Definition A cataract is a cloudiness or opacity in the normally transparent crystalline lens of the eye. This cloudiness can cause a decrease in vision and may lead to eventual blindness. Description The human eye has several parts. The outer layer of the eyeball consists of a transparent dome-shaped cornea and an opaque, white sclera. The cornea and sclera help protect the eye. The next layer includes the...

Definition Cataract surgery is a procedure performed to remove a cloudy lens from the eye; usually an intraocular lens is implanted at the same time. Purpose The purpose of cataract surgery is to restore clear vision. It is indicated when cloudy vision due to cataracts has progressed to such an extent that it interferes with normal daily activities. It is one of the most commonly performed surgical procedures...

Definition Cat-scratch disease is an uncommon infection that typically results from a cat’s scratch or bite. Most sufferers experience only moderate discomfort and find that their symptoms clear up without any lasting harm after a few weeks or months. Professional medical treatment is rarely needed. Description Cat-scratch disease (also called cat-scratch fever) is caused by the Bartonella henselae...

Treatment The choice of treatment for carpal tunnel syndrome depends on the severity of the symptoms and any underlying disease that might be causing the symptoms. Initial treatment usually includes rest, immobilization of the wrist in a splint, and occasionally ice application. Patients whose occupations are aggravating the symptoms should modify their activities. For example, computer keyboards and chair...

Causes For most patients, the cause of their carpal tunnel syndrome is unknown. Any condition that exerts pressure on the median nerve at the wrist can cause carpal tunnel syndrome. Common conditions that can lead to carpal tunnel syndrome include obesity, pregnancy,  hypothyroidism, arthritis, diabetes, and trauma. Tendon inflammation resulting from repetitive work, such as uninterrupted typing, can...

Definition Carpal tunnel syndrome is a disorder caused by compression at the wrist of the median nerve supplying the hand, causing numbness and tingling. Description The carpal tunnel is an area in the wrist where the bones and ligaments create a small passageway for the median nerve. The median nerve is responsible for both sensation and movement in the hand, in particular the thumb and first three fingers....

Carpal Tunnel Syndrome Overview Carpal tunnel syndrome is a disease of the hand characterized by numbness, tingling, pain, and weakness. The disease typically affects the thumb, index, and middle fingers and is often particularly troublesome at night. A major nerve, specifically the median nerve, travels down the arm and enters the hand through the carpal tunnel, which is located in the central part of the...

Definition Carotid sinus massage involves rubbing the large part of the arterial wall at the point where the common carotid artery, located in the neck, divides into its two main branches. Purpose Sinus, in this case, means an area in a blood vessel that is bigger than the rest of the vessel. This is a normal dilation of the vessel. Located in the neck just below the angle of the jaw, the carotid sinus...

Definition Cardiac tamponade occurs when the heart is squeezed by fluid that collects inside the sac that surrounds it.   Description The heart is surrounded by a sac called the pericardium. When this sac becomes filled with fluid, the liquid presses on the heart, preventing the lower chambers of the heart from properly filling with blood.   Because the lower chambers (the ventricles) cannot...

Definition Cardiac rehabilitation is a comprehensive exercise, education, and behavioral modification program designed to improve the physical and emotional condition of patients with heart disease.   Purpose Heart attack survivors, bypass and angioplasty patients, and individuals with angina, congestive heart failure, and heart transplants are all candidates for a cardiac rehabilitation program....

Definition Cardiac catheterization (also called heart catheterization) is a diagnostic procedure which does a comprehensive examination of how the heart and its blood vessels function. One or more catheters is inserted through a peripheral blood vessel in the arm (antecubital artery or vein) or leg (femoral artery or vein) with x–ray guidance. This procedure gathers information such as adequacy...

It takes three kinds of sensation to keep a person informed on movements of his body: sensations from the eyes (vision); from the muscles, joints, and tendons; and from his semicircular canals. When a person receives conflicting sensations regarding the movements of his body, as when the semicircular canals register movement and the other sensations indicate no movement, the result is dizziness. The semicircular...

