Glossary Index by Letter

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Dexamethasone. A glucocorticosteroid medication used to reduce brain tissue swelling. Also used, in low doses, to treat adrenal insufficiency.


Refers to a surgical procedure during which bone, tissue, or tumor is removed to lessen intracranial pressure. Decompressive craniectomy is an advanced treatment option for intracranial pressure (ICP) control in patients with traumatic brain injury.


A mature cell returning to a less mature state. See differentiate, undifferentiated. In cancer, refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread at a slower rate than...


The amount of darkness or light in an area of a scan reflects the compactness and density of tissue. The amount of darkness or light in an area of a scan reflects the compactness and density of tissue. Differences in tissue density are the basis for CT and MR...


Dual-energy X-ray absorptiometry. A technique used to measure bone mineral density, but which can also be used to measure body composition. Dual Energy X-Ray Absorptiometry (DEXA) is a test that uses x-rays to measure the thickness of the bones in the hip, spine,...

Diabetes (Diabetes Insipidus)

A problem with water balance in the body causing excess urine production and great thirst, due to pituitaryhypothalamic damage. Diabetes mellitus, which has the same symptoms, is due to insufficient insulin production by the pancreas. Diabetes Insipidus symptoms...

Diabetes (Diabetes Mellitus)

A metabolic disease in which carbohydrate utilization is reduced and that of lipid and protein enhanced; it is caused by an absolute or relative deficiency of insulin and is characterized, in more severe cases, by chronic hyperglycemia, glycosuria, water and...


An expert in the practical application of diet in the prevention of disease or of a process that can lead to disease, and in the treatment of disease. Plan and conduct food-service or nutritional programs to assist in the promotion of health and disease control. May...


The process cells undergo as they mature into normal cells. Differentiated cells have distinctive characteristics, perform specific functions, and are less likely to divide. See dedifferentiate, undifferentiated.


Lacking a distinct border, not localized, spread out. Opposite of circumscribed. Widely spread; not localized or confined. Example: Cancer treatment depends on whether the tumor is diffuse (spread throughout the brain) or focal (in one area of the brain).


Double vision. Diplopia is a vision disorder in which two images of a single object are seen, caused from unequal action of the eye muscles.

Dopamine Agonists

Medications with predominant effects on pituitary cells that harbor receptors for the chemical transmitter dopamine. Examples include Bromocriptine and Cabergoline.

Doppler Ultrasonography

An application of diagnostic ultrasound used to detect moving blood cells or other moving structures and measure their direction and speed of movement. The Doppler effect is used to evaluate movement by measuring changes in frequency of the echoes reflected from...


An accumulation of an excessive amount of watery fluid in cells, tissues, or serous cavities (swelling). Edema means swelling by an excessive amount of watery fluid accumulated in the intercellular spaces, most commonly present in subcutaneous tissue. It usually...


Enzyme-linked immunosorbent assay. ELISA stands for enzyme-linked immunosorbent assay. It is a commonly used laboratory method to detect antibodies in the blood as a result of being exposed to viruses or other infectious substances.

Embolus, pl. Emboli, Embolism

A plug, composed of a detached blood clot, mass of bacteria, or other foreign body, blocking a vessel. A thrombus that travels from the blood vessel or heart to another location in the body is called an embolus. The disorder is called an embolism. For example, an...


Vomiting. Vomiting, stomach upset, or Nausea is a complex, coordinated reaction orchestrated by the brain responding to signals coming from the mouth, stomach, intestines, bloodstream, balacing systems in the ear (motion sickness), or due to unsettling sights, smells...


Confined to a specific, localized area and surrounded by a thin layer of tissue. Refers to a tumor that is wholly confined to a specific area, surrounded by a capsule. Localized.


Radiographic representation of the brain. Encephalography is the examination of the brain by radiography after the withdrawal of cerebrospinal fluid (by lumbar or cisternal puncture) and introduction of air, another gas, or contrast material. Electroencephalography...

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