): Pertaining to the brain, cranial nerves and spinal cord.

Cerebellopontine Angle: The angle between the cerebellum and the pons, a common site for the growth of acoustic neuromas (vestibular schwanomas).

Cerebellum: The second largest area of the brain, consisting of two hemispheres or halves and is connected to the brain stem.

Cerebral: Refers to the cerebrum or cerebral hemispheres.

CerebrumL: The largest area of the brain occupying the uppermost part of the skull. It consists of two halves called hemispheres. Each half of the cerebrum is further divided into four lobes: frontal, temporal, parietal, and occipital.

Chemotherapy: 1. In the original sense, a chemical that binds to and specifically kills microbes or tumor cells. The term chemotherapy was coined in this regard by Paul Ehrlich (1854-1915).

Chest X-ray: Commonly used to detect abnormalities in the lungs, but can also detect abnormalities in the heart, aorta, and the bones of the thoracic area. Metallic objects, such as jewelry are removed from the chest and neck areas for a chest x-ray to avoid interference with x-ray penetration and improve accuracy of the interpretation

Chondroma: A rare, benign tumor arising at the base of the skull, especially in the area near the pituitary gland. It is very slow growing and might be present for a long time before causing any symptoms.

Chondrosarcoma: This very rare tumor arises from bone and is composed of cartilage. It is a locally invasive malignant tumor.

Chordoma: A rare, benign, slow growing tumor that occurs at the base of the skull in about 1/3 of patients or at the end of the spine. 

Circumscribed or encapsulated: Localized; having a border or being wholly confined to a specific area.

Circulatory: Having to do with the circulation, the movement of fluid in a regular or circuitous course. Although the adjective "circulatory" need not necessarily refer to the circulation of the blood, for all practical purposes today it does. A circulatory problem is taken usually to be a problem with the blood circulation, for example with heart failure.

Cisplatin: An anticancer drug that belongs to the family of drugs called platinum compounds. Cisplatin is used in the treatment of a wide range of malignancies, including advanced cancer of the ovary, testis, and bladder. Cisplatin is given intravenously. Its full chemical name is cis-dichlorodiammineplatinum. 

Clinical trials: Trials to evaluate the effectiveness and safety of medications or medical devices by monitoring their effects on large groups of people. 

Colon cancer: A malignancy that arises from the inner lining of the colon. Most, if not all, of these cancers develop from colonic polyps. Removal of these precancerous polyps can prevent colon cancer. 

Complementary medicine: A group of diagnostic and therapeutic disciplines that are used together with conventional medicine. An example of a complementary therapy is using aromatherapy to help lessen a patient's discomfort following surgery. 

Computerized tomography: Pictures of structures within the body created by a computer that takes the data from multiple X-ray images and turns them in pictures.

Contrast: Short for "contrast media." Contrast media are X-ray dyes used to provide contrast, for example, between blood vessels and other tissue.

Craniopharyngioma: A benign tumor arising from small nests of cells located near the pituitary stalk.

Craniotomy: Surgery involving the removal of skull bone to gain access to the brain and the bone is put back at the end of the operation.

CT scan: Computerized tomography scan. Pictures of structures within the body created by a computer that takes the data from multiple X-ray images and turns them into pictures on a screen. CT stands for computerized tomography.

Cyst: A fluid-filled mass, usually enclosed by a membrane

Cytology: The medical and scientific study of cells. Cytology refers to a branch of pathology, the medical specialty that deals with making diagnoses of diseases and conditions through the examination of tissue samples from the body.

D

Diabetes: Refers to diabetes mellitus or, less often, to diabetes insipidus. Diabetes mellitus and diabetes insipidus share the name "diabetes" because they are both conditions characterized by excessive urination (polyuria).

Diagnosis: 1 The nature of a disease; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies. 3 The identification of any problem. The diagnosis was a plugged tube.

Diarrhea: A familiar phenomenon with unusually frequent or unusually liquid bowel movements, excessive watery evacuations of fecal material. The opposite of constipation. The word "diarrhea" with its odd spelling is a near steal from the Greek "diarrhoia" meaning "a flowing through." Plato and Aristotle may have had diarrhoia while today we have diarrhea. There are myriad infectious and noninfectious causes of diarrhea. 