The term" chills and fever" describes two conditions-one in which body temperature is rising and the person feels chilly while his fever is developing, and the other in which body temperature rises and falls in cycles, as is typical of malaria. When sweating occurs, the fever typically wanes.

Protrusion of the lining of the rectum occurs chiefly in infants and in elderly persons. The immediate cause is straining at stool or (in the more serious cases) merely coughing or engaging in muscular exertion as lifting. The condition becomes serious if the tissue is allowed to remain in the prolapsed condition long enough for it to be damaged from reduced blood supply. The tissue may be returned...

Definition A cardiac blood pool scan is a non-invasive test that uses a mildly radioactive marker to observe the functioning of the left ventricle of the heart.   Purpose The left ventricle is the main pump for distributing blood through the body. A cardiac blood pool scan is used to determine how efficiently the left ventricle is working. The scan can detect aneurysms of the...

Definition The carcinoembryonic antigen (CEA) test is a laboratory blood study. CEA is a substance which is normally found only during fetal development, but may reappear in adults who develop certain types of cancer.     Purpose The CEA test is ordered for patients with known cancers. The CEA test is most commonly ordered when a patient has a cancer of the gastrointestinal system. These...

Definition Carbon monoxide (CO) poisoning occurs when carbon monoxide gas is inhaled. CO is a colorless, odorless, highly poisonous gas that is produced by incomplete combustion. It is found in automobile exhaust fumes, faulty stoves and heating systems, fires, and cigarette smoke. Other sources include woodburning stoves, kerosene heaters, improperly ventilated water heaters and gas stoves, and blocked...

Definition Carbohydrate intolerance is the inability of the body to completely process the nutrient carbohydrate (a classification that includes sugars and starches) into a source of energy for the body, usually because of the deficiency of an enzyme needed for digestion. Lactose intolerance, the inability to digest the sugar found in milk, is widespread and affects up to 70% of the world’s adult...

Definition Canker sores are small sores or ulcers that appear inside the mouth. They are painful, self-healing, and can recur. Description Canker sores occur on the inside of the mouth, usually on the inside of the lips, cheeks, and/or soft palate. They can also occur on the tongue and in the throat. Often, several canker sores will appear at the same time and may be grouped in clusters. Canker sores appear...

Definition Candidiasis is an infection caused by a species of the yeast Candida, usually Candida albicans. This is a common cause of vaginal infections in women. Also, Candida may cause mouth infections in people with reduced immune function, or in patients taking certain antibiotics. Candida can be found in virtually all normal people but causes problems in only a fraction. In recent years, however, several...

Rachel Fuller Brown was born on November 23, 1898 in Springfield, Massachusetts. Brown was the oldest of two children born to Annie (Fuller) and George Hamilton Brown. In 1912, her father left their family in Missouri and her mother moved the family back to Springfield. Brown double majored in history and chemistry at Mount Holyoke, receiving her A.B. degree in 1920. She also earned her M.A. degree from...

Definition Supportive cancer therapy is the use of medicines to counteract unwanted effects of cancer treatment. Purpose Along with their beneficial effects, many cancer treatments produce uncomfortable and sometimes harmful side effects. For example, cancer drugs may cause nausea or vomiting. They also may destroy red or white blood cells, resulting in a low blood count. Fortunately, many of these side...

Definition Palliative cancer therapy is treatment specifically directed to help improve the symptoms associated with terminal cancer.  Purpose Palliative care is directed to improving symptoms associated with incurable cancer. Care can include surgery, radiation therapy, chemotherapy, symptomatic treatments resulting from cancer, and side effects of treatment. The primary objective of palliative...

According to nutritionists and epidemiologists from leading universities in the United States, a person can reduce the chances of getting cancer by following some simple guidelines: *eating plenty of vegetables and fruits *exercising vigorously for at least 20 minutes every day *avoiding excessive weight gain *avoiding tobacco (even second hand smoke) *decreasing or avoiding consumption of animal fats and...

‘‘Lifetime risk’’ is the term that cancer researchers use to refer to the probability that an individual over the course of a lifetime will develop cancer or die from it. In the United States, men have a one in two lifetime risk of developing cancer, and for women the risk is one in three. Overall, African Americans are more likely to develop cancer than whites. African Americans are...

