Definition Dysphasia is a partial or complete impairment of the ability to communicate resulting from brain injury. Description Approximately one million Americans currently suffer from one of the various forms of dysphasia, and an additional 80,000 new cases occur annually. The term "dysphasia" is more frequently used by European health professionals, whereas in North American the term, aphasia is...

Definition Dysmenorrhea refers to the pain or discomfort associated with menstruation . Although not a serious medical problem, the term describes a woman adolescent girl with menstrual symptoms severe enough to keep her from functioning for a day or two each month. Description Menstrual cramps are a common problem for adolescent girls and women. They may be mild, moderate, or severe...

Definition Dyslexia is an unexpected impairment in reading and spelling despite a normal intellect. Description Dyslexia was first described by Hinshelwood in 1896. Orton originally hypothesized that dyslexiaresults from a dysfunction in visual memory and visual perception due to a delayment in maturation. Most dyslexics also display poor writing ability. Dyslexia is a classical primary...

  Definition Dysfunctional uterine bleeding is irregular, abnormal uterine bleeding that is not caused by a tumor, infection, or pregnancy. Description Dysfunctional uterine bleeding (DUB) is a disorder that occurs most frequently in women at the beginning and end of their reproductive lives. About half the cases occur in women over 45 years of age, and...

Definition Dysentery is a general term for a group of gastrointestinal disorders characterized by inflammation of the intestines, particularly the colon. Characteristic features include abdominal pain and cramps, straining at stool (tenesmus), and frequent passage of watery diarrhea or stools containing blood and mucus. The English word dysentery comes from two Greek words...

Definition Duodenal obstruction is a partial or complete obstruction of the duodenum, the first part of the small intestine. Obstruction prevents food from passing through the digestive tract, interfering with digestion and nutrition . Description The duodenum is the first part of the small intestine, extending from the valve at the bottom of the stomach that regulates...

Definition Dry mouth, known medically as xerostomia, is the abnormal reduction of saliva due to medication, disease, or medical therapy. Description Dry mouth due to the lack of saliva can be a serious medical problem. Decreased salivation can make swallowing difficult, decrease taste sensation, and promote tooth decay. Causes & symptoms Dry mouth, resulting from thickened or reduced...

Definition These drugs are used to induce (start) or continue labor. Purpose The drug decribed here, oxytocin, makes the uterus (womb) contract. Physicians use it to deliberately start labor. Because there are some risks with using oxytocin, this should be done only when there are good medical reasons. Any woman who is being given oxytocin should make sure she has discussed the...

Definition Drug therapy monitoring, also known as Therapeutic Drug Monitoring (TDM), is a means ofmonitoring drug levels in the blood. Purpose TDM is employed to measure blood drug levels so that the most effective dosage can be determined, with toxicity prevented. TDM is also utilized to identify non compliant patients (those patients who, for whatever reason, either...

Definition A drug overdose is the accidental or intentional use of a drug or medicine in an amount that is higher than is normally used. Description All drugs have the potential to be misused, whether legally prescribed by a doctor, purchased over-the-counter at the local drug store, or bought illegally on the street. Taken in combination with other drugs or with alcohol, even...

Definition Drug metabolism is the process by which the body breaks down and converts medication into active chemical substances. Precautions Drugs can interact with other drugs, foods, and beverages. Interactions can lessen or magnify the desired therapeutic effect of a drug, or may cause unwanted or unexpected side effects. There are thousands of possible drug-to-drug and drug-to-food interactions,...

Definition Down syndrome (DS) is  the most common cause of mental retardation and malformation in a newborn. It occurs because of the presence of an extra chromosome. It was first described in 1866 by Dr. John L. H. Down (1828–1896), an English physician. Down syndrome occurs about once in every 800 births. It is estimated that about 6,000 children are born with DS each year...

  Definition Doppler ultrasonography, also called Doppler ultrasound, is a noninvasive diagnostic procedure that uses an ultrasound scanner to convert sound waves into images of blood flow in body tissue and organs. Doppler ultrasonography does not use ionizing radiation and is used for a variety of clinical applications. Purpose Doppler ultrasonography is...

  Definition Dizziness is classified into three categories—vertigo, syncope, and nonsyncope nonvertigo. Each category has a characteristic set of symptoms, all related to the sense of balance. In general, syncope is defined by a brief loss of consciousness (fainting) or by dimmed vision and feeling uncoordinated, confused, and lightheaded. Many people experience a sensation like syncope when...

Definition Diverticulosis refers to a condition in which the inner, lining layer of the large intestine(colon) bulges out (herniates) through the outer, muscular layer. These outpouchings are called diverticula. Diverticulitis refers to the development of inflammation and infection in one or...

Definition Diuretics are medicines that help reduce the amount of water in the body.  Purpose Diuretics are used to treat the buildup of excess fluid in the body that occurs with some medical conditions such as congestive heart failure, liver disease, and kidney disease. Some diuretics are also prescribed to treat high blood pressure. Most of these drugs act on the kidneys to increase...

  Definition The dissociative disorders are a group of mental disorders that affect consciousness defined as causing significant interference with the patient's general functioning, including social relationships and employment. Description In order to have a clear picture of these disorders, dissociation should first be understood. Dissociation is a mechanism that allows...