Differentiation: 1 The process by which cells become progressively more specialized; a normal process through which cells mature. This process of specialization for the cell comes at the expense of its breadth of potential. Stem cells can, for example, differentiate into secretory cells in the intestine. 2 In cancer, differentiation refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread at a slower rate than undifferentiated or poorly differentiated tumor cells, which lack the structure and function of normal cells and grow uncontrollably.

Diffuse : Lacking a distinct border, spread out, not localized.

DNA: Deoxyribonucleic acid. One of two types of molecules that encode genetic information. (The other is RNA. In humans DNA is the genetic material; RNA is transcribed from it. In some other organisms, RNA is the genetic material and, in reverse fashion, the DNA is transcribed from it).

Drain: A device for removing fluid from a cavity or wound. A drain is typically a tube or wick. As a verb, to allow fluid to be released from a confined area.

Duct: A passage or a tube with well-defined walls suitable for the conveyance of air or liquids, as the bile duct and the pancreatic duct.

E

Ear: The hearing organ. There are three sections of the ear, according to the anatomy textbooks. They are the outer ear (the part we see along the sides of our head behind the temples), the middle ear, and the inner ear. But in terms of function, the ear has four parts: those three and the brain. Hearing thus involves all parts of the ear as well as the auditory cortex of the brain. The external ear helps concentrate the vibrations of air on the ear drum and make it vibrate. These vibrations are transmitted by a chain of little bones in the middle ear to the inner ear. There they stimulate the fibers of the auditory nerve to transmit impulses to the brain.

EGFR: Epidermal growth factor receptor. A protein found on the surface of cells to which epidermal growth factor (EGF) binds. When EGF attaches to EGFR, it activates the enzyme tyrosine kinase, triggering reactions that cause the cells to grow and multiply. EGFR is found at abnormally high levels on the surface of many types of cancer cells, which may divide excessively in the presence of EGF. The drug Iressa attaches to EGFR and thereby inhibits the attachment of EGF and stops cell division. The gene for EGFR is on chromosome 7p12.3-p12.1. The EGFR molecule has 3 regions -- one projects outside the cell and contains the site for binding EGF; the second is embedded in the cell membrane; and the third projects into the cytoplasm of the cell's interior. EGFR is a kinase that attaches phosphate groups to tyrosine residues in proteins. EGFR is also known confusingly as ErbB1, ErbB, oncogene ErbB, and HER1. 

Encapsulated: Localized. Refers to a tumor that is wholly confined to a specific area, surrounded by a capsule.

Endocrine: Pertaining to hormones and the glands that make and secrete them into the bloodstream through which they travel to affect distant organs. The endocrine sites include the hypothalamus, pituitary gland, pineal gland, thyroid, parathyroids, heart (which makes atrial-natriuretic peptide), the stomach and intestines, islets of Langerhans in the pancreas, the adrenal glands, the kidney (which makes renin, erythropoietin, and calcitriol), fat cells (which make leptin). the testes, the ovarian follicle (estrogens) and the corpus luteum in the ovary). Endocrine is as opposed to exocrine. (The exocrine glands include the salivary glands, sweat glands and glands within the gastrointestinal tract).

Exocrine: Pertaining to the secretion of a substance out through a duct. The exocrine glands include the salivary glands, sweat glands and glands within the gastrointestinal tract. Exocrine is as opposed to endocrine which refers to the secretion of a substance (a hormone) into the bloodstream. The exocrine glands are the "glands of external secretion" while the endocrine glands are "glands of internal secretion.

External radiation therapy: Radiation therapy using a machine located outside the body to aim high-energy rays at a tumor.

F

Family history: The family structure and relationships within the family, including information about diseases in family members.

Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency of accomplishment, usually accompanied by a feeling of weariness and tiredness. Fatigue can be acute and come on suddenly or chronic and persist.

Fine needle aspiration: The use of a thin needle to withdraw material from the body. For example, this method is commonly used to determine whether a nodule in the thyroid gland is benign or malignant (fine needle aspiration biopsy of the thyroid). A fine gauge needle is placed into the nodule and a drop of blood is withdrawn. The cells are studied under the microscope by an pathologist. 

