GLOSSARY

A

ABSCESS.

A localized collection of pus or infection that is walled off from the rest of the body.

ABSENCE SEIZURE.

A type of generalized seizure in which the person may temporarily appear to be staring into space and/or have jerking or twitching muscles. Previously called a petit mal seizure.

ABSTRACTION.

Ability to think about concepts or ideas separate from specific examples.

ACALCULIA.

The inability to perform basic calculation (addition, subtraction, multiplication, division).

ACETYLCHOLINE.

A chemical called a neurotransmitter that functions primarily to mediate activity of the nervous system and skeletal muscles.

ACHALASIA.

An esophageal disease of unknown cause in which the lower sphincter muscle is unable to relax normally, resulting in obstruction, either partial or complete.

ACOUSTIC.

A term that refers to hearing.

ACOUSTIC NERVE.

The cranial nerve VIII, involved in both hearing and balance.

ACROPARESTHESIAS.

Painful burning sensation in hands and feet.

ACTION POTENTIAL.

The wave-like change in the electrical properties of a cell membrane, resulting from the difference in electrical charge between the inside and outside of the membrane.

ACUITY.

Sharpness.

ADJUVANT.

A medication or other substance given to aid another drug, such as a tranquilizer given to ease the anxiety of a cancer patient in addition to an analgesic for pain relief.

ADRENAL INSUFFICIENCY.

Problems with the adrenal glands that can be life-threatening if not treated. Symptoms include sluggishness, weakness, weight loss, vomiting, darkening of the skin, and mental changes.

ADVANCED BONE AGE.

The bones, on x ray, appear to be those of an older individual.

AFFECTIVE PSYCHOSIS.

Abnormalities in mood, emotions, feelings, sensibility, or mental state.

AFLATOXIN.

A toxin produced by a fungus that infests grains, peanuts, soybeans, and corn that have been stored in warm, moist conditions.

AGNOSIA.

Inability to notice or process sensory stimuli.

AGRAPHIA.

The inability to write.

AIDS.

Acquired Immune Deficiency Syndrome is a sexually transmitted disease caused by the Human Immunodeficiency Virus (HIV). It weakens the immune system and makes a person susceptible to many infections and malignancies.

ALEXANDER TECHNIQUE.

A form of movement therapy that emphasizes correct posture and the proper positioning of the head with regard to the spine.

ALGORITHMS.

A sequence of steps designed to calculate or determine a task.

ALLERGEN.

Any substance that irritates only those who are sensitive (allergic) to it.

ALZHEIMER DISEASE.

A neurological disorder characterized by slow, progressive memory loss due to a gradual loss of brain cells.

AMAUROSIS FUGAX.

A type of transient ischemic attack (TIA) caused by decreased blood flow through the carotid artery, characterized by blindness or decreased vision in one eye.

AMENORRHEA.

The absence or abnormal stoppage of menstrual periods.

AMINO ACID.

An organic compound composed of both an amino group and an acidic carboxyl group. Amino acids are the basic building blocks of proteins. There are 20 types of amino acids (eight are "essential amino acids" that the body cannot make and must therefore be obtained from food).

AMNESIA.

A general medical term for loss of memory that is not due to ordinary forgetfulness. Amnesia can be caused by head injuries, brain disease, or epilepsy, as well as by dissociation. Includes: 1) Anterograde amnesia: inability to retain the memory of events occurring after the time of the injury or disease that brought about the amnesic state. 2) Retrograde amnesia: inability to recall the memory of events that occurred prior to the time of the injury or disease that brought about the amnesic state.

AMNIOCENTESIS.

A procedure performed at 16-18 weeks of pregnancy in which a needle is inserted through a woman's abdomen into her uterus to draw out a small sample of the amniotic fluid from around the baby. Either the fluid itself or cells from the fluid can be used for a variety of tests to obtain information about genetic disorders and other medical conditions in the fetus.

AMNIOTIC FLUID.

The fluid that surrounds a developing baby during pregnancy.

AMNIOTIC SAC.

Contains the fetus, which is surrounded by amniotic fluid.

AMYGDALA.

An almond-shaped brain structure in the limbic system that is activated in stressful situations to trigger the emotion of fear. Hallucinations related to posttraumatic stress are thought to be caused by the activation of memory traces in the amygdala that have not been integrated and modified by other parts of the brain.

AMYLOID PLAQUE.

A waxy, translucent, starch-like protein that is deposited in tissues during the course of certain chronic diseases such as rheumatoid arthritis and Alzheimer disease.

AMYLOIDOSIS.

The accumulation of amyloid deposits in various organs and tissues in the body so that normal functioning is compromised. Primary amyloidosis usually occurs as a complication of multiple myeloma. Secondary amyloidosis occurs in patients suffering from chronic infections or inflammatory diseases such as tuberculosis, rheumatoid arthritis, and Crohn's disease.

AMYOTROPHIC LATERAL SCLEROSIS.

ALS, also called Lou Gehrig's disease is a progressive neuromuscular condition due to degeneration of the motor nerve cells and fiber tracts in the spinal cord. The cause is not yet well defined. It is characterized by progressive weakening of the limb muscles and those involved in swallowing and breathing. It is fatal within a couple of years of onset.

AMYOTROPHY.

A type of neuropathy resulting in pain, weakness, and/or wasting in the muscles.

ANAEROBIC.

Describes an organism that grows and thrives in an oxygen-free environment.

ANALGESICS.

A class of pain-relieving medicines, including aspirin and Tylenol.

ANEMIA.

A condition in which there is an abnormally low number of red blood cells in the bloodstream. It may be due to loss of blood, an increase in red blood cell destruction, or a decrease in red blood cell production. Major symptoms are paleness, shortness of breath, unusually fast or strong heart beats, and tiredness.

ANEURYSM.

A weakened area in the wall of a blood vessel that causes an outpouching or bulge. Aneurysms may be fatal if these weak areas burst, resulting in uncontrollable bleeding.

ANGINA PECTORIS.

Chest pain caused by an insufficient supply of oxygen and decreased blood flow to the heart muscle. Angina is frequently the first sign of coronary artery disease.

ANGIOFIBROMA.

Non-cancerous growth of the skin, which are often reddish in color and filled with blood vessels.

ANGIOGRAPHY.

A mapping of the brain's blood vessels, using x-ray imaging.

ANGIOKERATOMA.

Skin rash comprised of red bumps. Rash most commonly occurs between the navel and the knees.

ANGIOMYOLIPOMA.

Non-cancerous growth in the kidney, most often found in tuberous sclerosis.

ANGULAR GYRUS.

A ridge (outfolding) in the parietal lobe of the brain.

ANNULUS FIBROSUS.

A fibrous and cartilage ring that forms the circumference of a vertebrae.

ANOREXIA.

Loss of appetite.

ANOXIA.

Lack of oxygen.

ANTERIOR CIRCULATION.

The blood supply to most of the front part of the brain known as the cerebrum, including the frontal, parietal, and temporal lobes.

ANTERIOR VITREITIS.

Inflammation of the corpus vitreum, which surrounds and fills the inner portion of the eyeball between the lens and the retina.

ANTEROGRADE AMNESIA.

Amnesia for events that occurred after a physical injury or emotional trauma but before the present moment.

ANTIBODY.

A special protein made by the body's immune system as a defense against foreign material (bacteria, viruses, etc.) that enters the body. It is uniquely designed to attack and neutralize the specific antigen that triggered the immune response.

ANTICHOLINERGIC DRUGS.

Drugs that block the action of the neurotransmitter acetylcholine. They are used to lessen muscle spasms in the intestines, lungs, bladder, and eye muscles.

ANTICIPATION.

Genetic phenomenon in which a triple repeat DNA mutation expands in a future generation, causing symptoms to develop earlier.

ANTICONVULSANT DRUGS.

Drugs used to prevent convulsions or seizures. They often are prescribed in the treatment of epilepsy.

ANTIEMETIC.

A type of drug given to stop vomiting.

ANTIEPILEPTIC.

A drug that prevents or limits the spread of epileptic seizures.

ANTIGEN.

A substance (usually a protein) identified as foreign by the body's immune system, triggering the release of antibodies as part of the body's immune response.

ANTIOXIDANT.

Any substance that reduces the damage caused by oxidation, such as the harm caused by free radicals.

ANTIPLATELET AGENTS.

Drugs that reduce the tendency of platelets to clump together, used to reduce the risk of transient ischemic attack (TIA) or stroke.

ANTIVIRAL.

A drug that prevents viruses from replicating and therefore spreading infection.

ANXIETY.

Worry or tension in response to real or imagined stress, danger, or dreaded situations. Physical reactions such as fast pulse, sweating, trembling, fatigue, and weakness may accompany anxiety.

ANXIETY DISORDER.

A psychiatric disorder involving the presence of anxiety that is so intense or so frequently present that it causes difficulty or distress for the individual.

AORTA.

The major artery that carries oxygenated blood from the heart to be delivered by arteries throughout the body.

APHASIA.

Loss of the ability to speak or to understand written or spoken language. A person who cannot speak or understand language is said to be aphasic.

APHERESIS.

A procedure in which the blood is removed and filtered in order to rid it of particular cells, then returned to the patient.

APNEA.

An irregular breathing pattern characterized by abnormally long periods of the complete cessation of breathing.

APRAXIA.

Inability to carry out ordinary purposeful movements in the absence of paralysis.

ARACHNOID MEMBRANE.

One of the three membranes that sheath the spinal cord and brain; the arachnoid is the middle membrane. Also called the arachnoid mater.

ARBOVIRUSES.

Viruses harbored by arthropods (mosquitoes and ticks) and transferred to humans by their bite. An arbovirus is the cause of West Nile infection, and arboviruses are one cause of encephalitis.

AREFLEXIA.

Absence of a reflex; a sign of possible nerve damage.

ARTERIOGRAM.

An x-ray study of an artery that has been injected with a contrast dye.

ARTERIOSCLEROSIS.

A chronic condition characterized by thickening and hardening of the arteries and the build-up of plaque on the arterial walls. Arteriosclerosis can slow or impair blood circulation.

ARTERIOVENOUS MALFORMATION.

Abnormal, direct connection between the arteries and veins. Arteriovenous malformations can range from very small to large.

ASPERGER SYNDROME.

A developmental disorder of childhood characterized by autistic behavior but without the same difficulties acquiring language that children with autism have.

ASPIRATION.

Inhalation of food or liquids into the lungs.

ASPIRATION PNEUMONIA.

Infection of the lungs, caused by the presence of foreign material such as food.

ASTHENIA.

Muscle weakness.

ASTHMA.

A disease in which the air passages of the lungs become inflamed and narrowed.

ASTROCYTES.

Types of neuroglial cells in the central nervous system that help support other nerve cells.

ATAXIA.

A condition marked by impaired muscular coordination, most frequently resulting from disorders in the brain or spinal cord.

ATHEROSCLEROTIC PLAQUE.