Definition In medicine, the terms dislocation and subluxation refer to the displacement of bones that form a joint. These conditions affecting the joint most often result from trauma that causes adjoining bones to no longer align with each other. A partial or incomplete dislocation is called a subluxation. Description In a healthy joint, the bones are normally held together with tough, fibrous bands called ligaments....

  Definition One of the most common types of back surgery is disk removal (diskectomy), the removal of an intervertebral disk, the flexible plate that connects any two adjacent vertebrae in the spine. Intervertebral disks act as shock absorbers, protecting the brain and spinal cord from the impact produced by the body's movements. Purpose About 150,000 Americans undergo disk removal each...

Definition Discoid lupus erythematosus (DLE) is a disease in which coin-shaped (discoid) red bumps appear on the skin. Description The disease called discoid lupus erythematosus only affects the skin, although similar discoidskin lesions can occur in the serious disease called systemic lupus erythematosus (SLE). Only about 10% of all patients with...

Definition Diphtheria is potentially fatal, contagious disease that usually involves the nose, throat,and air passages, but may also infect the skin. Its most striking feature is the formation of agrayish membrane covering the tonsils and upper part of the throat. Description Like...

Definition Digitalis drugs are medicines made from a type of foxglove plant (Digitalis purpurea ) that have a stimulating effect on the heart. Purpose Digitalis drugs are used to treat heart problems such as congestive heart failure and irregular heartbeat. These medicines help make the heart stronger and more efficient. This, in turn, improves blood circulation and helps relieve...

Definition DiGeorge syndrome is a rare congenital disease that affects an infant's immune system and that is due to a large deletion from chromosome 22. The syndrome is marked by absence or underdevelopment of the thymus and parathyroid glands. It is named for the pediatrician who first described it in 1965. Normally the thymus gland is located below the thyroid gland in the neck and...

  Definition Diffuse esophageal spasm is a term used to define an uncoordinated or spastic esophagus. Description The esophagus is a muscular tube that actively transports food from the throat to the stomach by rhythmic contractions known as peristalsis. The actual mechanism and anatomy are quite complex, involving three distinct segments and allowing a person to swallow even when upside-down. Diffuseesophageal spasm describes...

Definition Humans may alter their usual eating habits for many reasons, including weight loss,disease prevention or treatment, removing toxins from the body, or to achieve a general improvement in physical and mental health. Others adopt special diets for religious reasons. In the case of some vegetarians and vegans, dietary changes are made out of ethical concerns for the rights of animals. Purpose People who...

  Definition To most individuals, diarrhea means an increased frequency or decreased consistency ofbowel movements; however, the medical definition is more exact than this. Diarrhea best correlates with an increase in stool weight; this increase is mainly due to excess water,...

Definition Diaphragms are dome-shaped barrier methods of contraception that block sperm from entering the uterus. They are made of latex (rubber) and formed like a shallow cup. Since vaginas vary in size, each patient will need to be fitted by a doctor or nurse with a diaphragm that conforms to the shape and contour of the vagina as well as the strength of the muscles in the vaginal walls....

Definition Dermatitis of the buttocks, genitals, lower abdomen, or thigh folds of an infant or toddler is calleddiaper rash. The outside layer of skin normally forms a protective barrier that prevents infection; when the barrier fails, the child may develop a rash in the area covered by the diaper. Diaperrashes occur equally with cloth diapers and disposable diapers. Description Diaper dermatitis...

Definition Diabetic neuropathy is nerve damage caused by diabetes. Description Diabetic neuropathy is a common complication of diabetes mellitus . The most common type of nerve damage associated with diabetes is known as peripheral neuropathy because it is a loss of sensation and strength in the hands and feet. Diabetic neuropathy can also affect the nerves...

Definition Diabetic foot infections are infections that can develop in the skin, muscles, or bones of the footas a result of the nerve damage and poor circulation that is associated with diabetes. Description People who have diabetes have a greater-than-average chance of developing foot infections. Because a person who has diabetes may not feel foot pain or...

The term "diabetes mellitus" represents a group of conditions characterized by abnormally high blood glucose levels (hyperglycemia). In 1997, nearly 16 million people in the United States haddiabetes; approximately 10.3 million were diagnosed with the conditions, while an estimated 5.4 million were undiagnosed. Diabetes may be complicated by uncontrolled hyperglycemia, and treateddiabetes may...

  Definition Diabetes insipidus (DI) is a disorder that causes the patient to produce excessive quantities of urine. The massively increased urine output is usually accompanied by intense thirst. Description Diabetes insipidus is usually the result of the body's inability to appropriately produce, store or release a hormone that increases water absorption by the kidneys and decreases...

Definition The nasal septum is a thin structure, separating the two sides of the nose. If it is not in the middle of the nose, then it is deviated. Description The nasal septum is composed of two parts. Toward the back of the head the nasal septum is rigid bone, but further forward the bone becomes cartilage. With one finger in each nostril this cartilage can easily be bent...