Fractionated Stereotactic Radiosurgery. Also known as stereotactic radiotherapy, this treatment involves smaller doses of radiation delivered in multiple sessions over time. The doses are administered using a Linear Accelerator (LINAC) machine and may also use state-of-the-art Shaped Beam™ Surgery capabilities. Patients undergoing this treatment typically come in once a day, five days a week for five or six weeks. 

Focal : Limited to one specific area.

FSR or SRT (Fractionated Stereotactic Radiotherapy): A moderately high dose radiation treatment usually received over three to eight sessions.

G

Gallbladder: A pear-shaped organ just below the liver that stores the bile secreted by the liver. During a fatty meal, the gallbladder contracts, delivering the bile through the bile ducts into the intestines to help with digestion. Abnormal composition of bile leads to formation of gallstones, a process termed cholelithiasis. The gallstones cause cholecystitis, inflammation of the gallbladder.

Gamma Knife. The first kind of radiation machine capable of applying stereotactic radiosurgery. For Gamma Knife surgery, the patient wears a lightweight stereotactic head frame during diagnostic scans and the actual radiation treatment. This helps ensure that radiation is pinpointed to the tumor and does not damage any surrounding healthy tissue.

Ganglia: A mass of nerve tissue or a group of nerve cell bodies.

Germ cell: The eggs and sperm are the germ cells: the reproductive cells. Each mature germ cell is haploid in that it has a single set of 23 chromosomes containing half the usual amount of DNA and half the usual number of genes.

Germ cell tumor: A tumor that arise from a germ cell. These tumors may arise within the gonads -- the ovary and testis. Most testicular tumors are, in fact, germ cell tumors. Germ cell tumors also occur in sites outside the gonads, reflecting the fact that germ cells travel to diverse areas of the body, such as the chest, abdomen, and brain.

Gland: 1. A group of cells that secrete a substance for use in the body. For example, the thyroid gland. 2. A group of cells that removes materials from the circulation. For example, a lymph gland. 

Gleason score: A grading system for prostate carcinoma devised by Dr. Donald Gleason in 1977 as a method for predicting the behavior of prostate cancer. 

Glial Tissue/Cells: The supportive tissue of the brain. The most common cells are astrocytes and oligodendrocytes. Unlike nerves, glial can reproduce itself. Glial is the origin of the largest percentage of brain tumors.

Glioblastoma Multiforme (GBM): A malignant tumor which commonly invades adjacent tissue and spreads throughout the CNS. This is usually a fast growing tumor containing a mixture of cell types.

Glioma: A brain tumor that begin in a glial, or supportive, cell, in the brain or spinal cord. Malignant gliomas are the most common primary tumors of the central nervous system (the brain and spinal cord). 

Glomus Jugulare : A very rare, slow growing, benign tumor that invades the temporal bone.

H

Hair loss: Hair loss is the thinning of hair on the scalp. The medical term for hair loss is alopecia. Alopecia can be temporary or permanent. The most common form of hair loss occurs gradually and is referred to as "androgenetic alopecia," meaning that a combination of hormones (androgens are male hormones) and heredity (genetics) is needed to develop the condition. Other types of hair loss include alopecia areata (patches of baldness that usually grow back), telogen effluvium (rapid shedding after childbirth, fever, or sudden weight loss); and traction alopecia (thinning from tight braids or ponytails). 

Headache: A pain in the head with the pain being above the eyes or the ears, behind the head (occipital), or in the back of the upper neck. Headache, like chest pain or back ache, has many causes.

Hemoptysis: Spitting or coughing up blood or bloody-stained sputum. Pronounced he-MOP-ti-sis.

Hemangioblastoma: A benign tumor-like mass arising from blood vessels and is often cystic. It is often associated with von Hippel-Lindau disease.

Hemangiopericytoma: A rare tumor, grade II or grade III, different from the meningioma, although rising from the same cells.

Hemiparesis: Muscle weakness of one side of the body.

Hemiplegia: Complete paralysis of one side of the body. 

Hepatic: Having to do with the liver. Pronounced hi-'pa-tik. From the Latin hepaticus derived from the Greek hepar meaning (not too surprisingly) the liver.

