Glossary

a b c d e f g h i j k l m n o p q r s t u v w x y z
T

Take Assignment:

(Medicare) A term used to describe an agreement by a doctor to accept Medicare's approved amount as payment in full. Any doctor who is a "participating provider" in the Medicare program always takes assignment. Participating providers may not charge you more than Medicare's approved amount. If you have Original Medicare, it can save you money to see a doctor who takes assignment. But, you still pay your coinsurance (or share) of the cost of the doctor visit, usually 20 percent of the Medicare-approved amount. (See also Participating Provider.)

Tardive dyskinesia:

A movement disorder that may result from extended therapy with certain antipsychotic medications such as haloperidol. The condition is characterized by involuntary, rhythmic movements of the face, jaw, mouth, and tongue, such as lip pursing, chewing movements, or protrusion of the tongue. Facial movements are sometimes accompanied by involuntary, jerky or writhing motions (choreoathetoid movements) of the trunk, arms, and legs. In some patients, symptoms discontinue months or years after withdrawal of antipsychotic therapy. However, in others, the condition may not be reversible.

Tardive dystonia:

A form of tardive dyskinesia characterized by chronic dystonia due to administration of medications that block dopamine D2 receptors (dopamine receptor antagonists), such as certain antipsychotic agents. (Dopamine receptors are molecules on the surfaces of receiving nerve cells that are sensitive to stimulation by dopamine, a neurotransmitter that controls movement and balance. Several types of dopamine receptors have been identified, including D1, D2, and D3.) Dystonia is a neurologic movement disorder characterized by sustained muscle contractions that often result in repetitive twisting motions or unusual postures or positions. Tardive dystonia is the most common form of secondary dystonia--i.e., dystonia that results from certain environmental factors or "insults" that affect the brain. In adults, tardive dystonia often initially affects facial or neck muscles. Dystonia may remain limited to such regions or extend to affect adjacent muscles of the trunk and arms. Children are more likely to be affected by generalized dystonia that involves muscles of the trunk and legs.

Tauopathy:

Any group of diseases that cause dementia related to a problem with tau, a protein that is important in maintaining the structure of brain cells.

Tay-Sachs disease:

A progressive neurodegenerative metabolic disorder that belongs to a group of diseases called lysosomal storage diseases. Also known as GM2 gangliosidosis type I or infantile type, Tay-Sachs disease results from deficiency of the enzyme hexosaminidase A, which leads to an abnormal accumulation of certain fats (i.e., gangliosides) in particular tissues, particularly nerve cells of the brain. An autosomal recessive disorder, Tay-Sachs disease primarily affects individuals of northeastern European Jewish (Ashkenazi Jewish) ancestry. Symptom onset typically begins from about 3 to 6 months of age. Associated symptoms may include an exaggerated startle response, increasing listlessness, loss of previously acquired skills (psychomotor regression), severely diminished muscle tone (hypotonia), and the development of characteristic, cherry-red circular areas within the middle layers of the eyes (Tay's sign). With disease progression, affected infants and children may develop increasing muscle stiffness or rigidity; seizures; sudden, involuntary, "shock-like" contractions of multiple muscle groups in response to certain stimuli (generalized, stimuli-sensitive myoclonus); enlargement of the brain (metabolic megalencephaly); deafness; blindness; and dementia. Life-threatening complications may develop between 2 to 5 years of age.

T cells:

Cells that orchestrate immune activity by means of specific receptors for antigens, commands to other immune cells, and the production of cytokines.

Tendon:

A tough fibrous cord of tissue that attaches muscle to bone (or other structures of the body).

Teratogenic:

Possessing the ability to disrupt normal fetal development and causing fetal abnormalities.

Testosterone:

A hormone made by the testicles and adrenal glands, and also in various cells of the body, that promotes masculine traits.

Th1 cells:

Helper T cells that enhance the body’s inflammatory response.

Th2 cells:

Helper T cells that suppress abnormal immune reactions in the body.

Thalamotomy:

Operation in which a small region of the thalamus is destroyed, achieved by stereotactic techniques. Tremor and rigidity in Parkinsonism and other conditions may be relieved by thalamotomy.