A deposit of fatty and calcium substances that accumulate in the lining of the artery wall, restricting blood flow. The disease is called atherosclerosis.

ATHETOSIS.

A condition marked by slow, writhing, involuntary muscle movements.

ATONIC SEIZURE.

A seizure characterized by a sudden loss of muscle tone, causing the individual to fall to the floor.

ATRIAL FIBRILLATION.

A type of heart arrhythmia in which the upper chamber of the heart quivers instead of pumping in an organized way. In this condition, the upper chambers (atria) of the heart do not completely empty when the heart beats, which can allow blood clots to form.

ATROPHY.

The progressive wasting and loss of function of any part of the body.

AUDIOLOGIST.

A healthcare professional who specializes in diagnostic testing of hearing impairments and rehabilitation of patients with hearing problems.

AUDITORY.

Pertaining to the sense of hearing.

AUDITORY NERVE.

A bundle of nerve fibers that carries hearing information between the cochlea and the brain.

AURA.

A group of visual or other sensations that precedes the onset of a migraine attack.

AUTISM.

A developmental disability that appears early in life, in which normal brain development is disrupted and social and communication skills are retarded, sometimes severely.

AUTISTIC PSYCHOPATHY.

Hans Asperger's original name for the condition now known as Asperger's disorder. It is still used occasionally as a synonym for the disorder.

AUTOANTIBODIES.

Antibodies that attack the body's own cells or tissues.

AUTOIMMUNE.

Pertaining to an immune response by the body against its own tissues or types of cells.

AUTOIMMUNE DISEASE.

One of a group of diseases, like rheumatoid arthritis and systemic lupus erythematosus, in which the immune system is overactive and has lost the ability to distinguish between self and non-self. The body's immune cells turn on the body, attacking various tissues and organs.

AUTOMATISMS.

Movements during a seizure that are semi-purposeful but involuntary.

AUTONOMIC FAILURE.

Refers to failure in the autonomic nervous system, which comprises two divisions called the parasympathetic nervous system, which slows heart rate, increases intestinal and gland activity, and relaxes sphincter muscles; and the sympathetic nervous system, which accelerates heart rate, raises blood pressure, and constricts blood vessels.

AUTONOMIC NERVOUS SYSTEM.

The part of the nervous system that controls so-called involuntary functions, such as heart rate, salivary gland secretion, respiratory function, and pupil dilation.

AUTOSOMAL.

Relating to any chromosome besides the X and Y sex chromosomes. Human cells contain 22 pairs of autosomes and one pair of sex chromosomes.

AUTOSOMAL DOMINANT.

A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. A person with an autosomal dominant disorder has a 50% chance of passing it to each of their offspring.

AUTOSOMAL RECESSIVE.

A pattern of inheritance in which both copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. When both parents have one abnormal copy of the same gene, they have a 25% chance with each pregnancy that their offspring will have the disorder.

AXILLARY.

Referring to the armpit.

AXON.

The long, hairlike extension of a nerve cell that carries a message to a nearby nerve cell.

AXONTOMESIS.

Loss of the protective sheet of tissue that covers the axon (the part of the nerve cell that carries a transmission).

B

BABESIOSIS.

A disease caused by protozoa of the genus Babesia characterized by a malaria-like fever, anemia, vomiting, muscle pain, and enlargement of the spleen. Babesiosis, like Lyme disease, is carried by a tick.

BACILLUS.

A rod-shaped bacterium, such as the diphtheria bacterium.

BALANCED CHROMOSOME TRANSLOCATION.

A rearrangement of the chromosomes in which two chromosomes have broken and exchanged pieces without the loss of genetic material.

BALLISMUS.

Involuntary violent flinging movements that may take the form of uncontrollable flailing. It is also called ballism. Ballismus that occurs with chorea is known as choreoballismus or choreoballism.

BARBITURATE.

A class of drugs including phenobarbital that have sedative properties and depress respiratory rate, blood pressure, and nervous system activity.

BASAL GANGLIA.

Brain structure at the base of the cerebral hemispheres involved in controlling movement.

BASILAR MIGRAINE.

A type of migraine with aura that involves the basilar artery at the base of the brain. It occurs most commonly in young women, and may include vision problems, confusion, and loss of consciousness as well as headache.

BATTERY.

A number of separate items (such as tests) used together. In psychology, a group or series of tests given with a common purpose, such as personality assessment or measurement of intelligence.

BEHAVIOR DISORDERS.

Disorders characterized by disruptive behaviors such as conduct disorder, oppositional defiant disorder, and attention-deficit/hyperactivity disorder.

BENIGN.

In medical usage, benign is the opposite of malignant. It describes an abnormal growth that is stable, treatable, and generally not life-threatening.

BENZODIAZEPINES.

A class of drugs with hypnotic, antianxiety, anticonvulsive, and muscle-relaxant properties. They are used in the treatment of anxiety and sleeping disorders, to relax muscles, and to control seizures. Diazepam (Valium), alprazolam (Xanax), and chlordiazepoxide (Librium) are all benzodiazepines.

BILATERAL.

Occurring on both sides of the body.

BIOCHEMICAL TESTING.

Measuring the amount or activity of a particular enzyme or protein in a sample of blood or urine or other tissue from the body.

BIOFEEDBACK.

A training technique that enables an individual to gain some element of control over involuntary or automatic body functions.

BIOLOGICAL MARKER.

An indicator or characteristic trait of a disease that facilitates differential diagnosis (the process of distinguishing one disorder from other, similar disorders).

BIOPSY.

The surgical removal and microscopic examination of living tissue for diagnostic purposes or to follow the course of a disease. Most commonly the term refers to the collection and analysis of tissue from a suspected tumor to establish malignancy.

BIOTRANSFORMATION.

The conversion of a compound from one form to another by the action of enzymes in the body of an organism.

BIPOLAR DISORDER.

A psychiatric disorder marked by alternating episodes of mania and depression. Also called bipolar illness, manic-depressive illness.

BLOOD VESSELS.

General term for arteries, veins, and capillaries that transport blood throughout the body.

BODYWORK.

Any technique involving hands-on massage or manipulation of the body.

BOLUS.

A mass of a substance to be swallowed.

BOTULINUM TOXIN.

A potent bacterial toxin or poison made by Clostridium botulinum; causes paralysis in high doses, but is used medically in small, localized doses to treat disorders associated with involuntary muscle contraction and spasms, in addition to strabismus. Commonly known as Botox.

BRACHIAL PLEXUS.

A group of lower-neck and upper-back spinal nerves supplying the arm, forearm, and hand.

BRADYKINESIA.

Extremely slow movement.

BRAIN STEM.

The part of the brain that is continuous with the spinal cord and controls most basic life functions. It is the last part of the brain that is destroyed by Alzheimer's disease.

BREECH PRESENTATION.

Buttocks presentation during delivery.

BRONCHITIS.

Inflammation of the air passages of the lungs.

BRUIT.

An abnormal sound heard with the stethoscope placed over the carotid artery in the neck, suggesting decreased blood flow through the vessel.

BRUXISM.

Habitual clenching and grinding of the teeth, especially during sleep.

BULBAR MUSCLES.

Muscles of the mouth and throat responsible for speech and swallowing.

C

CALCIFICATION.

A process in which tissue becomes hardened due to calcium deposits.

CAPILLARY BED.

A dense network of tiny blood vessels that enables blood to fill a tissue or organ.

CAPSAICIN.

An alkaloid derived from hot peppers that can be used as a topical anesthetic.

CARBIDOPA.

A drug combined with levodopa to slow the breakdown of the levodopa, used to treat the symptoms of Parkinson's disease.

CARBONIC ANHYDRASE.

An enzyme that shifts the rate of reaction to favor the conversion of carbon dioxide and water into carbonic acid, bicarbonate ions, and free protons.

CARCINOGEN.

A substance known to cause cancer.

CARDIAC TAMPONADE.

A condition in which blood leaking into the membrane surrounding the heart puts pressure on the heart muscle, preventing complete filling of the heart's chambers and normal heartbeat.

CARDIOMYOPATHY.

A disease of the heart muscle that leads to generalized deterioration of the muscle and its pumping ability.

CARDITIS.

Inflammation of the heart tissue.

CAROTID ARTERY.

One of the major arteries supplying blood to the head and neck.

CAROTID ENDARTERECTOMY.

Surgical procedure designed to reduce the accumulation of plaque in the carotid artery and thus, prevent stroke.

CAROTID ULTRASONOGRAPHY.

A painless and harmless test using high-frequency sound waves to determine if there is narrowing or plaque formation in the carotid arteries.

CARPAL TUNNEL SYNDROME.

A condition caused by compression of the median nerve in the carpal tunnel of the hand, characterized by pain.

CARRIER.

A person who possesses a gene for an abnormal trait without showing signs of the disorder. The person may pass the abnormal gene on to offspring.

CATAPLEXY.

A symptom of narcolepsy marked by a sudden episode of muscle weakness triggered by strong emotions. The muscle weakness may cause the person's knees to buckle or the head to drop. In severe cases the patient may become paralyzed for a few seconds to minutes.

CATARACTS.

Abnormal clouding or opacities within the lens of the eye.

CATATONIA.

A fixed, motionless stupor.

CATECHOLAMINES.

Chemicals such as epinephrine, dopa, and norepinephrine; often at high levels in the urine if a pheochromocytoma is present.

CATHETER.

A long, thin, flexible tube used in angiography to inject contrast material into the arteries.

CAUDATE.

A region of gray matter near the lateral ventricle of the brain; also called caudate nucleus.

CENTRAL APNEA.

Abnormal breathing as a result of the medulla being pushed down, such as from an Arnold-Chiari, Type II malformation.

CENTRAL NERVOUS SYSTEM.

The brain, spinal cord and the nerves throughout the body.

CENTRAL SLEEP APNEA.

A less-common form of sleep apnea in which the brain does not properly signal respiratory muscles to begin breathing.

CEPHALALGIA.

The medical term for headache.

CEREBELLAR ATAXIA.

Unsteadiness and lack of coordination caused by a progressive degeneration of the part of the brain known as the cerebellum.

CEREBELLUM.

The part of the brain involved in the coordination of movement, walking, and balance.

CEREBRAL ANEURYSM.

An abnormal, localized bulge in a blood vessel that is usually caused by a congenital weakness in the wall of the vessel.

CEREBRAL COLLATERAL BLOOD FLOW.

Anatomical and physiological mechanisms that allow blood destined for one hemisphere of the brain to crossover and nourish tissue on the other side of the brain when the supply to the other side of the brain is impaired.

CEREBRAL CORTEX.

The thin, convoluted surface of the brain consisting mainly of nerve cell bodies. This brain region is responsible for reasoning, mood, and perception.

CEREBRAL DOMINANCE.

The preeminence of one cerebral hemisphere over the other in the control of cerebral functions.

CEREBRAL EMBOLISM.

A blockage of blood flow through a vessel in the brain by a blood clot that formed elsewhere in the body and traveled to the brain.