Hepatic artery: An artery that distributes blood to the liver, pancreas and gallbladder as well as to the stomach and duodenal portion of the small intestine.

Hepatic vein: One of the veins which drains blood from the liver.

Hepatitis: Inflammation of the liver from any cause.

Hepatitis B: Inflammation of the liver due to the hepatitis B virus (HBV), once thought to be passed only through blood products. It is now known that hepatitis B can also be transmitted via needle sticks, body piercing and tattooing using un sterilized instruments, the dialysis process, sexual and even less intimate close contact, and childbirth. Symptoms include fatigue, jaundice, nausea, vomiting, dark urine, light stools. Diagnosis is by blood test. Treatment is via anti-viral drugs and/or hepatitis B immunoglobulin (HBIG). 

Hepatitis C: Inflammation of the liver due to the hepatitis C virus (HCV), which is usually spread by blood transfusion, hemodialysis, and needle sticks. HCV causes most transfusion-associated hepatitis, and the damage it does to the liver can lead to cirrhosis and cancer. Transmission of the virus by sexual contact is rare. At least half of HCV patients develop chronic hepatitis C infection. Diagnosis is by blood test. Treatment is via anti-viral drugs. Chronic hepatitis C may be treated with interferon, sometimes in combination with anti-virals. There is no vaccine for hepatitis C. Previously known as non-A, non-B hepatitis. 

Hepatitis C virus: A single-stranded RNA virus in the Flaviviridae family that causes hepatitis C. Abbreviated HCV. The HCV genome contains some 10,000 nucleotides and encodes a single polyprotein of 3,000 amino acids. HCV was discovered in 1989. Before that time, hepatitis C was referred to as non-A, non-B hepatitis. 

Hepatocellular carcinoma: A tumor in which the cancer starts during adulthood in cells in the liver. Also called adult primary liver cancer.

Hepatoma: Cancer originating in the liver, in liver cells. More often called hepatocarcinoma or hepatocellular carcinoma. From hepat-, the liver + -oma, tumor = a liver tumor.

Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs.

Hormone therapy: A form of treatment that takes advantage of the fact that certain cancers depend on hormones to grow. Hormone therapy may include giving hormones to the patient or decreasing the level of hormones in the body.

I

Immune: Protected against infection. The Latin immunis means free, exempt.

Immune system: A complex system that is responsible for distinguishing us from everything foreign to us, and for protecting us against infections and foreign substances. The immune system works to seek and kill invaders. 

Immunosuppression: Suppression of the immune system. Immunosuppression may result from certain diseases such as AIDS or lymphoma or from certain drugs such as some of those used to treat cancer. Immunosuppression may also be deliberately induced with drugs, as in preparation for bone marrow or other organ transplantation to prevent the rejection of the transplant. 

Immunotherapy: Use of the body's immune system to fight tumors.

IMRT (Intensity Modulated Radiation Therapy): The intensity of the radiation can be changed during treatment to spare adjoining normal tissue and increase the dose to the tumor.

Implant: 1. To embed; to set in firmly. In embryology, the fertilized egg implants in the uterine lining 6 or 7 days after conception (fertilization). In medicine today, many things may be implanted. 2. That which is embedded. For example: lens implants, breast implants, cochlear implants, defibrillator implants, pacemaker implants, etc.

Impotence: A common problem among men characterized by the consistent inability to sustain an erection sufficient for sexual intercourse or the inability to achieve ejaculation, or both. Impotence can vary. It can involve a total inability to achieve an erection or ejaculation, an inconsistent ability to do so, or a tendency to sustain only very brief erections.

Incontinence: Inability to control excretions. Urinary incontinence is inability to keep urine in the bladder. Fecal incontinence is inability to retain feces in the rectum.

Incidence: The frequency with which something, such as a disease, appears in a particular population or area. In disease epidemiology, the incidence is the number of newly diagnosed cases during a specific time period. The incidence is distinct from the prevalence which refers to the number of cases alive on a certain date.

Incision: A cut. When making an incision, a surgeon is making a cut.

Indicate: In medicine, to make a treatment or procedure advisable because of a particular condition or circumstance. For example, certain medications are indicated for the treatment of hypertension during pregnancy while others are contraindicated.

