3/13/15

Chronic fatigue syndrome

The Chronic fatigue syndrome - A condition causing extreme fatigue over a prolonged period, often over years. It is most common in women aged between 25 and 45.

The cause of the condition is unclear. In some cases, it develops after recovery from a viral infection or after an emotional life event such as bereavement.

In other cases, there is no such preceding illness or event. The main symptom is persistent tiredness. Other symptoms of the syndrome vary, but commonly include impairment of short-term memory or concentration, sore throat, tender lymph nodes, muscle and joint pain, muscle fatigue, unrefreshing sleep, and
headaches.

The syndrome is often associated with depression or anxiety. There is no specific diagnostic test for chronic fatigue syndrome, and investigations are usually aimed at excluding other possible causes of the symptoms, such as anaemia.

A physical examination, blood tests, and psychological assessment may be carried out. If no cause can be found, diagnosis of chronic fatigue syndrome is made from the symptoms.

Analgesic drugs or antidepressant drugs may relieve the symptoms. Physiotherapy or psychotherapy may also be helpful. Chronic fatigue syndrome is a longterm disorder, but the symptoms clear up after several years in some people.
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Chromosomes

SET OF HUMAN CHROMOSOMES
The Chromosomes - Thread-like structures in the nuclei of cells. Chromosomes carry inherited information in the form of genes, which govern all cell activity and function.

Each chromosome contains up to several thousand genes arranged in single file along a long double filament of DNA. The sequence of chemical units, or bases, in the DNA provides the coded instructions for cellular activities.

All an individual’s body cells (with the exception of egg or sperm cells) carry precisely the same chromosomal material copied by a process of cell division from the original material in the fertilized egg. Each human cell normally contains 46 chromosomes made up of 23 pairs.

Half of each pair is of maternal and half of paternal origin. 22 pairs are autosomal chromosomes, which are the same in both sexes; the remaining pair is made up of 2 sex chromosomes.

In females, the sex chromosomes are a pair of X chromosomes. In males, 1 is an X chromosome and the other is a Y chromosome. One sex chromosome (an X) originates from the mother’s egg and the other (an X in girls; a Y in boys) from the father’s sperm.
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Chromosome analysis

The Chromosome analysis - Study of the chromosomes in body cells to discover whether a chromosomal abnormality is present or to establish its nature. Fetal cells for analysis can be obtained in the uterus by amniocentesis or chorionic villus sampling.

If a serious abnormality such as Down’s syndrome is identified, termination of the pregnancy and genetic counselling is offered. Chromosome analysis is also carried out when a baby is stillborn without an obvious cause, or is born with abnormal physical characteristics that suggest a chromosomal defect, such as Turner’s sydrome.

Chromosome analysis in children and adults uses white blood cells taken from a blood sample. Analysis of the sex chromosomes may be carried out to establish the chromosomal sex of a child in cases where the genitals have an ambiguous appearance (see genitalia, ambiguous); to confirm or exclude the diagnosis of chromosomal abnormalities; or to investigate infertility.

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Chromosomal abnormalities

The Chromosomal abnormalities - Variations from normal in the number or structure of chromosomes contained in a person’s cells. The cause is generally a fault in theprocess of chromosome division, either during the formation of an egg or sperm, or during the first few divisions of a fertilized egg.

Chromosomal abnormalities are classified according to whether they involve the 44 autosomes or the 2 X and Y sex chromosomes. A complete extra set of chromosomes per cell is called polyploidy and is lethal.

Autosomal abnormalities cause physical and mental defects of varying severity. Some types of autosomal abnormality, known as trisomy, consist of an extra chromosome on 1 of the 22 pairs of autosomes.

The most common trisomy is Down’s syndrome. Sometimes, part of a chromosome is missing, as in cri du chat syndrome. In translocation, a part of a chromosome is joinedto another, causing no ill effects in the person but a risk of abnormality in his or her children.

Sex chromosome abnormalities include Turner’s syndrome, in which a girl is born with a single X chromosome in her cells instead of 2, causing physical abnormalities, defective sexual development, and infertility.