CEREBRAL HERNIATION.

Movement of the brain against the skull.

CEREBRAL INFARCTION.

Brain-tissue damage caused by interrupted flow of oxygen to the brain.

CEREBRAL ISCHEMIA.

Lack of oxygen to the brain, which may result in tissue death.

CEREBRAL OXIDATIVE METABOLISM.

Using oxygen to generate energy by complex chemical reactions that occur in brain cells.

CEREBRAL PALSY.

A nonprogressive movement disability caused by abnormal development of or damage to motor control centers of the brain.

CEREBRAL THROMBOSIS.

A blockage of blood flow through a vessel in the brain by a blood clot that formed in the brain itself.

CEREBRAL VASCULAR ACCIDENT.

Damage to brain cells caused by lack of blood flow in the brain from emboli (clots) plaque, or hemorrhage.

CEREBROSPINAL FLUID.

The clear, normally colorless fluid that fills the brain cavities (ventricles), the subarachnoid space around the brain, and the spinal cord and acts as a shock absorber.

CEREBRUM.

The main portion of the brain (and the largest part of the central nervous system), occupying the upper portion of the cranial cavity. It is responsible for higher functions such as speech, thought, vision, and memory.

CERULOPLASMIN.

A protein circulating in the bloodstream that binds with and transports copper.

CERVICAL.

Referring to the neck. Cervical vertebrae are the first 7 bones of the spine.

CHELATION.

The process by which a molecule encircles and binds to a metal and removes it from tissue.

CHEMOTHERAPY.

Chemical medical treatment often used for cancer.

CHOREA.

A term that refers to rapid, jerky, involuntary movements of the limbs or face that characterize several different disorders of the nervous system, including chorea of pregnancy, Huntington's chorea, and Sydenham's chorea.

CHOREA GRAVIDARUM.

Chorea occurring in the early months of pregnancy.

CHORIONIC VILLUS SAMPLING.

A medical procedure done during weeks 10-12 of a pregnancy. A needle is inserted into the placenta and a small amount of fetal tissue is withdrawn for analysis.

CHOROID.

A vascular membrane that covers the back of the eye between the retina and the sclera and serves to nourish the retina and absorb scattered light.

CHOROID PLEXUS.

Specialized cells located in the ventricles of the brain that produce cerebrospinal fluid.

CHROMATIN.

The readily stainable portion of a cell nucleus, consisting of DNA, RNA, and various proteins. It coils and folds itself to form chromosomes during the process of cell division. Rett syndrome (RS) is sometimes described as a chromatin disease.

CHROMOSOME.

A microscopic thread-like structure found within each cell of the human body and consisting of a complex of proteins and DNA. Humans have 46 chromosomes arranged into 23 pairs. Chromosomes contain the genetic information necessary to direct the development and functioning of all cells and systems in the body. They pass on hereditary traits from parents to child (like eye color) and determine whether the child will be male or female. Changes in either the total number of chromosomes or their shape and size (structure) may lead to physical or mental abnormalities.

CHRONIC.

Refers to a disease or condition that progresses slowly but persists or recurs over time.

CIRCLE OF WILLIS.

Also known as the circulus arteriosus; formed by branches of the internal carotid arteries and the vertebral arteries.

CIRRHOSIS.

A chronic degenerative disease of the liver, in which normal cells are replaced by fibrous tissue and normal liver function is disrupted. The most common symptoms are mild jaundice, fluid collection in the tissues, mental confusion, and vomiting of blood. Cirrhosis is associated with portal hypertension and is a major risk factor for the later development of liver cancer. If left untreated, cirrhosis leads to liver failure.

CLAUDICATION.

Cramping or pain in a leg caused by poor blood circulation. This condition is frequently caused by hardening of the arteries (atherosclerosis). Intermittent claudication occurs only at certain times, usually after exercise, and is relieved by rest.

CLAVICLE.

Also called the collarbone. Bone that articulates with the shoulder and the breast bone.

CLEFT PALATE.

A birth defect in which the roof of the mouth (palate) has an abnormal opening (cleft).

CLONIC.

A type of seizure characterized by rhythmic jerking of the arms and legs.

CLOSED HEAD INJURY.

Traumatic brain injury (TBI) in which the head strikes or is struck by an object without breaking the skull.

CLUBFOOT.

Abnormal positioning of the feet and legs, when they are turned inward towards each other.

CLUSTER HEADACHE.

A painful recurring headache associated with the release of histamine from cells.

CLUTTER.

A fluency disorder where speech delivery is either abnormally fast, irregular, or both.

COCHLEA.

A spiral-shaped tubular structure resembling a snail's shell that forms part of the inner ear.

COCHLEAR IMPLANT.

A device used for treating deafness that consists of one or more electrodes surgically implanted inside or outside the cochlea, an organ in the inner ear that transforms sound vibrations in the inner ear into nerve impulses for transmission to the brain.

COGNITIVE DELAY.

Impairment or slowing of the mental processes of thinking and acquiring knowledge.

COLLAGEN.

The main supportive protein of cartilage, connective tissue, tendon, skin, and bone.

COMA.

A decreased level of consciousness with deep unresponsiveness.

COMMAND HALLUCINATION.

A type of auditory hallucination in which the person hears voices ordering him or her to perform a specific act.

COMMUNITY MENTAL HEALTH CENTERS.

Organizations that manage and deliver a comprehensive range of mental health services, education, and outreach to residents of a given community.

COMORBID.

A term used to refer to a disease or disorder that is not directly caused by another disorder but occurs at the same time.

COMPULSION.

A repetitive or stereotyped act or ritual.

CONCUSSION.

Injury to the brain causing a sudden, temporary impairment of brain function.

CONDUCTIVE HEARING LOSS.

A type of medically treatable hearing loss in which the inner ear is usually normal, but there are specific problems in the middle or outer ears that prevent sound from getting to the inner ear in a normal way.

CONGENITAL.

Present at birth.

CONGENITAL MYOPATHY.

Any abnormal condition or disease of muscle tissue that is present at birth; it is characterized by muscle weakness and wasting.

CONNECTIVE TISSUE.

Supportive tissue in the body that joins structures together, lending strength and elasticity.

CONSTRUCTIONAL APRAXIA.

Difficulty or inability to copy a drawing.

CONTRACTURE.

A tightening or shortening of muscles that prevents normal movement of the associated limb or other body part.

CONTRECOUP.

An injury to the brain opposite the point of direct impact.

CONTUSION.

A focal area of swollen and bleeding brain tissue.

CORDOTOMY.

Surgery to relieve pain by destroying bundles of nerve fibers on one or both sides of the spinal cord.

CORNEA.

The clear, dome-shaped outer covering of the eye that lies in front of the iris and pupil. The cornea lets light into the eye.

COROLLARY DISCHARGE.

A mechanism in the brain that allows one to distinguish between self-generated and external stimuli or perceptions.

CORPUS CALLOSUM.

A thick bundle of nerve fibers deep in the center of the forebrain that provides communications between the right and left cerebral hemispheres.

CORPUS STRIATUM.

Region of the brain that contains the caudate nucleus and putamen.

CORTICAL ATROPHY.

A wasting away and decrease in size of the outer portion of the brain, or cerebral cortex.

CORTICOSPINAL TRACT.

A tract of nerve cells that carries motor commands for voluntary body movements from the brain to the spinal cord.

CORTICOSTEROIDS.

A group of hormones produced naturally by the adrenal gland or manufactured synthetically. They are often used to treat inflammation. Examples include cortisone and prednisone.

CORTISOL.

A steroid hormone secreted by the adrenal cortex that is important for maintenance of body fluids, electrolytes, and blood sugar levels. Also called hydrocortisone.

CRANIAL NERVES.

The set of twelve nerves found on each side of the head and neck that control the sensory and muscle functions of the eyes, nose, tongue, face, and throat.

CRANIAL SUTURES.

The fibrous joints (sutures) that hold together the five bones comprising the skull of a newborn.

CRANIOSYNOSTOSIS.

A birth defect of the brain characterized by the premature closure of one or more of the cranial sutures, the fibrous joints between the bones of the skull

CRANIOTOMY.

A surgical procedure in which part of the skull is removed (then replaced) to allow access to the brain.

CRANIUM.

Skull; the bony framework that holds the brain.

CREATININE PHOSPHOKINASE.

A chemical normally found in the muscle fibers that is released into the bloodstream when the muscles undergo damage and breakdown. Testing for it can prove the occurrence of a heart attack or other muscle damage. It used to be called creatine kinase.

CRYOABLATION.

Using very cold temperatures to remove a foreign substance or body.

CRYOTHERAPY.

Using very cold temperatures to treat a disease.

CUTANEOUS.

Relating to the skin.

CYST.

An abnormal sac or enclosed cavity in the body that is filled with liquid or partially solid material. Also refers to a protective, walled-off capsule in which an organism lies dormant.

CYSTADENOMA.

Non-cancerous growth, in which fluid-filled, gas, or semi-solid areas may be present.

CYTOGENETICS.

The branch of biology that combines the study of genetic inheritance with the study of cell structure.

CYTOMEGALOVIRUS (CMV).

A common human virus causing mild or no symptoms in healthy people, but permanent damage or death to an infected fetus, a transplant patient, or a person with HIV.

CYTOPLASM.

The substance within a cell including the organelles and the fluid surrounding the nucleus.

CYTOSKELETON.

A network of filaments that give structure and shape to the cell.

CYTOTOXIC T-CELLS.

A type of white blood cells, T-lymphocytes, that can kill body cells infected by viruses or transformed by cancer.

D

DANDY WALKER MALFORMATION.

A complex structural abnormality of the brain frequently associated with hydrocephalus, or accumulation of excess fluid in the brain. Abnormalities in other areas of the body may also be present. Individuals with Dandy-Walker malformation have varying degrees of mental handicap or none at all.

DECEREBRATE POSTURE.

Stiff, rigid posture indicative of severe damage to brain stem.

DECONDITIONING.

Loss of physical strength or stamina resulting from bed rest or lack of exercise.

DECORTICATE POSTURE.

A stiff, rigid posture indicative of damage to nerve tracts that run between spinal cord and brain.

DEINSTITUTIONALIZATION.

The process of moving people out of mental hospitals into treatment programs or halfway houses in local communities. With this movement, the responsibility for care shifted from large (often governmental) agencies to families and community organizations.

DELIRIUM.

A condition characterized by waxing-andwaning episodes of confusion and agitation.

DELTOID MUSCLE.

A muscle near the clavicle bone that is responsible for arm movement.

DELUSION.

A false belief that a person maintains in spite of obvious proof or evidence to the contrary.

DEMENTIA.

Loss of memory and other higher functions, such as thinking or speech, lasting six months or more.

DEMENTIA PUGILISTICA.

Syndrome of brain damage caused by repeated head trauma. People with this kind of damage are sometimes described as "punch drunk."

DEMYELINATING DISEASES.