Infection: The growth of a parasitic organism within the body. (A parasitic organism is one that lives on or in another organism and draws its nourishment therefrom.) A person with an infection has another organism (a "germ") growing within him, drawing its nourishment from the person.

Infiltrating: Penetrating normal, surrounding tissue.

Inflammation: A basic way in which the body reacts to infection, irritation or other injury, the key feature being redness, warmth, swelling and pain. Inflammation is now recognized as a type of nonspecific immune response.

Inner ear: There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The inner ear is far and away the most highly complex. The essential component of the inner ear for hearing is the membranous labyrinth where the fibers of the auditory nerve (the nerve connecting the ear to the brain) end. The membranous labyrinth is a system of communicating sacs and ducts (tubes) filled with fluid (the endolymph). The membranous labyrinth is lodged within a cavity called the bony labyrinth. At some points the membranous labyrinth is attached to the bony labyrinth and at other points the membranous labyrinth is suspended in a fluid (the perilymph) within the bony labyrinth.

Intracavity: Treatment delivered into the space created when the brain tumor was removed.

Intracranial: Within the cranium, the bony dome that houses and protects the brain.

Interventional radiologist: A radiologist who uses image guidance methods to gain access to vessels and organs. Interventional radiologists can treat certain conditions through the skin (percutaneously) that might otherwise require surgery. The technology includes the use of balloons, catheters, microcatheters, stents, and therapeutic embolization (deliberately clogging up a blood vessel). The specialty of interventional radiology overlaps with other fields, including interventional cardiology, vascular surgery, endoscopy, laparoscopy, and other minimally invasive techniques, such as biopsies. Specialists performing interventional radiology procedures today include not only radiologists but also other types of physicians such as general surgeons, vascular surgeons, cardiologists, gastroenterologists, gynecologists, and urologists.

Invasive: Refers to a tumor that invades healthy tissues; also called diffuse or infiltrating.

Iressa: Brand name for gefitinib, a drug that attaches to the epidermal growth factor receptor (EGFR) on the surfaces of cells . People with non-small-cell lung cancer who have a mutation in the gene for EGFR enjoy a rapid and often dramatic response to the drug. For more information

Irradiation: Radiation therapy; treatment by ionizing radiation.

J

Jaundice: Yellow staining of the skin and sclerae (the whites of the eyes) by abnormally high blood levels of the bile pigment bilirubin. The yellowing extends to other tissues and body fluids. Jaundice was once called the "morbus regius" (the regal disease) in the belief that only the touch of a king could cure it. 

L

Lesion: Pronounced "lee-sion" with the emphasis on the "lee," a lesion can be almost any abnormality involving any tissue or organ due to any disease or any injury.

Lipoma: A rare, benign tumor composed of fat tissue, commonly located in the corpus callosum.

Local: In the area of the tumor; confined to one specific area.

Local treatment: Treatment that affects the tumor and the area close to it.

Linear Accelerator (LINAC). A linear accelerator (LINAC) machine is used to deliver radiation that is generally referred to as high-energy X-ray. LINAC machines can be used to deliver conventional forms of radiation therapy, as well as stereotactic radiosurgery. LINACs are ideal for treating larger tumors and lesions that may not be treatable with single-dose stereotactic radiotherapy. 

Liver: An organ in the upper abdomen that aids in digestion and removes waste products and worn-out cells from the blood. The liver is the largest solid organ in the body. The liver weighs about three and a half pounds (1.6 kilograms). It measures about 8 inches (20 cm) horizontally (across) and 6.5 inches (17 cm) vertically (down) and is 4.5 inches (12 cm) thick. 

Liver biopsy: A procedure in which a small sample of the liver is removed for the diagnosis of abnormal liver conditions. 

Liver disease: Liver disease refers to any disorder of the liver. The liver is a large organ in the upper right abdomen that aids in digestion and removes waste products from the blood. 

Lobe: Part of an organ that appears to be separate in some way from the rest. A lobe may be demarcated from the rest of the organ by a fissure (crack), sulcus (groove), connective tissue or simply by its shape. For example, there are the frontal, parietal, temporal, and occipital lobes of the brain.

Lobectomy: An operation done to remove a lobe of an organ such as the lobe of a lung or a lobe of the thyroid gland.