A boy with 1 or more extra X chromosomes has Klinefelter’s syndrome, which causes defective sexual development and infertility. The presence of an extra X chromosome in women or an extra Y chromosome in men normally has no physical effect but increases the risk of mild mental handicap.

Chromosomal abnormalities are diagnosed by chromosome analysis in early pregnancy, using amniocentesis or chorionic villus sampling.
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Chromium

The Chromium - A metallic element that has a vital role in the activities of several enzymes in the body. Chromium is required only in minute amounts (see trace elements).

In excess, chromium is toxic and produces inflammation of the skin and, if inhaled, damages the nose and may increase the risk of lung cancer.
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Christmas disease

The Christmas disease - A rare genetic bleeding disorder in which there is deficient production of one of the proteins in blood needed for blood coagulation (see blood clotting). Christmas disease has similar features to haemophilia.
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choroid plexus

The choroid plexus - A network of thinwalled blood vessels in the eye or brain. The choroid plexus of the eye supplies blood to the retina. In the brain, the choroid plexus lines the ventricles and produces cerebrospinal fluid.
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Choroiditis

The Choroiditis - Inflammation of the choroid. It is often caused by infections such as toxocariasis or toxoplasmosis, more rarely by sarcoidosis, syphilis, and histoplasmosis.

It sometimes has no obvious cause. Treatment includes corticosteroid drugs for the inflammation, and antibiotic drugs for any causative infection.
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Choroid

The Choroid - A layer of tissue at the back of the eye, behind the retina. The choroid contains many blood vessels that supply nutrients and oxygen to the retinal cells and to surrounding tissues in the eye.
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Chorionic villus sampling

The Chorionic villus sampling - A method of diagnosing genetic abnormalities in a fetus using a small sample of tissue taken from the chorionic villi at edge of the placenta.

Because the cells have the same chromosome makeup as those in the fetus, they can be used to detect genetic abnormalities.

Chorionic villus sampling (CVS) is usually performed in the first 3 months of pregnancy in women who are at a higher-than-normal risk of having a child with a chromosomal disorder, such as Down’s syndrome, or a genetic disease, such as thalassaemia. Chromosome analysis of the villi cells takes place in the laboratory. CVS slightly increases the risk of miscarriage.
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Chorion

The Chorion - One of the 2 membranes that surround the embryo. The chorion lies outside the amnion, has small fingerlike projections called the chorionic villi, and develops into the placenta.

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Choriocarcinoma

The Choriocarcinoma - A rare cancerous tumour that develops from placental tissue in the uterus, usually as a complication of a hydatidiform mole (a noncancerous tumour) but sometimes after a normal pregnancy or a miscarriage.

Untreated, it destroys the walls of the uterus and may spread to the vagina and vulva and, eventually, to the liver, lungs, brain, and bones. Successful treatment relies on early diagnosis.

If a woman has a hydatidiform mole, she is screened regularly after treatment using ultrasound scanning and tests to measure blood and urine levels of the hormone human chorionic gonadotrophin (HCG).

High levels of HCG are associated with choreocarcinoma. Treatment is with anticancer drugs.
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Choreoathetosis

The Choreoathetosis - A condition in which the jerky, uncontrolled movements characteristic of chorea are combined with the slower, continuous writhing movements of athetosis. Choreoathetosis occurs in children with cerebral palsy and as a side effect of certain drugs.
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Chorea

The Chorea - A condition characterized by irregular, rapid, jerky movements, usually affecting the face, limbs, and trunk. It is a feature of Huntington’s disease and Sydenham’s chorea, and may occur in pregnancy.

Chorea may also be a side effect of certain drugs, including oral contraceptives; certain drugs for psychiatric disorders; and drugs for treating Parkinson’s disease.

Symptoms usually disappear when the drug is withdrawn. Underlying causes of chorea are treated with drugs that inhibit nerve pathways concerned with movement.