A group of diseases characterized by the breakdown of myelin, the fatty sheath surrounding and insulating nerve fibers. This breakdown interferes with nerve function and can result in paralysis. Multiple sclerosis is a demyelinating disorder.

DEMYELINATION.

Disruption or destruction of the myelin sheath, leaving a bare nerve. It results in a slowing or stopping of the impulses that travel along that nerve.

DEPOLARIZATION.

Occurs when a neuron exchanges ions, causing an influx of sodium and calcium inside the cell and an efflux of potassium out of the cell.

DEPOT.

A type of drug preparation and administration that involves the slow, gradual release from an area of the body where the drug has been injected.

DEPRESSED SKULL FRACTURE.

A fracture in which fragments of broken skull press into brain tissue.

DEPRESSION.

A psychiatric disorder in which the mood is low for a prolonged period of time, and feelings of hopelessness and inadequacy interfere with normal functioning.

DEPRESSIVE DISORDER.

A psychiatric disorder of varying degrees characterized by feelings of hopelessness, physical responses such as insomnia, and withdrawal from normal activities.

DERMATOME.

An area of skin that receives sensations through a single nerve root.

DESMIN.

A protein that provides part of the structure to heart, skeletal, and smooth muscle cells.

DEVELOPMENTAL DELAY.

The failure to meet certain developmental milestones such as sitting, walking, and talking at the average age. Developmental delay may indicate a problem in development of the central nervous system.

DEVELOPMENTAL DISABILITIES.

Disabilities that are present from birth and delay or prevent normal development, such as mental retardation or autism.

DIABETES MELLITUS.

The clinical name for common diabetes. It is a chronic disease characterized by the inability of the body to produce or respond properly to insulin, a hormone required by the body to convert glucose to energy.

DIABETIC NEUROPATHY.

A complication of diabetes mellitus in which the peripheral nerves are affected. Diabetic neuropathy is primarily due to metabolic imbalance and secondarily to nerve compression.

DIALYSIS.

Process by which special equipment purifies the blood of a patient whose kidneys have failed.

DIENCEPHALON.

A part of the brain that binds the mesencephalon to the cerebral hemispheres, it includes the thalmus and the hypothalmus. It acts as a relay station for impulses concerning sensation and movement.

DIFFUSE.

Widespread.

DILATATION.

Increasing in caliber.

DIPLOPIA.

Also known as double vision, it is a visual disorder resulting from unequal action of the eye muscles, which causes two images of a single object to be seen.

DISCECTOMY.

Surgery to relieve pressure on a nerve root caused by a bulging disc or bone spur.

DISCOGRAPHY.

A test in which dye is injected into a disc space thought to be causing back pain, allowing the surgeon to confirm that an operation on that disc will be likely to relieve pain.

DISEASE ERADICATION.

A status whereby no further cases of a diseases occur anywhere, and continued control measures are unnecessary.

DISSECTION.

Tear in the wall of an artery that causes blood from inside the artery to leak into the wall and thereby narrows the lumen of the blood vessel.

DISSEMINATED.

Scattered or distributed throughout the body. Lyme disease that has progressed beyond the stage of localized erythema migrans (EM) is said to be disseminated.

DISTAL.

Situated away from the center of the body.

DISTAL MUSCLES.

Muscles farthest away from the center of the body, such as muscles in the fingers and toes.

DIURETIC DRUGS.

A group of medications that increase the amount of urine produced and relieve excess fluid buildup in body tissues. Diuretics may be used in treating high blood pressure, lung disease, premenstrual syndrome, and other conditions.

DIZYGOTIC TWINS.

Twins that share the same environment during development in the uterus.

DNA.

Deoxyribonucleic acid; the genetic material in cells that holds the inherited instructions for growth, development, and cellular functioning.

DNA TESTING.

Analysis of DNA (the genetic component of cells) in order to determine changes in genes that may indicate a specific disorder.

DOMINANT DISORDER.

A disorder resulting from an inheritance pattern where one parent has a single, faulty dominant gene, and has a 50% chance of passing on that faulty gene to offspring with each pregnancy.

DOPAMINE.

A neurotransmitter made in the brain that is involved in many brain activities, including movement and emotion.

DORSAL.

Pertaining in direction to the back or upper surface of an organ.

DORSAL COLUMNS.

This refers to nerve fiber tracts that run in the portion of the spinal cord that is closest to the back. They carry sensory information like position sense and deep pain from the legs and arms to the brain.

DORSAL HORN.

The part of the spinal cord that receives and processes pain messages from the peripheral nervous system.

DOUBLE BLIND STUDY.

A study or clinical trial designed to minimize any bias, in that neither participant or study director knows who is assigned to the control group and who is assigned to the test group until the end of the study.

DOWN SYNDROME.

A genetic disorder characterized by an extra chromosome 21 (trisomy 21), mental retardation, and susceptibility to early-onset Alzheimer's disease.

DUPLICATION.

Extra genetic material due to a duplicate copy.

DURA MATTER.

The strongest and outermost of three membranes that protect the brain, spinal cord, and nerves of the cauda equina.

DYNATOME.

An area in which pain is felt when a given spinal nerve is irritated.

DYSARTHRIA.

Imperfect articulation of speech (slurred speech) due to muscular weakness resulting from damage to the central or peripheral nervous system.

DYSAUTONOMIA.

A disorder or dysfunction of the autonomic nervous system.

DYSCALCULIA.

Difficulty with basic arithmetic and calculations.

DYSESTHESIA.

A painful feeling of numbness, tingling, or heat.

DYSGRAPHIA.

Difficulty writing.

DYSKINESIA.

Impaired ability to make voluntary movements.

DYSLEXIA.

A type of reading disorder often characterized by reversal of letters or words.

DYSPHAGIA.

Difficulty in swallowing.

DYSPHONIA.

Disordered phonation or voice production.

DYSPLASIA.

The abnormal growth or development of a tissue or organ.

DYSTHYMIA.

A chronic mood disorder characterized by mild depression.

DYSTONIA.

Painful involuntary muscle cramps or spasms.

DYSTROPHIN.

A large protein that stabilizes the plasma membrane of a muscle cell during muscle contractions. Dystrophin is absent or reduced in the most common forms of muscular dystrophy.

E

ECHOCARDIOGRAM.

Ultrasound of the heart, which shows heart structure in detail.

ECHOLALIA.

Involuntary echoing of the last word, phrase, or sentence spoken by someone else.

EDEMA.

An accumulation of watery fluid that causes swelling of the affected tissue.

ELASTIN.

A protein that gives skin the ability to stretch and then return to normal.

ELBOW EXTENSION.

Movement away from the body at a jointed point.

ELECTROACUPUNCTURE.

A variation of acupuncture in which the practitioner stimulates the traditional acupuncture points electronically.

ELECTROCARDIOGRAM.

Test that shows a heart's rhythm by studying its electrical current patterns.

ELECTROENCEPHALOGRAM (EEG).

A record of the tiny electrical impulses produced by the brain's activity picked up by electrodes placed on the scalp. By measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain.

ELECTROLYTES.

Salts and minerals that produce electrically charged particles (ions) in body fluids. Common human electrolytes are sodium chloride, potassium, calcium, and sodium bicarbonate. Electrolytes control the fluid balance of the body and are important in muscle contraction, energy generation, and almost all major biochemical reactions in the body.

ELECTROMYOGRAPHY (EMG).

A diagnostic test that records the electrical activity of muscles. Small electrodes are placed on or in the skin and the patterns of electrical activity are projected on a screen or over a loudspeaker. This procedure is used to test for muscle disorders, including muscular dystrophy.

ELECTRON.

One of the small particles that make up an atom. An electron has the same mass and amount of charge as a positron, but the electron has a negative charge.

ELISA PROTOCOLS.

ELISA is an acronym for "enzyme-linked immunosorbent assay"; it is a highly sensitive technique for detecting and measuring antigens or antibodies in a solution.

EMBOLISM.

A blood clot, air bubble, or clot of foreign material that travels and blocks the flow of blood in an artery. When blood supply blocks a tissue or organ with an embolism, infarction (death of the tissue the artery feeds) occurs. Without immediate and appropriate treatment, an embolism can be fatal.

EMBOLIZATION.

A technique to stop or prevent hemorrhage by introducing a foreign mass, such as an air-filled membrane (balloon), into a blood vessel to block the flow of blood. This term also refers to an alternative to splenectomy that involves injecting silicone or a similar substances into the splenic artery to shrink the size of the spleen.

EMBOLUS.

A fragment of plaque or thrombus that breaks off from its original location and travels downstream to progressively narrower arteries, where it may block the vessel.

EMPHYSEMA.

An irreversible lung disease in which breathing becomes increasingly difficult.

ENCEPHALITIS.

Inflammation of the brain, usually caused by a virus. The inflammation may interfere with normal brain function and may cause seizures, sleepiness, confusion, personality changes, weakness in one or more parts of the body, and even coma.

ENCEPHALOGRAM.

Machine that detects brain activity by measuring its electrical impulses.

ENCEPHALOPATHIC.

Widespread brain disease or dysfunction.

ENCEPHALOPATHY.

Any abnormality in the structure or function of brain tissues.

ENDODONTIST.

A dentist who specializes in the treatment of diseases and injuries that affect the tooth root, dental pulp, and the tissues surrounding the tooth root.

ENDOLYMPH.

The fluid contained inside the membranous labyrinth of the inner ear.

ENDOLYMPHATIC HYDROPS.

Another term for Ménière's disease. It defines the disorder in terms of increased fluid pressure in the inner ear.

ENDOLYMPHATIC SAC TUMOR.

Growths that develop within inner ear structures called endolymph sacs.

ENDORPHINS.

A group of chemicals resembling opiates that are released in the body in response to trauma or stress. Endorphins react with opiate receptors in the brain to reduce pain sensations.

ENDOSCOPY.

A clinical technique using an instrument called an endoscope, used for visualization of structures within the body.

ENDOTHELIUM.

A layer of cells called endothelial cells that lines the inside surfaces of body cavities, blood vessels, and lymph vessels.

ENKEPHALINS.

Polypeptides that serve as neurotransmitters and short-acting pain relievers. Enkephalins also influence a person's perception of painful sensations.

ENTRAPMENT NEUROPATHY.

A disorder of the peripheral nervous system in which a nerve is damaged by compression as it passes through a bony or fibrous passage or canal. Many repetitive motion disorders are associated with entrapment neuropathies.

ENZYME.

A protein that catalyzes a biochemical reaction or change without changing its own structure or function.

EPIDIDYMIS.

Male genital structure usually connected to the testis; an area where sperm collect.

EPIDURAL HEMATOMA.

Bleeding into the area between the skull and the dura, the tough, outermost brain covering.

EPIDURAL SPACE.

The space immediately surrounding the outermost membrane (dura mater) of the spinal cord.

EPILEPSY.

A neurological disorder characterized by recurrent seizures with or without a loss of consciousness.

EQUINUS.

Excess contraction of the calf, causing toe walking.

ERB POINT.