Thalamus:

(1) Anatomical term designating a mass of grey matter centrally placed deep in the brain near its base and serving as a major relay station for impulses travelling from the spinal cord and cerebellum to the cerebral cortex. (2) A crucial area of the brain consisting of two relatively large masses gray matter. The thalamus receives and processes messages from the body regarding heat, cold, pain, pressure, smell, taste, and movement. Input from all the sensory organs (expect smell) enter the deeper areas of the brain through the thalamus. In addition, the thalamus is crucial to sensorimotor function.

Threshold:

A pain threshold is the point at which a feeling or sensation becomes painful.

Thrombosis:

A blood clot that forms inside a blood vessel. When it occurs in a neck or brain artery, it can cause ischemic stroke.

Thromboxane:

A group of compounds biochemically related to the prostaglandins and initially made from fatty acids. Different fatty acids lead to different thromboxanes, and each type of thromboxane has a different action. For instance, thromboxane B-2 can induce clot formation.

Thymus:

A gland located at the base of the neck. T cells mature in the thymus, making it a critical part of a normally-functioning immune system.

Tics:

Involuntary, compulsive, stereotypic muscle movements or vocalizations that abruptly interrupt normal motor activities. These repetitive, purposeless motions (motor tics) or utterances (vocal tics) may be simple or complex in nature; may be temporarily suppressed; and are often preceded by a "foreboding" sensation or urge that is temporarily relieved following their execution. Simple tics include abrupt, isolated movements, such as repeated facial twitching, blinking, or shoulder shrugging, and simple sounds, including grunting, throat clearing, or sighing. Complex tics may involve more sustained, complex movements, such as deep knee bending or leg kicking, or complex vocalizations, including repeating another person's words or phrases (echolalia) or, rarely, explosive cursing (coprolalia). Tourette syndrome is defined as the presence of multiple motor and vocal tics for at least one year, changes in the nature of the tics (e.g., complexity, severity, anatomical location) during the course of the disorder, and symptom onset before age 21.

Tone:

Resistance or tension in a muscle when a limb or other body part is moved passively and in a relaxed state about a joint. A state of muscle tension balanced by partial contraction or alternate contraction and relaxation.

TorsinA:

A protein that, when defective, may cause DYT-1 dystonia. Although its exact function is not known, TorsinA is believed to be related to a series of compounds that enable cells to recover from stress and injury.

Toxic or Toxin:

A poisonous substance that can damage living cells and tissue inside the body. Toxins can enter the body from the outside environment (drugs, alcohol, pollution) or they can be produced inside the body as waste by-products of metabolism.

Toxic Metabolites:

Potentially harmful substances formed as the result of normal body functions.

Trans-Fatty Acids:

Fatty acids that have been altered by food processing and take on abnormal shapes not normally useful to the body.

Transdermal:

Transdermal means, literally, through the skin.

Transient:

Temporary; transitory; not lasting or enduring.

Transient ischemic attack (TIA):

A temporary blockage of blood to the brain that indicates that a more severe episode or stroke may occur in the future.

Tremor:

Rhythmic, involuntary, oscillatory (or to-and-fro) movements of a body part as a result of sequential muscle contractions.

TRICARE for Life:

The health care program for military retirees who have served honorably for at least 20 years. They must be enrolled in Part B to receive the benefits. It pays secondary to Medicare and covers out-of-pocket expenses including deductibles and coinsurance. People who qualify can receive free or low-cost medications from military treatment facilities, TRICARE network and non-network pharmacies, and the National Mail Order Pharmacy.

Triglyceride:

A type of fat that circulates in the bloodstream. A glycerol molecule forms the backbone to which one, two, or three fatty acids attach. High blood triglyceride levels can lead to atherosclerosis (blockage of arteries).

Tripeptide:

A substance made from three amino acids.

Triptans:

A class of prescription drugs used to treat severe migraine.

Tropical spastic paraparesis (HTLV-1-associated myelopathy):

A rare disorder characterized by slowly progressive weakness (paraparesis), stiffness (rigidity), and spasticity of the leg muscles due to infection with the human T-cell lymphotropic virus-1 (HTLV-1). Modes of transmission include sexual contact, mother-to-child transmission (e.g., via breastfeeding), and blood transfusion.

Tumeric:

A spice with anti-inflammatory effects. The active ingredient is curcumin, which has antioxidant and anti-inflammatory properties. Tumeric is a common ingredient in curry powder.

Tyrosine:

An aromatic nonessential amino acid that is a metabolic precursor of thyroxine, the pigment melanin, and other biologically important compounds.

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Document last modified: 04/22/09 12:19:44 PM