  Definition Detoxification is one of the more widely used treatments and concepts in alternativemedicine. It is based on the principle that illnesses can be caused by the accumulation oftoxic substances (toxins) in the body. Eliminating existing toxins and avoiding new toxins are essential parts of the healing process. Detoxification utilizes a variety of tests and techniques. Origins Detoxification methods...

Definition DES (diethylstilbestrol) is a hormone that was prescribed for pregnant women in the 1950s and early 1960s. Many years later, doctors discovered that the daughters of the women who received DESwere at high risk for a variety of problems, including infertility, premature labor, and cancer of the vagina and cervix. Description In the 1950s and early 1960s, several drug companies...

Definition Dermatomyositis is one member of a group of diseases that are collectively called inflammatory myopathies. A myopathy is a disorder of a muscle. Hallmarks of dermatomyositis disease are a widespread rash and muscle weakness. Description Dermatomyositis is characterized by the onset of symptoms that can be severe, with rash and muscle weakness occurring over a large portion...

Definition Dermatitis is an inflammation of the skin characterized by an itchy pink or red rash. There are various types of dermatitis including contact, stasis, and atopic dermatitis (also known as eczema). Description Dermatitis is not fatal or contagious but can be an uncomfortable condition. Contact dermatitis is an allergic reaction to something that irritates...

Definition Depression and depressive disorders (unipolar depression) are mental illnessescharacterized by a profound and persistent feeling of sadness or despair and/or a loss of interest in things that once were pleasurable. Disturbance in sleep , appetite, and mental processes are common symptoms of depression. Description Everyone...

Definition Norplant is a long-acting hormone that is inserted under the skin and prevents conceptionfor up to five years. Depo-Provera is also a hormone, but is administered by intramuscularinjection and provides protection against pregnancy for three months. Lunelle is...

Definition Dental trauma is injury to the teeth, gums, and jawbones. The most common dental trauma is a broken or displaced tooth. Description Dental trauma may be inflicted in a number of ways: contact sports , motor vehicle accidents, fights, falls, eating hard foods, drinking hot liquids, and other such mishaps. Dental trauma includes teeth that...

Definition   Dengue fever is a disease caused by one of a number of viruses that are carried bymosquitoes. These mosquitoes then transmit the virus to humans. Description The virus that causes dengue fever is called an arbovirus, which stands for arthropod-borne virus.Mosquitoes are a type of arthropod....

Definition Dementia is not a specific disorder or disease. It is a syndrome (group of symptoms) associated with a progressive loss of memory and other intellectual functions that is serious enough to interfere with performing the tasks of daily life. Dementia can occur to anyone at any age from an injury or from oxygen deprivation, although it is most commonly associated with aging. It is the...

Description A delusion is a belief that is clearly false and that indicates an abnormality in the affected person’s content of thought. The false belief is not accounted for by the person’s cultural or religious background or his or her level of intelligence. The key feature of a delusion is the degree to which the person is convinced that the belief is true. A person with a delusion will hold firmly...

Definition Delirium is a transient, abrupt, usually reversible syndrome characterized by a disturbance that impairs consciousness, cognition (ability to think), and perception. Description The word delirium is derived from the Latin delirare which literally translates "to go out of the furrow." Delirium is typically an acute change in thinking with a disturbance in...

  Definition A delayed hypersensitivity test (DHT) is an immune function test measuring the presence of activated T cells that recognize a certain substance. Purpose The immune system protects against infection by viruses, bacteria, fungi, and parasites. After initial exposure to a foreign substance, or antigen, the immune system creates both antibodies and sensitized T cells....

Definition Dehydration is the loss of water and salts that are essential for normal body function. Description Dehydration occurs when the body loses more fluid than it takes in. Dehydration can upset the delicate fluid-salt balance needed to maintain healthy cells and tissues. The human body is generally over 60 percent water. The body works to maintain water balance through mechanisms such...

Definition Defibrillation is a process in which an electrical device called a defibrillator sends an electric shock to the heart to stop an arrhythmia resulting in the return of a productive heart rhythm.  Purpose Defibrillation is performed to correct life-threatening arrhythmias of the heart including ventricular fibrillation and cardiac arrest. In cardiac emergencies it should be performed...

Definition Deep vein thrombosis (DVT) is a blood clot in a major vein, usually in the legs and/or pelvis. Description Deep vein thrombosis is a common but difficult to detect illness that can be fatal if not treated effectively. According to the American Heart Association, more than two million Americans developdeep vein thrombosis annually. An estimated 600,000...

Definition Decongestants are medicines used to relieve nasal congestion (stuffy nose). Purpose A congested or stuffy nose is a common symptom of colds and allergies. This congestion results when membranes lining the nose become swollen. Decongestants relieve the swelling by narrowing the blood vessels that supply the nose. This reduces the blood supply to the swollen membranes, causing...

  Definition Decompression sickness (DCS) is a dangerous and occasionally lethal condition caused by nitrogen bubbles that form in the blood and other tissues of scuba divers who surface too quickly. It also occurs in the blood of tunnelers or miners who work in conditions of increased pressure and return to normal atmospheric pressure too quickly. Description According to the Divers Alert Network (DAN),...