A point 2-3 centimeters above the clavicle.

ERGONOMICS.

The branch of science that deals with human work and the efficient use of energy, including anatomical, physiological, biomechanical, and psychosocial factors.

ERGOT.

A compound produced by a fungus that grows on rye plants. It is used in the production of some abortive antimigraine drugs.

ERYTHEMA.

Redness of the skin due to congestion of the capillaries, usually due to injury, infection, or inflammation.

ERYTHROCYTE SEDIMENTATION RATE.

A test that measures the rate at which red blood cells settle out in a tube of anticoagulated blood, expressed in millimeters per hour; elevated sedimentation rates indicate the presence of inflammation.

ESOPHAGUS.

The tube leading from the back of the mouth, down the throat, and into the stomach.

ESSENTIAL TREMOR.

An uncontrollable (involuntary) shaking of the hands, head, and face. Also called familial tremor because it is sometimes inherited, it can begin in the teens or in middle age. The exact cause is not known.

ETIOLOGY.

The cause or origin of disease.

EUDYNIA.

The medical term for acute pain, or pain that is a symptom of an underlying disease or disorder.

EUPHORIA.

An exaggerated state of psychological and physical well being.

EUTHYROID.

State of normal function of the thyroid gland.

EXCISIONAL BIOPSY.

Removal of an entire lesion for microscopic examination.

EXCLUSION CRITERIA.

A predetermined set of factors that make a potential participant not eligible for inclusion in a clinical trial or study.

EXECUTIVE FUNCTIONS.

A set of cognitive abilities that control and regulate other abilities and behaviors. Necessary for goal-directed behavior, they include the ability to initiate and stop actions, to monitor and change behavior as needed, and to plan future behavior when faced with novel tasks and situations.

EXTENSIVE SUPPORT.

Ongoing daily support required to assist an individual in a specific adaptive area, such as daily help with preparing meals.

EXTRAPYRAMIDAL SYSTEM.

A functional rather than anatomical unit, it is comprised of nuclei and nerve fibers that are chiefly involved with subconscious, automatic aspects of motor coordination, but which also assist in the regulation of postural and locomotor movements.

F

FACIAL NERVE.

A cranial nerve that controls the muscles in the face.

FAILURE TO THRIVE.

Significantly reduced or delayed physical growth.

FASCICULATIONS.

Small involuntary muscle contractions visible under the skin.

FAST FOURIER TRANSFER.

A digital processing of the recorded signal resulting in a decomposition of its frequency components.

FATAL FAMILIAL INSOMNIA.

A rare, progressive neurological disease that is believed to be transmitted via an abnormal protein called a prion.

FEBRILE CONVULSION.

Seizures occurring mainly in children between three months and five years of age that are triggered by fever.

FEMORAL ARTERY.

An artery located in the groin area that is the most frequently accessed site for arterial puncture in angiography.

FETAL.

Refers to the fetus. In humans, the fetal period extends from the end of the eighth week of pregnancy to birth.

FETAL TISSUE TRANSPLANTATION.

A method of treating Parkinson's and other neurological diseases by grafting brain cells from human fetuses onto the affected area of the human brain. Human adults cannot grow new brain cells but developing fetuses can. Grafting fetal tissue stimulates the growth of new brain cells in affected adult brains.

FIBROMYALGIA.

A condition characterized by aching and stiffness, fatigue, and sleep disturbance, as well as pain at various sites on the body.

FILUM TERMINALE.

The strand of elastic, fibrous tissue that secures the lower end of the spinal cord.

FINGER AGNOSIA.

Inability to identify a particular finger.

FLACCID PARALYSIS.

Loss of muscle tone resulting from injury or disease of the nerves that innervate the muscles.

FLAIL.

To swing freely.

FLASHBACK.

A vivid sensory or emotional experience that happens independently of the initial event or experience. Flashbacks resulting from the use of LSD are sometimes referred to as hallucinogen persisting perception disorder, or HPPD.

FLUORESCEIN DYE.

An orange dye used to illuminate the blood vessels of the retina in fluorescein angiography.

FLUOROSCOPE.

An imaging device that displays x rays of the body. Fluoroscopy allows the radiologist to visualize the guide wire and catheter moving through the patient's artery.

FOCAL.

Limited to a defined area.

FORAMEN MAGNUM.

Large opening in the back of the skull, where the spinal cord connects with the brain.

FORAMINOTOMY.

Surgery to enlarge the bony hole, or foramen, where a nerve root enters or exits the spinal canal.

FRAGILE X SYNDROME.

A genetic condition related to the X chromosome that affects mental, physical, and sensory development. It is the most common form of inherited mental retardation.

FREE RADICAL.

An unstable molecule that causes oxidative damage by stealing electrons from surrounding molecules, thereby disrupting activity in the body's cells.

FRONTAL CORTEX.

The part of the human brain associated with aggressiveness and impulse control. Abnormalities in the frontal cortex are associated with an increased risk of suicide.

FRONTAL LOBE.

The area of the brain responsible for higher thinking.

G

GAIT.

The way in which one walks.

GAMMA RAY.

A high-energy photon emitted by radioactive substances.

GANGLION.

A mass of nerve cells usually found outside the central nervous system, from which axons arrive from the periphery and proceed to the spinal cord or brain; plural form: ganglia.

GANGLIOSIDE.

A fatty (lipid) substance found within the brain and nerve cells.

GANGRENE.

The death of tissue caused by loss of blood supply. Gangrene is a serious potential side effect of taking ergot alkaloids.

GASTROPARESIS.

Nerve damage of the stomach that delays or stops stomach emptying, resulting in nausea, vomiting, bloating, discomfort, and weight loss.

GELASTIC SEIZURES.

Seizures manifesting with brief involuntary laughter

GENE.

A building block of inheritance, it contains the instructions for the production of a particular protein and is made up of a molecular sequence found on a section of DNA. Each gene is found at a precise location on a chromosome.

GENERALIZED ANXIETY DISORDER.

An anxiety disorder characterized by excessive worry or fear about a number of activities or events.

GENOME.

The entire collection of genes of an individual.

GENOTYPE.

The genetic makeup of an organism or a set of organisms.

GINGIVAL FIBROMA.

Small non-cancerous growth on the toe or finger nail beds.

GLASGOW COMA SCALE.

A measure of level of consciousness and neurological functioning after traumatic brain injury (TBI).

GLAUCOMA.

A common eye disease characterized by increased fluid pressure in the eye that damages the optic nerve, which carries visual impulses to the brain. Glaucoma can be caused by another eye disorder, such as a tumor or congenital malformation, or it can appear without obvious cause. If untreated it generally leads to blindness.

GLIAL CELL.

Nerve tissue of the central nervous system other than the signal-transmitting neurons. Glial cells are interspersed between neurons, providing support and insulation.

GLIOMA.

A tumor that originates in the cells supporting and nourishing brain neural tissue (glial cells).

GLOBOID CELLS.

Large cells containing excess toxic metabolic "waste" of galactosylceramide and psychosine.

GLUCOCORTICOID MEDICATIONS.

A group of medications that produces effects of the body's own cortisone and cortisol. Glucocorticoids are commonly called steroids and, among other functions, work to reduce inflammation,

GLUCOSYLCERAMIDE.

A chemical substance composed of glucose (sugar) and lipid (fat).

GLYCOGEN.

The principle form of carbohydrate energy (glucose) stored within the muscles and liver.

GOITER.

A swelling or enlargement of the thyroid gland.

GRAY MATTER.

Areas of the brain and spinal cord that are comprised mostly of unmyelinated nerves.

GUIDE WIRE.

A wire that is inserted into an artery to guide a catheter to a certain location in the body.

GUSTATORY.

Pertaining to the sense of taste.

H

HALLUCINATION.

A false or distorted perception of objects, sounds, or events that seems real. Hallucinations usually result from drugs or mental disorders.

HALLUCINOGEN.

A drug or other substance that induces hallucinations.

HAMARTOMA.

Abnormal growth that may resemble cancer, but is not cancerous.

HANDEDNESS.

The preference of either the right or left hand as the dominant hand for the performance of tasks such as writing.

HAPTIC.

Pertaining to the sense of touch.

HEMANGIOBLASTOMA.

Tumor often found in the brain, as in von Hippel-Lindau disease.

HEMATOMA.

A localized collection of blood, often clotted, in body tissue or an organ, usually due to a break or tear in the wall of blood vessel.

HEMICHOREA.

Chorea that affects only one side of the body.

HEMIPARESIS.

Muscle weakness of one side of the body.

HEMIPLEGIA.

Paralysis on one side of the body.

HEMIPLEGIC MIGRAINE.

Migraine accompanied by temporary paralysis on one side of the body.

HEMISPHERE.

One side of the brain, right or left.

HEMOPHILIAC.

A person with the blood disorder hemophilia, an inherited deficiency in blood-clotting ability. Hemophiliacs require regular administration of blood products, and were especially at risk of acquiring AIDS from HIV-contaminated blood during the early years of the evolving AIDS epidemic, before tests were developed to identify the HIV virus in donated blood.

HEMORRHAGE.

Severe, massive bleeding that is difficult to control. The bleeding may be internal or external.

HEPATIC ENCEPHALOPATHY.

A change in mental state due to toxic substance buildup in the blood that is caused by liver failure.

HEPATITIS.

An inflammation of the liver, with accompanying liver cell damage or cell death, caused most frequently by viral infection, but also by certain drugs, chemicals, or poisons. May be either acute (of limited duration) or chronic (continuing). Symptoms include jaundice, nausea, vomiting, loss of appetite, tenderness in the right upper abdomen, aching muscles, and joint pain. In severe cases, liver failure may result.

HEPATOSPLENOMEGALY.

Enlargement of the liver and spleen.

HEPATOTOXICITY.

Damaging or destructive to the liver.

HEREDITARY ATAXIA.

One of a group of hereditary degenerative diseases of the spinal cord or cerebellum. These diseases cause tremor, spasm, and wasting of muscle.

HERNIATED DISC.

A blisterlike bulging or protrusion of the contents of the disk out through the fibers that normally hold them in place. It is also called a ruptured disk, slipped disk, or displaced disk.

HERPES.

A virus that causes cold sores, sexually transmitted diseases, shingles, or chicken pox.

HERPES SIMPLEX VIRUS.

A virus that can cause fever and blistering on the skin and mucous membranes. Herpes simplex 1 infections usually occur on the face (cold sores) and herpes simplex 2 infections usually occur in the genital region.

HERPES VARICELLA ZOSTER VIRUS.

The virus that typically causes chicken pox in children; then may reactivate later in life to cause shingles.

HIB DISEASE.

An infection caused by Haemophilus influenza, type b (Hib). This disease mainly affects children under the age of five. In that age group, it is the leading cause of bacterial meningitis, pneumonia, joint and bone infections, and throat inflammations.

HIPPOCAMPUS.

A part of the brain that is involved in memory formation and learning. The hippocampus is shaped like a curved ridge and belongs to an organ system called the limbic system.