There are a multitude of alternative treatments available to help the person with cancer. They can be used in conjunction with, or separate from, surgery, chemotherapy, and radiation therapy. Alternative treatment of cancer is a complicated arena and a trained health practitioner should be consulted. Although the effectiveness of complementary therapies such as acupuncture in alleviating cancer pain has not...

Treatment and prevention of cancers continue to be the focus of a great deal of research. In 2003, research into new cancer therapies included cancertargeting gene therapy, virus therapy, and a drug that stimulated apoptosis, or self-destruction of cancer cells, but not healthy cells. However, all of these new therapies take years of clinical testing and research. The aim of cancer treatment is to remove all...

Diagnosis begins with a thorough physical examination and a complete medical history. The doctor will observe, feel and palpate (apply pressure by touch) different parts of the body in order to identify any variations from the normal size, feel, and texture of the organ or tissue. As part of the physical exam, the doctor will inspect the oral cavity, or the mouth. By focusing a light into the mouth, he will...

Causes and symptoms The major risk factors for cancer are: tobacco, alcohol, diet, sexual and reproductive behavior, infectious agents, family history, occupation, environment and pollution. According to estimates of the American Cancer Society (ACS), approximately 40%of cancer deaths in 1998 were due to tobacco and excessive alcohol use. An additional one-third of the deaths were related to diet and nutrition....

  Cancer is the end product of a multistep process (carcinogenesis) that occurs over many years. The term "cancer" actually refers to numerous distinct diseases characterized by abnormal cell growth and differentiation. Cancers are categorized by the organ and/or cell of origin. For example, squamous cell carcinoma of the lung arises from pulmonary epithelial tissue, whereas adenocarcinoma of...

Definition Campylobacteriosis refers to infection by the group of bacteria known as Campylobacter. The term comes from the Greek word meaning ‘‘curved rod’’ referring to the bacteria’s curved shape. The most common disease caused by these organisms is diarrhea, which most often affects children and younger adults. Campylobacter infections account for a substantial percent of food-borne...

Definition Calcium channel blockers are medicines that slow the movement of calciuminto the cells of the heart and blood vessels. This, in turn, relaxes blood vessels, increases the supply of oxygen-rich blood to the heart, and reduces the heart’s workload. Purpose Calcium channel blockers are used to treat high blood pressure, to correct abnormal heart rhythms, and to relieve the type of chest...

Definition Caffeine is a drug that stimulates the central nervous system. Purpose Caffeine makes people more alert, less drowsy, and improves coordination. Combined with certain pain relievers or medicines for treating migraine headache, caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract...

Definition C-reactive protein (CRP) is a protein produced by the liver and found in the blood. Purpose C-reactive protein is not normally found in the blood of healthy people. It appears after an injury, infection, or inflammation and disappears when the injury heals or the infection or inflammation goes away. Research suggests that patients with prolonged elevated levels of C-reactive protein are at an increased...

Constipation: Summary Different people have different bowel movement patterns. These patterns vary depending on how much exercise you get, your lifestyle and your overall general health. Bowel activity is most influenced by how much insoluble fibre (such as wheat bran) you eat and fluids you drink. Some people will move their bowels 3 times daily, while other people may only move their bowels 3 times weekly....

Loss of weight is expected when a person goes on a reducing diet. But loss of weight under other circumstances is cause for alarm. Loss of weight occurs in acute diseases with fever or in any illness where food intake is sharply curtailed. Unexplained loss of weight is one of the signs that should call attention to the possibility of cancer. Loss of weight may not be the first telltale evidence of cancer, however....

In about 75 percent of women there develops a tendency to nausea and vomiting, usually in the mornings during the fifth to the sixteenth weeks of pregnancy. The symptom is most noticeable with the first pregnancy. The cause is not well-understood. In about one case in 200 the symptom is severe, requiring hospital care.  

Varicose veins are veins which have become lengthened, enlarged, and "knotty" in appearance. The change occurs commonly in the surface veins of the legs. As such a vein lengthens, it becomes tortuous. Varicose veins may be caused by any factor which retards the flow of blood through the veins involved. Varicose veins occur more commonly in some families than in others. Pressure against the pelvic...