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Chordee

The Chordee - Abnormal curvature of the penis, usually downwards. Chordee mainly occurs in males with hypospadias, a birth defect in which the urethral opening lies on the underside of the penis. Corrective surgery is usually performed between the ages of 1 and 3 years.
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Chondrosarcoma

The Chondrosarcoma - A cancerous growth of cartilage occurring within or on the surface of large bones, causing pain and swelling.

Usually occurring in middle age, the tumour develops slowly from a noncancerous tumour (see chondroma; dyschondroplasia) or from normal bone. Amputation of the bone above the tumour usually results in a permanent cure.
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Chondromatosis

The Chondromatosis - A condition in which multiple noncancerous tumours, called chondromas, arise in the bones, most commonly the bones of the hands and feet. The tumours consist of cartilage cells and usually cause no symptoms.
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Chondromalacia patellae

The Chondromalacia patellae - A painful disorder of the knee in which the cartilage behind the patella (kneecap) is damaged.

Adolescents are most commonly affected. The condition may result from knee injuries or sporting activities in which the knee is bent for long periods.

This action weakens the inner part of the quadriceps muscle (at the front of the thigh) causing the patella to tilt when the knee is straightened and rub against the lower end of the femur. The cartilage that covers both bones becomes roughened, causing pain and tenderness.

Treatment is with analgesic drugs and exercises to strengthen the thigh muscles. Rarely, surgery may be needed.
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Chondroma

The Chondroma - A noncancerous tumour composed of cartilage, affecting the bones. Chondromas most often occur in the hands and feet (see chondromatosis).
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Chondro

The Chondro- A prefix denoting a relationship to cartilage, as in chondrocyte, a cell that produces cartilage.
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Chondritis

The Chondritis - Inflammation of a cartilage, usually caused by pressure, stress, or injury. Costochondritis is inflammation affecting the cartilage between the ribs and the sternum (breastbone).

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Cholesterol

The Cholesterol - A fat-like substance that is an important constituent of body cells and is also involved in the formation of hormones and bile salts.

Cholesterol in the blood is made by the liver from foods, especially saturated fats, although a small amount is absorbed directly from cholesterol-rich foods such as eggs.

High blood cholesterol levels increase the risk of atherosclerosis, and with it the risk of coronary artery disease or stroke. In general, cholesterol transported in the blood in the form of low-density lipoproteins (LDLs) or very low-density lipoproteins (VLDLs) is a risk factor for these conditions, while cholesterol in
the form of high-density lipoproteins (HDLs) seems to protect against arterial disease.

Blood cholesterol levels are influenced by diet, heredity, and metabolic diseases such as diabetes mellitus, and can be measured by blood tests. Levels below 5.2 mmol/L are acceptable; higher levels may require further tests.

Dietary changes can lower cholesterol slightly; drugs such as simvastatin achieve a greater reduction.
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Cholesteatoma

The Cholesteatoma - A rare but serious condition in which skin cells proliferate andgrow inwards from the ear canal into the middle ear.

Cholesteatoma usually occurs as a result of long-standing otitis media together with a defect in the eardrum (see eardrum, perforated). Left untreated, it may damage the small bones in the middle ear and other structures.

Cholesteatoma needs to be removed surgically through the eardrum or by mastoidectomy.

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Cholestasis

The Cholestasis - Stagnation of bile in the small bile ducts within the liver, leading to jaundice and liver disease. The obstruction to the flow of bile may be intrahepatic (within the liver) or extrahepatic (in the bile ducts outside the liver).

Intrahepatic cholestasis may occur as a result of viral hepatitis (see hepatitis, viral) or as a side effect of a number of drugs. The flow of bile improves gradually as the inflammation from the hepatitis resolves or the drug is discontinued.

The bile ducts outside the liver can become obstructed by, for example, gallstones or tumours (see bile duct obstruction); rarely, the ducts are absent from birth (see biliary atresia). Bile duct obstruction and biliary atresia are often treated surgically.
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Cholera

The Cholera - An infection of the small intestine by the bacterium VIBRIO CHOLERAE causing profuse watery diarrhoea, which can lead to dehydration and death.