HISTAMINE.

A substance released by immune system cells in response to the presence of an allergen. It stimulates widening of blood vessels and increased porousness of blood vessel walls so that fluid and protein leak out from the blood into the surrounding tissue, causing localised inflammation of the tissue.

HISTOLOGIC.

Pertaining to histology, the study of cells and tissues at the microscopic level.

HISTOLOGY.

The study of tissue structure.

HOLOPROSENCEPHALY.

Brain, cranial, and facial malformations present at birth that are caused by incomplete cleavage of the brain during embryologic development.

HOMEOSTASIS.

The balanced internal environment of the body and the automatic tendency of the body to maintain this internal "steady state." Also refers to the tendency of a family system to maintain internal stability and to resist change.

HORMONE.

Chemical substance produced by certain endocrine glands that is released into the bloodstream where it controls and regulates functioning of several other tissues.

HUMAN IMMUNODEFICIENCY VIRUS (HIV).

A transmissible retrovirus that causes AIDS in humans. Two forms of HIV are now recognized: HIV-1, which causes most cases of AIDS in Europe, North and South America, and most parts of Africa; and HIV-2, which is chiefly found in West African patients. HIV-2, discovered in 1986, appears to be less virulent than HIV-1 and may also have a longer latency period.

HYDROCEPHALUS.

An abnormal accumulation of cerebrospinal fluid within the brain. This accumulation can be harmful by pressing on brain structures and thereby damaging them.

HYPERCAPNIA.

Excess carbon dioxide in the blood.

HYPEREMESIS GRAVIDARUM.

Uncontrollable nausea and vomiting associated with pregnancy. Acupuncture appears to be an effective treatment for women with this condition.

HYPEREXTENSION.

Extension of a limb or body part beyond the normal limit.

HYPERFUNCTION.

Term used to describe excess effort or strain involved in producing an action.

HYPERHIDROSIS.

Excessive sweating. Hyperhidrosis can be caused by heat, overactive thyroid glands, strong emotion, menopause, or infection.

HYPERLIPIDEMIA.

A condition characterized by abnormally high levels of lipids in blood plasma.

HYPERPIGMENTATION.

An excess of melanin, leading to abnormal areas of increased dark skin color.

HYPERREFLEXIA.

An increased reaction to reflexes.

HYPERTENSION.

Abnormally high arterial blood pressure, which if left untreated can lead to heart disease and stroke.

HYPERTHERMIA.

Elevated body temperature.

HYPERTHYROID.

State of excess thyroid hormone in the body.

HYPERTHYROIDISM.

Abnormally high levels of thyroid hormone. About 2% of patients with this condition develop chorea.

HYPERTONUS.

Increased tension of a muscle or muscle spasm.

HYPERVENTILATION.

A pattern of rapid but shallow breathing that is frequently found in patients with Rett syndrome.

HYPNOGOGIC.

Pertaining to drowsiness. It is usually used to describe hallucinations that occur as a person falls asleep.

HYPNOGOGIC HALLUCINATION.

A vivid, dream-like hallucination, such as the sensation of falling, that occurs at the onset of sleep.

HYPNOPOMPIC.

Persisting after sleep. It is usually used to describe hallucinations that occur as a person awakens.

HYPNOTICS.

A class of drugs that are used as sedatives and sleep aids.

HYPOCALCEMIA.

A condition characterized by an abnormally low level of calcium in the blood.

HYPOMELANOTIC MACULE.

Skin patch that is lighter in color than the area around it.

HYPOPIGMENTATION.

A deficiency of melanin, leading to abnormal areas of lighter skin color.

HYPOPITUITARISM.

A condition characterized by underactivity of the pituitary gland.

HYPOTHALAMUS.

The lowermost part of the diencephalon, containing several nuclei, nerve tracts, and the pituitary gland; it is the regulatory seat of the autonomic nervous system, controlling heartbeat, body temperature, thirst, hunger, blood pressure, blood sugar levels, and other functions.

HYPOTHYROIDISM.

A disorder in which the thyroid gland produces too little thyroid hormone causing a decrease in the rate of metabolism with associated effects on the reproductive system. Symptoms include fatigue, difficulty swallowing, mood swings, hoarse voice, sensitivity to cold, forgetfulness, and dry/coarse skin and hair.

HYPOTONIA.

Having reduced or diminished muscle tone or strength.

HYPOTONUS.

Decreased tension of a muscle, or abnormally low muscle tone.

HYPOXEMIA.

Abnormally low blood oxygen.

HYPOXIA.

A condition characterized by insufficient oxygen in the cells of the body

HYPOXIC.

Oxygen deficient.

HYPSARRHYTHMIA.

Typical brain wave activity found in infantile spasms.

I

ICHTHYOSIS.

Dry, thickened, rough, coarse skin, sometimes with evident scaling.

ICTAL EEG.

An electroencephalogram (EEG) done to determine the type of seizure characteristic of a person's disorder. During this EEG, seizure medicine may be discontinued in an attempt to induce as seizure during the testing period.

IDIOPATHIC.

Of unknown cause or spontaneous origin. Ménière's disease and some headaches are considered idiopathic disorders.

ILLUSION.

A false visual perception of an object that others perceive correctly. A common example is the number of sightings of UFOs that turn out to be airplanes or weather balloons.

IMMUNOADSORPTION.

A procedure that can remove harmful antibodies from the blood.

IMMUNOCOMPROMISED.

A state in which the immune system is suppressed or not functioning properly.

IMMUNOGLOBULIN.

A protein molecule formed by mature B-cells in response to foreign proteins in the body; the building blocks for antibodies.

IMMUNOHISTOCHEMISTRY.

A method of detecting the presence of specific proteins in cells or tissues.

IMMUNOSUPPRESSANTS.

Drugs that reduce or eliminate the body's ability to make an immune response.

INBORN ERROR OF METABOLISM.

One of a group of rare conditions characterized by an inherited defect in an enzyme or other protein. Inborn errors of metabolism can cause brain damage and mental retardation if left untreated. Phenylketonuria, Tay-Sachs disease, and galactosemia are inborn errors of metabolism.

INCISIONAL BIOPSY.

Removal of a small part of a sample tissue area for microscopic examination.

INCLUSION BODY.

A small intracellular body found within the cytoplasm or nucleus of another cell, characteristic of disease.

INCLUSION CRITERIA.

A predetermined set of factors that make a potential participant eligible for inclusion in a clinical trial or study.

INCONTINENCE.

Inability to control excretory functions such as defecation and urination.

INCOORDINATION.

Loss of voluntary muscle control resulting in irregular movements.

INCREASED INTRACRANIAL PRESSURE.

Increased overall pressure inside the skull.

INFARCT.

An area of dead tissue caused by inadequate blood supply; in the brain, this condition is called a stroke.

INFLAMMATION.

The body's response to injury, resulting in swelling, warmth, redness, pain.

INGUINAL.

Referring to the groin area.

INNERVATION.

Distribution or supply of nerves to a structure.

INSIDIOUS.

Developing in a stealthy or gradual manner.

INSULIN.

A hormone or chemical produced by the pancreas that is needed by cells of the body in order to use glucose (sugar), a major source of energy for the human body.

INTENTION TREMOR.

A rhythmic purposeless shaking of the muscles that begins with purposeful (voluntary) movement. This tremor does not affect muscles that are resting.

INTERFERON ALFA.

A potent immune-defense protein that is used as an anti-cancer drug.

INTERLEUKINS.

Chemicals released in the body as a result of stress.

INTERMEDIATE CARE FACILITY.

An inpatient facility that provides periodic nursing care.

INTERVERTEBRAL DISCS.

Gelatinous structures separating the spinal vertebrae and acting as shock absorbers.

INTRACEREBRAL HEMATOMA.

Bleeding within the brain caused by trauma to a blood vessel.

INTRACEREBRAL HEMORRHAGE.

A cause of some strokes in which vessels within the brain begin bleeding.

INTRACRANIAL HYPERTENSION.

Increase in pressure in the brain.

INTRACRANIAL PRESSURE.

The overall pressure within the skull.

INTRAOCULAR.

Inside the eye.

INTRAVENTRICULAR HEMORRHAGE.

Bleeding into the brain, specifically into the ventricles.

IONIZING RADIATION.

High-energy radiation such as that produced by x rays.

IRIS.

The circular membrane that forms the colored portion of the eye and expands or contracts around the pupil.

IRITIS.

Inflammation of the iris, the membrane in the pupil, the colored portion of the eye. It is characterized by photophobia, pain, and inflammatory congestion.

IRRITATIVE HALLUCINATIONS.

Hallucinations caused by abnormal electrical activity in the brain.

ISCHEMIA.

A decrease in the blood supply to an area of the body caused by obstruction or constriction of blood vessels.

J

JAUNDICE.

Yellowing of the skin or eyes due to excess of bilirubin in the blood.

K

KARYOTYPE.

A standard arrangement of photographic or computer-generated images of chromosome pairs from a cell in ascending numerical order, from largest to smallest.

KETOACIDOSIS.

Usually caused by uncontrolled type I diabetes, when the body isn't able to use glucose for energy. As an alternate source of energy, fat cells are broken down, producing ketones, toxic compounds that make the blood acidic. Symptoms of ketoacidosis include excessive thirst and urination, abdominal pain, vomiting, rapid breathing, extreme tiredness, and drowsiness.

KI.

The Japanese spelling of qi, the traditional Chinese term for vital energy or the life force.

KINETIC.

Word taken from the Greek (kinesis): motion.

KYPHOSIS.

An abnormal convex (outward) curvature of the upper portion of the spinal column, sometimes called a humpback or hunchback.

L

LABYRINTH.

The inner ear. It consists of the membranous labyrinth, which is a system of sacs and ducts made of soft tissue; and the osseous or bony labyrinth, which surrounds and contains the membranous labyrinth.

LABYRINTHECTOMY.

Surgical removal of the labyrinth of the ear. It is done to treat Ménière's disease only when the patient has already suffered severe hearing loss.

LACINATING PAIN.

Piercing, stabbing, or darting pain.

LAMINA.

Flat plates of bone that form part of a vertebrae.

LARYNGEAL STRIDOR.

Constriction of the voice box, causing vocal hoarseness.

LARYNX.

The "voice box," located between the pharynx (upper area of the throat) and the trachea (windpipe).

LATERAL FLEXION.

To flex toward a side.

LATERAL GENICULATE NUCLEI.

A structure that receives and processes impulses from the optic nerve; it sends these impulses farther into the brain for more processing.

LEFT VENTRICULAR ENLARGEMENT.

Abnormal enlargement of the left lower chamber of the heart.

LEPTOMENINGEAL ANGIOMA.

A swelling of the tissue or membrane surrounding the brain and spinal cord, which can enlarge with time.

LESION.

A disruption of the normal structure and function of a tissue by an injury or disease process. Wounds, sores, rashes, and boils are all lesions.

LEUKEMIA.