A. Difficult Urination (Dysuria). Difficulty in the voiding of urine may come from conditions involving the urethra, such as stricture following an old infection, or from pressure from outside the urethra as by an enlarged prostate. It can occur as a consequence of taking certain drugs. Cystitis (inflammation of the lining of the bladder) may cause a spasm of the muscle that normally keeps the outlet of the...

An ulcer of the skin is a lesion in which an area of skin and a certain amount of underlying tissues has been destroyed. It differs from an ordinary wound in that the vitality of the tissue is less than normal and healing is delayed. The usual reasons for lowered tissue vitality are a reduction in blood or nerve supply or the presence of infection. Common manifestations of ulcers of the skin are as follows: A....

See Hearing, Disturbances of Tinnitus is commonly called "ringing in the ears" or "ear noise." It is different from auditory hallucinations (see Hearing, Disturbances of). Tinnitus consists of a sensation of noise, hissing, ringing, buzzing, thumping, whistling, or roaring, and is often associated with partial deafness. Tinnitus is caused by an irritation, and thus an abnormal stimulation,...

Emotional tensions occur in persons ill at ease or baffled by problems seemingly too difficult to solve. In some cases the person knows, at the level of intellect, what he should do but is deterred by his emotions (fear, love, hate) from acting. In other cases moving in the sensible direction would require him to forfeit some cherished desire; so emotional pressures build up while the solving of the problem...

Swallowing is a complicated function involving coordination of muscles of the face, the tongue, the pharynx, and the esophagus. These muscles are under the control of five pairs of nerves and the corresponding integration centers of the brain. Difficulty in swallowing is commonly caused, of course, by disease, obstruction, or compression of the esophagus. But it may also be caused by faulty nerve control or...

In susceptible persons, temporary injury to the skin, similar to what is caused by excessive heat, results from exposure to the ultraviolet rays of sunlight. The degree of injury to the skin depends on the concentration of ultraviolet rays in the sunlight, on the duration of the exposure, and on the amount of pigment within the skin of the individual. Blonds and redheads are particularly susceptible. On repeated...

See Coma |  Fainting| Shock. In stupor there is a reduction of alertness, a semi-consciousness from which the patient can be partially aroused. Stupor may represent a mild degree of coma or shock. It may progress to more severe coma or shock or unconsciousness. It may occur, then, in a person under the influence of drugs or seized by an attack of epilepsy. In cases of mental illness, the term stupor describes...

A. Disturbances in the Speech Area of the Brain. Various parts of the brain are involved in the use of  language, the sensory areas of hearing and vision, the area in which memories are recorded, the area in which imagination and creative thinking occur, and the areas in which the muscle actions are coordinated and initiated. These areas, interconnected by many nerve fibers, function smoothly in enabling...

Sore throat may be the result of local irritation of the pharynx, as from drinking irritating or excessively hot fluids, from smoking tobacco, or from using concentrated mouthwashes or antiseptic gargles. Sore throat is a frequent prelude to the common cold. As such, the irritation is caused by an invasion of the pharynx by the responsible virus and by the common types of germs (other than viruses) that infest...

Soreness is a local condition of discomfort produced by mild pressure or manipulation. The term "soreness" commonly refers to a localized condition in which relatively little discomfort is felt except under pressure or movement. In "pain" the discomfort is spontaneous. Soreness occurs in inflamed tissues, as in bruises, infections, or abscesses, or in overused muscles.

Sneezing is a natural reflex action intended to aid in the expelling of an irritant from the nasal passages. Nasal irritants commonly consist of dust or powders- pepper, for instance. The membranes lining the nasal passages can also be irritated by anything that causes them to swell. The two commonest causes of such swelling are (1) infection, such as the common cold, and (2) allergy sensitivity to some foreign...

Some people lie awake for a long time after retiring, but when they do go to sleep, they sleep soundly. Some waken early and cannot go back to sleep. Others waken repeatedly during the night.  Sleep requirements vary from person to person. A few people seem to get along well on five or six hours per night. Others need nine or ten in order to maintain strength, energy, and alertness. It is wise, therefore,...