Infection is acquired by ingesting contaminated food or water. Outbreaks of cholera occur regularly in northeast India, but worldwide the disease is controlled by sanitation.

Treatment is with water containing salts and sugar (see oral rehydration therapy) and, in severe cases, intravenous infusion. Antibiotic drugs can shorten the period of diarrhoea and infectiousness.

With adequate rehydration, affected people usually make a full recovery from the infection.

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Cholecystokinin

The Cholecystokinin - A gastrointestinal hormone produced in the duodenum in response to the ingestion of fats and other food substances.

It stimulates the release of bile from the gallbladder and digestive enzymes from the pancreas, thus facilitating the digestive process.
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Cholecystography

The Cholecystography - An X-ray procedure that uses a contrast medium to examine the gallbladder and common bile duct, usually to detect gallstones. Cholecystography has largely been replaced by ultrasound scanning of the gallbladder.
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Cholecystitis

The Cholecystitis - Acute or chronic inflammation of the gallbladder, causing severe abdominal pain. Acute cholecystitis is usually caused by a gallstone obstructing the outlet from the gallbladder.

The trapped bile causes irritation of the gallbladder walls and may become infected by bacteria. The main symptom is severe constant pain in the right side of the abdomen under the ribs, accompanied by fever and, occasionally, jaundice.

Treatment is usually with analgesic drugs, antibiotic drugs, and an intravenous infusion of nutrients and fluids. In some cases, complications develop, which may include peritonitis, if the gallbladder bursts, and empyema.

Both require urgent surgical treatment. Repeated mild attacks of acute cholecystitis can lead to a chronic form, in which the gallbladder shrinks, its walls thicken, and it ceases to store bile.

Symptoms (indigestion, pains in the upper abdomen, nausea, and belching) may be aggravated by eating fatty food. Cholecystectomy is the usual treatment.
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Cholecystectomy

The Cholecystectomy - Surgery to remove the gallbladder, usually to deal with gallstones. Cholecystectomy is also used in acute cholecystitis and as an emergency treatment for perforation of the gallbladder or empyema.

The procedure is carried out using conventional surgery or, more commonly, by minimally invasive surgery using a laparoscope.
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Cholangitis

The Cholangitis - Inflammation of the common bile duct (see biliary system). There are 2 types: acute ascending cholangitis and sclerosing cholangitis. Acute ascending cholangitis is usually due to bacterial infection of the duct and its bile, generally as a result of blockage of the duct by, for example, a gallstone (see bile duct obstruction).

The infection spreads up the duct and may affect the liver. The main symptoms are recurrent bouts of jaundice, abdominal pain, chills, and fever. Mild attacks are treated with antibiotics and a high intake of fluids.

In severe, life-threatening attacks, which may be accompanied by septicaemia and kidney failure, the infected material may be drained from the bile duct by surgery or endoscopy.

Sclerosing cholangitis is a rare condition in which all the bile ducts within and outside the liver become narrowed. The condition causes cholestasis, chronic jaundice, and itching of the skin.

The liver is progressively damaged. Colestyramine may relieve itching. The only other treatment available is a liver transplant.
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Cholangiography

The Cholangiography - A procedure that uses a contrast medium to make bile ducts visible on X-rays. Cholangiography is used to look for biliary stones or to diagnose narrowing or tumours of the bile ducts.
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Cholangiocarcinoma

The Cholangiocarcinoma - A cancerous growth in one of the bile ducts, which causes jaundice and weight loss.
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Choking

The Choking - Partial or complete inability to breathe due to an obstruction of the airways. Choking is often due to food or drink entering the trachea and bronchi instead of passing from the pharynx into the oesophagus. Coughing normally dislodges the food or drink.

An obstruction that partially blocks the airway and cannot be dislodged by coughing is more serious. If the airway is completely blocked, total suffocation will result if the blockage is not removed.

If an obstruction cannot be cleared by first aid techniques, such as the Heimlich manoeuvre or removed manually, an emergency tracheostomy may be performed to restore
the airway before removal of the obstruction with instruments.
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