A cancer of the blood-forming organs (bone marrow and lymph system) characterized by an abnormal increase in the number of white blood cells in the tissues. There are many types of leukemias and they are classified according to the type of white blood cell involved.

LEUKOCYTOSIS.

An elevated white blood cell count.

LEUKODYSTROPHY.

A disease that affects the white matter called myelin in the central nervous system (CNS).

LEUKOMALACIA.

Softening of the brain's white matter.

LEVODOPA.

A substance used in the treatment of Parkinson's disease. Levodopa can cross the blood-brain barrier that protects the brain. Once in the brain, it is converted to dopamine and thus can replace the dopamine lost in Parkinson's disease.

LEWY BODIES.

Spheres, found in the bodies of dying cells, that are considered to be a marker for Parkinson's disease.

LIGAMENT.

A type of tough, fibrous tissue that connects bones or cartilage and provides support and strength to joints.

LIMBIC SYSTEM.

A group of structures in the brain that includes the hypothalamus, amygdala, olfactory bulbs, and hippocampus. The limbic system plays an important part in the regulation of human moods and emotions. Many psychiatric disorders are related to malfunctioning of the limbic system.

LIMITED SUPPORT.

A predetermined period of assistance required to deal with a specific event, such as training for a new job.

LIPIDS.

Organic compounds not soluble in water but soluble in fat solvents such as alcohol. Lipids are stored in the body as energy reserves and are important components of cell membranes. Commonly known as fats.

LIPOPIGMENTS.

Substances made up of fats and proteins found in the body's tissues.

LIPOPROTEINS.

Compounds of protein that carry fats and fat-like substances such as cholesterol in the blood.

LISCH NODULE.

A benign growth within the iris of the eye.

LIVER ENCEPHALOPATHY.

A condition in which the brain is affected by a buildup of toxic substances that would normally be removed by the liver. The condition occurs when the liver is too severely damaged to cleanse the blood effectively.

LOCOMOTOR.

Means of or pertaining to movement or locomotion.

LORDOSIS.

Anterior curvature of the spine, creating a swayback appearance.

LUMBAR.

Referring to the lower back. There are five lumbar vertebrae.

LUMBAR PUNCTURE.

A diagnostic procedure in which a needle is inserted into the lower spine to withdraw a small amount of cerebrospinal fluid.

LYME BORRELIOSIS.

Another name for Lyme disease.

LYMPHADENOPATHY.

Swelling of the lymph glands.

LYMPHANGIOLEIMYOMA.

Non-cancerous growth in the lung, typical of tuberous sclerosis.

LYMPHOCYTE.

A type of white blood cell that participates in the immune response. The two main groups are the B-cells that have antibody molecules on their surface and T-cells that destroy antigens.

LYMPHOCYTIC MENINGITIS.

Benign infection of brain coverings that protect the brain

LYMPHOMA.

A malignant tumor of the lymph nodes.

LYSOSOME.

Membrane-enclosed compartment in cells, containing many hydrolytic enzymes; where large molecules and cellular components are broken down.

M

MACROPHAGE.

A large, versatile immune cell that acts as a scavenger, engulfing dead cells, foreign substances, and other debris.

MACULE.

A small, flat area of abnormal color on the skin.

MAGNETIC RESONANCE IMAGING (MRI).

An imaging technique used in evaluation and diagnoses of the brain and other parts of the body.

MAJOR DEPRESSIVE DISORDER.

A mood disorder characterized by overwhelming and persistent feelings of hopelessness, often accompanied by sleep disturbances, withdrawal from normal social and personal care activities, and an inability to concentrate.

MALABSORPTION.

The inability to adequately or efficiently absorb nutrients from the intestinal tract.

MALDYNIA.

The medical term for chronic pain, or pain that has become a disease in and of itself as a result of changes in the patient's nervous system.

MALINGERING.

Knowingly pretending to be physically or mentally ill in order to get out of some unpleasant duty or responsibility, or for economic benefit.

MANIC.

A period of excess mental activity, often accompanied by elevated mood and disorganized behavior.

MASTOID BONE.

The bony areas behind and below the ears. Also called the mastoid process.

MEDIAN NERVE.

A nerve that runs through the wrist and into the hand. It provides sensation and some movement to the hand, the thumb, the index finger, the middle finger, and half of the ring finger.

MEDICAID.

A program jointly funded by state and federal governments that reimburses hospitals and physicians for the care of individuals who cannot pay for their own medical expenses. These individuals may be in low-income households or may have chronic disabilities.

MEDULLA.

The lowermost portion of the brain stem (it borders the spinal cord) that controls vital functions like respiration, blood pressure, swallowing, and heart rate. Also called the medulla oblongata.

MENINGES.

The three-layered membranous covering of the brain and spinal cord.

MENINGIOMA.

A tumor made up of cells of the lining of the brain and spinal cord (meninges).

MENINGITIS.

An infection or inflammation of the membranes that cover the brain and spinal cord (the meninges). It is usually caused by bacteria or a virus.

MERIDIANS.

In traditional Chinese medicine, the channels that run beneath the skin through which the body's energy, chi (sometimes spelled "qi" or "ki") flows.

METABOLIC.

Refers to the chemical reactions in living organisms.

METABOLIC ACIDOSIS.

Overly acidic condition of the blood.

METABOLISM.

The group of biochemical processes within the body that release energy in support of life.

METANEPHRINE.

A byproduct of epinephrine, found elevated in urine if a pheochromocytoma is present.

METASTASIS.

The spread of cancer from one part of the body to another. Cells in the metastatic (secondary) tumor are like those in the original (primary) tumor.

MICROCEPHALY.

An abnormally small head and underdeveloped brain.

MICROTUBULES.

Slender, elongated, anatomical channels.

MIGRAINE.

Recurrent severe headaches generally accompanied by an aura (classic migraine), nausea, vomiting, and dizziness.

MILLIGRAM.

One thousandth of a gram; the metric measure that equals 0.035 ounces.

MINERALOCORTICOID.

A steroid hormone, like aldosterone, that regulates the excretion of salt, potassium, and water.

MITOCHONDRIA.

Spherical or rod-shaped structures of the cell. Mitochondria contain genetic material (DNA and RNA) and are responsible for converting food to energy.

MITOCHONDRIAL DNA.

The genetic material found in mitochondria, the organelles that generate energy for the cell. Because reproduction is by cloning, mitochondrial DNA is usually passed along female lines.

MITRAL VALVE PROLAPSE.

A heart defect in which one of the valves of the heart (which normally controls blood flow) becomes floppy. Mitral valve prolapse may be detected as a heart murmur, but there are usually no symptoms.

MONOAMINE OXIDASE INHIBITORS.

A class of antidepressants used to treat certain types of mental depression. MAO inhibitors are especially useful in treating people whose depression is combined with other problems such as anxiety, panic attacks, phobias, or the desire to sleep too much.

MONONEUROPATHY.

Disorder involving a single nerve.

MONOZYGOTIC TWINS.

Twins that are genetically identical and are always of the same gender.

MOTOR.

Of or pertaining to motion, the body structures involved in movement, or the brain functions that direct such deliberate movement.

MOTOR FUNCTION.

The ability to produce body movement by complex interaction of the brain, nerves and muscles.

MOTOR NERVES.

Motor or efferent nerve cells, they carry impulses from the brain to muscle or organ tissue.

MOTOR NEURON.

A nerve cell that specifically controls and stimulates voluntary muscles.

MOTOR NEURON DISEASE.

A neuromuscular disease, usually progressive, that causes degeneration of motor neuron cells and loss or diminishment of voluntary muscle control.

MOTOR UNIT ACTION POTENTIALS.

Spikes of electrical activity recorded during an electromyogram (EMG) that reflect the number of motor units (motor neurons and the muscle fibers they transmit signals to) activated when the patient voluntarily contracts a muscle.

MOVEMENT EDUCATION.

A term that refers to the active phase of bodywork, in which clients learn to move with greater freedom and to maintain the proper alignment of their bodies.

MOXIBUSTION.

A technique in traditional Chinese medicine that involves burning a "Moxa," or cone of dried wormwood leaves, close to the skin to relieve pain. When used with acupuncture, the cone is placed on top of the needle at an acupuncture point and burned

MUCOPOLYSACCHARIDE.

A complex molecule made of smaller sugar molecules strung together to form a chain. It is found in mucous secretions and intercellular spaces.

MULTIPLE MONONEUROPATHY.

Neuropathy affecting several individual nerve trunks.

MULTIPLE SCLEROSIS.

A progressive, autoimmune disease of the central nervous system characterized by damage to the myelin sheath that covers nerves. The disease, which causes progressive paralysis, is marked by periods of exacerbation and remission.

MUSCLE TONE.

Also termed tonus; the normal state of balanced tension in the tissues of the body, especially the muscles.

MUTATION.

A permanent change in the genetic material that may alter a trait or characteristic of an individual, or manifest as disease. It can be transmitted to offspring.

MYASTHENIA.

Muscular weakness or a group of chronic muscular diseases characterized by muscle weakness.

MYASTHENIA GRAVIS.

A chronic, autoimmune, neuromuscular disease with symptoms that include muscle weakness and sometimes paralysis.

MYELIN.

A fatty sheath surrounding nerves throughout the body that helps them conduct impulses more quickly.

MYELOGRAM.

An x-ray exam of the spinal cord, nerves, and other tissues within the spinal cord that are highlighted by injected contrast dye.

MYELOGRAPHY.

A test in which dye is injected into the spinal canal and the patient is then tilted in different directions on a special table, allowing dye to outline the spinal cord and nerve roots and to show areas of compression.

MYELOMENINGOCELE.

A sac that protrudes through an abnormal opening in the spinal column.

MYELOPATHY.

A disorder in which the tissue of the spinal cord is diseased or damaged.

MYOCARDIAL INFARCTION.

Commonly known as a heart attack, a myocardial infarction is an episode in which some of the heart's blood supply is severely cut off or restricted, causing the heart muscle to suffer and die from lack of oxygen.

MYOCLONUS.

Involuntary contractions of a muscle or an interrelated group of muscles. Also known as myoclonic seizures.

MYOFILAMENT.

Ultrastructural microscopic unit of a muscle that is made up of proteins that contract.

MYOPATHY.

Any abnormal condition or disease of muscle tissue, characterized by muscle weakness and wasting.

MYOSITIS.

Inflammation of a muscle.

MYOTONIA.

The inability to normally relax a muscle after contracting or tightening it.

N

NARCOLEPSY.

A life-long sleep disorder marked by four symptoms: sudden brief sleep attacks, cataplexy (a sudden loss of muscle tone usually lasting up to 30 minutes), temporary paralysis, and hallucinations. The hallucinations are associated with falling asleep or the transition from sleeping to waking.

NARCOTIC.

Another term for opioid drugs that refers to their ability to produce drowsiness as well as relieve pain.

NASAL POLYPS.

Drop-shaped overgrowths of the nasal membranes.

NECROSIS.