Lungs: The lungs are a pair of breathing organs located with the chest which remove carbon dioxide from and bring oxygen to the blood. There is a right and left lung. 

M

Magnetic resonance imaging: A special radiology technique designed to image internal structures of the body using magnetism, radio waves, and a computer to produce the images of body structures. In magnetic resonance imaging (MRI), the scanner is a tube surrounded by a giant circular magnet. The patient is placed on a moveable bed that is inserted into the magnet. The magnet creates a strong magnetic field that aligns the protons of hydrogen atoms, which are then exposed to a beam of radio waves. This spins the various protons of the body, and they produce a faint signal that is detected by the receiver portion of the MRI scanner. A computer processes the receiver information, and an image is produced. The image and resolution is quite detailed and can detect tiny changes of structures within the body, particularly in the soft tissue, brain and spinal cord, abdomen and joints.

Malignancy: A tumor that is malignant, that is cancerous, that can invade and destroy nearby tissue, and that may spread (metastasize) to other parts of the body.

Malignant: 1. Tending to be severe and become progressively worse, as in malignant hypertension. 2. In regard to a tumor, having the properties of a malignancy that can invade and destroy nearby tissue and that may spread (metastasize) to other parts of the body. Cancerous or life-threatening, tending to become progressively worse.

 Medical history: 1. In clinical medicine, the patient's past and present which may contain clues bearing on their health past, present, and future. The medical history, being an account of all medical events and problems a person has experienced, including psychiatric illness, is especially helpful when a differential diagnosis is needed.

Medulloblastoma (MDL): A type of brain tumor that tends to occur in children, arise in the cerebellum (in the lower part of the brain), and spread along the spine.

Melanoma: The most dangerous form of skin cancer, a malignancy of the melanocyte, the cell that produces pigment in the skin. Melanoma is most common in people with fair skin, but can occur in people with all skin colors. Most melanomas present as a dark, mole-like spot that spreads and, unlike a mole, has an irregular border. The tendency toward melanoma may be inherited, and the risk increases with overexposure to the sun and sunburn.

Memory: 1. The ability to recover information about past events or knowledge. 2. The process of recovering information about past events or knowledge. 3. Cognitive reconstruction. The brain engages in a remarkable reshuffling process in an attempt to extract what is general and what is particular about each passing moment. 

Meningioma: A common type of slow growing, usually benign brain tumor that arises from the dura, one of the meninges, the membranes covering the brain and spinal cord. A meningioma may occur wherever there is dura but the most common sites are over the cerebral hemispheres of the brain. It is the only brain tumor that is more common in women than men. It tends to occur between 40 and 60 but can occur at any age. Meningiomas may be multiple. Very rarely do they become malignant. The symptoms depend on the location of the tumor.

Mesothelioma: A malignant tumor of the mesothelium. The mesothelium is the thin lining on the surface of the body cavities and the organs that are contained within them. Most mesotheliomas begin as one or more nodules that progressively grow to form a solid coating of tumor surrounding the lung, abdominal organs, or heart.

Metastasis: 1. The process by which cancer spreads from the place at which it first arose as a primary tumor to distant locations in the body. 2. The cancer resulting from the spread of the primary tumor. For example, someone with melanoma may have a metastasis in their brain. And a person with colon cancer may, fortunately, show no metastases.

Metastasize: The spread from one part of the body to another. When cancer cells metastasize and cause secondary tumors, the cells in the metastatic tumor are like those in the original cancer.

Middle ear: There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The middle ear consists of the ear drum (the tympanum or tympanic membrane) and, beyond it, a cavity. This cavity is connected via a canal (the Eustachian tube) to the pharynx (the nasopharynx). The Eustachian tube permits the gas pressure in the middle ear cavity to adjust to external air pressure (so, as you're descending in a plane, it's the Eustachian tube that opens when your ears "open"). The middle ear cavity also contains a chain of 3 little bones (ossicles) that connect the ear drum to the internal ear. The ossicles are named (not the Nina, the Pinta and the Santa Maria, but) the malleus, incus, and stapes. In terms of function, the middle ear communicates with the pharynx, equilibrates with external pressure and transmits the ear drum vibrations to the inner ear. %3