Cellular or tissue death; skin necrosis may be caused by multiple, consecutive doses of radiation from fluoroscopic or x-ray procedures.

NEOPLASM.

An abnormal growth of tissue or cells (a tumor) that may be either malignant (cancerous) or benign.

NERVE.

Fibers that carry sensory information, movement stimuli, or both from the brain and spinal cord to other parts of the body and back again. Some nerves, including the vagus nerve, innervate distantly separated parts of the body.

NERVE CONDUCTION.

The speed and strength of a signal being transmitted by nerve cells. Testing these factors can reveal the nature of nerve injury, such as damage to nerve cells or to the protective myelin sheath.

NERVE CONDUCTION STUDY.

Testing that shows electrical impulse activity along nerves.

NERVE CONDUCTION VELOCITY.

A recording of how well a nerve conducts electrical impulses.

NERVE IMPULSE.

The electrochemical signal carried by an axon from one neuron to another neuron.

NERVE ROOT.

Two groups of nerves that run from the spinal cord to join and form the spinal nerves.

NEURAL TUBE.

A hollow column of ectodermal tissue that forms in early embryonic development and goes on to become the spinal cord and spinal column.

NEURAL TUBE DEFECT.

A birth defect caused by abnormal closure or development of the neural tube, the embryonic structure that gives rise to the central nervous system.

NEURALGIA.

Pain along the pathway of a nerve.

NEUROBLASTOMA.

A malignant tumor of nerve cells that strikes children.

NEUROCUTANEOUS.

Conditions involving unique manifestations of the skin, hair, teeth, and nervous system, usually with familial tendencies.

NEURODEGENERATIVE.

Relating to the deterioration of nerve tissues.

NEURODEGENERATIVE DISEASE.

A disease in which the nervous system progressively and irreversibly deteriorates.

NEUROFIBRILLARY TANGLES.

Abnormal structures composed of twisted masses of protein fibers within nerve cells. They are found in the brains of persons with Alzheimer's disease.

NEUROFIBROMAS.

Soft, rubbery, flesh-colored tumors made up of the fibrous substance that covers peripheral nerves.

NEUROFIBROMATOSIS.

Also called von Reclinghausen's disease; a disease in which tumors grow on nerve cells throughout the body.

NEUROGENIC.

Caused by or originating in the nerves.

NEUROGENIC PAIN.

Pain originating in the nerves or nervous tissue and following the pathway of a nerve.

NEUROLEPTIC.

Another name for the older type of antipsychotic medications, such as haloperidol and chlorpromazine, prescribed to treat psychotic conditions.

NEUROMUSCULAR.

Involving both the muscles and the nerves that control them.

NEUROMUSCULAR DISEASE.

Disease involving both the muscles and the nerves that control them.

NEUROMUSCULAR JUNCTION.

The site at which nerve impulses are transmitted to muscles.

NEURON.

A cell specialized to conduct and generate electrical impulses and to carry information from one part of the brain to another.

NEURONAL CEROID LIPOFUSCINOSES.

A family of four progressive neurological disorders.

NEURONAL MIGRATION.

A step of early brain development in which nerve cells travel over large distances to different parts of the brain.

NEUROPATHIC BLADDER.

Improper or lack of bladder function, due to a nerve problem.

NEUROPATHY.

A disease or abnormality of the peripheral nerves (the nerves outside the brain and spinal cord). Major symptoms include weakness, numbness, paralysis, or pain in the affected area.

NEUROSYPHILIS.

This is the slowly progressive destruction of the brain and spinal cord due to untreated tertiary (late-stage) syphilis. It can be asymptomatic or cause different disorders like tabes dorsalis, general paresis, and meningovascular syphilis.

NEUROTOXIN.

A poison that acts directly on the central nervous system.

NEUROTRANSMISSION.

The process in which a neurotransmitter travels across the synapse to act on the target cell to either inhibit or excite it.

NEUROTRANSMITTER.

A chemical messenger that transmits an impulse from one nerve cell to the next.

NOCICEPTOR.

A specialized type of nerve cell that senses pain.

NOREPINEPHRINE.

A hormone that controls blood pressure and heart rate. It is also a chemical found in the brain that is thought to play a role in attention deficit hyperactivity disorder (ADHD).

NUCLEUS PULPOSUS.

Central core of a vertebrae.

NYSTAGMUS.

An involuntary, rhythmic movement of the eyes.

O

OBSESSION.

A persistent or recurrent thought, image, or impulse that is unwanted and distressing.

OBSTRUCTIVE SLEEP APNEA.

The most common form of sleep apnea characterized by repeated episodes of upper airway obstruction during sleep.

OCCIPITAL LOBE.

The back part of the brain that functions as a visual interpretation center.

OCCIPITAL NERVES.

Two pairs of nerves that originate in the area of the second and third vertebrae of the neck. They are part of a network that innervate the neck, upper back, and head.

OCCLUSION.

Blockage.

OLFACTORY.

Pertaining to the sense of smell.

OPHTHALMIC ARTERY.

The artery supplying the eye and adjacent structures with blood.

OPHTHALMOPARESIS.

Paralysis of one or more of the muscles of the eye.

OPHTHALMOPLEGIA.

Paralysis of the motor nerves of the eye, resulting in wandering or floating eye movements or drooping eyelids.

OPIOID.

Any natural or synthetic substance that produces the same effects as an opiate, such as pain relief, sedation, constipation, and respiratory depression. Some opioids are produced by the human body (e.g., endorphins), while others are produced in the laboratory (e.g., methadone).

OPPORTUNISTIC INFECTION.

An infection in a person with an impaired immune system caused by an organism that does not usually cause disease in people with healthy immune systems.

OPSOCLONUS.

Often called "dancing eyes," this symptom involves involuntary, quick darting movements of the eyes in all directions.

OPTIC NERVE.

The bundle of nerve fibers that carry visual messages from the retina to the brain.

OPTIC NEURITIS.

Inflammation of the optic nerve, often accompanied by vision loss.

OREXIN.

Another name for hypocretin, a chemical secreted in the hypothalmus that regulates the sleep/wake cycle. Narcolepsy is sometimes described as an orexin deficiency syndrome.

ORGANELLE.

A specialized structure within a cell, which is separated from the rest of the cell by a membrane composed of lipids and proteins, where chemical and metabolic functions take place.

ORGANIC BRAIN SYNDROME.

A brain disorder that is caused by defective structure or abnormal functioning of the brain.

ORTHOSTATIC HYPOTENSION.

A drop in blood pressure that causes faintness or dizziness and occurs when an individual rises to a standing position. Also known as postural hypotension.

ORTHOTIC DEVICE.

An external device, such as a splint or a brace, that prevents or assists movement. Also called an orthosis.

OSSICLES.

Tiny bones in the middle ear—the incus, malleus, and stapes—that convey sound impulses from the eardrum to the inner ear.

OSTEOPOROSIS.

Literally meaning "porous bones," this condition occurs when bones lose an excessive amount of their protein and mineral content, particularly calcium. Over time, bone mass and strength are reduced leading to increased risk of fractures.

OTITIS MEDIA.

Inflammation, usually with infection, of the middle ear.

OTOLARYNGOLOGIST.

A physician who specializes in medical and surgical treatment of disorders of the ear, nose, throat, and larynx.

OTOLARYNGOLOGY.

The branch of medicine that treats disorders of the ear, nose, and throat.

OTOLITH ORGANS.

Organs in the vestibular apparatus that sense horizontal and vertical movements of the head.

OTOLOGY.

The branch of medicine that specializes in medical or surgical treatment of ear disorders.

OTOSCLEROSIS.

Abnormal bone development in the middle ear, resulting in progressive hearing loss.

P

PAIN MEDICINE.

The medical specialty that deals with the study and prevention of pain, and with the evaluation, treatment, and rehabilitation of patients with acute or chronic pain.

PALLIDOTOMY.

A surgical procedure that destroys a small part of a tiny structure within the brain called the globus pallidus internus. This structure is part of the basal ganglia, a part of the brain involved in the control of willed (voluntary) movement of the muscles.

PALPITATION.

A heartbeat that is more pronounced, often felt physically.

PALSY.

Uncontrollable tremors.

PANDEMIC.

Widespread epidemic.

PANIC DISORDER.

An anxiety disorder in which people have sudden and intense attacks of fear in certain situations. Symptoms such as shortness of breath, sweating, dizziness, chest pain, and extreme fear often accompany the attacks.

PAPILLEDEMA.

Swelling of the optic disk inside the eye (the portion of the optic nerve that collects nerves from the light sensitive layer of the eye, the retina); often caused by increased pressure inside the head.

PARALYSIS.

Loss of the ability to move one or more parts of the body voluntarily due to muscle or nerve damage.

PARANEOPLASTIC SYNDROME.

A set of symptoms associated with cancer but not directly caused by the cancer.

PARAPARESIS.

Weakness of the legs.

PARAPLEGIA.

Loss of voluntary movement and sensation of both lower extremities.

PARASITE.

An organism that lives and feeds in or on another organism (the host) and does nothing to benefit the host.

PARASYMPATHETIC NERVOUS SYSTEM.

A branch of the autonomic nervous system that tends to induce secretion, increase the tone and contraction of smooth muscle, and cause dilation of blood vessels.

PARESIS.

Partial or total loss of movement or sensation.

PARESTHESIA.

An abnormal sensation often described as burning, tickling, tingling, or "pins and needles."

PARIETAL LOBE.

One of two brain hemispheres responsible for associative processes.

PARKINSONIAN.

Related to symptoms associated with Parkinson's disease, a nervous system disorder characterized by abnormal muscle movement of the tongue, face, and neck; inability to walk or move quickly; walking in a shuffling manner; restlessness; or tremors.

PARKINSONISM.

A set of symptoms originally associated with Parkinson's disease that can occur as side effects of neuroleptic medications. The symptoms include trembling of the fingers or hands, a shuffling gait, and tight or rigid muscles.

PARTIAL SEIZURE.

An episode of abnormal activity in a specific part of the brain that causes changes in attention, movement, or behavior.

PATHOGEN.

A disease-causing organism.

PATHOPHYSIOLOGY.

The changes in body functions associated with a disorder or disease.

PENETRANCE.

The degree to which individuals possessing a particular genetic mutation express the trait that this mutation causes. One hundred percent penetrance is expected to be observed in truly dominant traits.

PENETRATING HEAD INJURY.

Traumatic brain injury (TBI) in which an object pierces the skull and enters brain tissue.

PENICILLAMINE.

A drug used to bind to and remove heavy metals (such as copper or lead) from the blood, to prevent kidney stones, and to treat rheumatoid arthritis. Brand names include Cuprimine and Depen.

PERCUTANEOUS ABLATION.

Attempting to remove a foreign body by a method just above the skin, like using an ointment.

PERILYMPH.

The fluid that lies between the membranous labyrinth of the inner ear and the bony labyrinth.

PERIPHERAL NERVES.

Nerves outside the brain