Perpetua Health Dictionary

A type of haemolytic ANAEMIA, attacks of which occur within an hour or two of eating broad beans (Vicia fava). It is a hereditary disease due to lack of an essential ENZYME called glucose-6phosphate dehydrogenase, which is necessary for the continued integrity of the red cell. This defect is inherited as a sex-linked dominant trait, and the red cells of patients with this abnormality have a normal life-span until challenged by certain drugs or fava beans when the older cells are rapidly destroyed, resulting in haemolytic anaemia. Fourteen per cent of African-Americans are affected and 60 per cent of Yemenite Jews in Israel. The perpetuation of the gene is due to the greater resistance against MALARIA that it carries. Severe and even fatal HAEMOLYSIS has followed the administration of the antimalarial compounds pamaquine and primaquine in sensitive individuals. These red cells are sensitive not only to fava beans and primaquine but also to sulphonamides, acetanilide, phenacetin, para-aminosalicyclic acid, nitrofurantoin, probenecid and vitamin K analogues.... favism

Lichen, or licheni?cation, is a term used to describe a thickening of chronically in?amed skin to give a tree-bark-like appearance.

Lichen simplex (neurodermatitis) is a form of eczema (see DERMATITIS) perpetuated by constant rubbing of the affected skin. Typically, well-de?ned plaques occur on one or both sides of the nape of the neck, on the ulnar forearm near the elbow, or on the sides of the calves. It is often associated with emotional stress.

Lichen planus is a less common in?ammation of the skin characterised by small, shiny, ?at-topped violaceous papules which may coalesce to form large plaques. Itching can be intense. Typically seen on the ?exor aspects of the wrists, the lower back and on the legs below the knees, it may also affect the mucous membranes of the mouth and lips. The cause is unknown. While in some patients the disorder appears to be nervous or emotional in origin, it can be caused by certain drugs such as CHLOROQUINE. Severe cases may require oral CORTICOSTEROIDS to control the eruption.... lichen

Means high BLOOD PRESSURE (raised pressure of the circulating blood), but since there is a wide range of ‘normal’ blood pressure in the population, a precise level of pressure above which an individual is deemed hypertensive is arbitrary. (A healthy young adult would be expected to have a systolic pressure of around 120 mm Hg and a diastolic of 80 mm Hg, recorded as 120/80.) Hypertension is not a disease as such but a quantitative deviation from the norm. A person with a pressure higher than the average for his or her age group is usually symptomless – although sometimes such people may develop headaches. The identi?cation of people with hypertension is important because it is a signal that they will be more likely to have a STROKE or myocardial infarct (coronary thrombosis or heart attack) than someone whose pressure is in the ‘normal’ range. Preventive steps can then be taken to lessen the likelihood of their developing these potentially life-threatening conditions.

Blood pressure is measured using two values. The systolic pressure – the greater of the two – represents the pressure when blood is pumped from the left VENTRICLE of the heart into the AORTA. The diastolic pressure is the measurement when both ventricles relax between beats. The pressures are measured in millimetres (mm) of mercury (Hg). Despite the grey area between normal and raised blood pressure, the World Health Organisation (WHO) has de?ned hypertension as a blood pressure consistently greater than 160 mm Hg (systolic) and 95 mm Hg (diastolic). Young children have readings well below these, but blood pressure rises with age and a healthy person may well live symptom free with a systolic pressure above the WHO ?gure. A useful working de?nition of hypertension is the ?gure at which the bene?ts of treating the condition outweigh the risks and costs of the treatment.

Between 10 and 20 per cent of the adult population in the UK has hypertension, with more men than women affected. Incidence is highest in the middle-aged and elderly. Because most people with hypertension are symptomless, the condition is often ?rst identi?ed during a routine medical examination, otherwise a diagnosis is usually made when complications occur. Many people’s blood pressure rises when they are anxious or after exercise, so if someone’s pressure is above normal at the ?rst testing, it should be taken again after, say, 10 minutes’ rest, by which time the reading should have settled to the person’s regular level. BP measurements should then be taken on two subsequent occasions. If the pressure is still high, the cause needs to be determined: this is done using a combination of personal and family histories (hypertension can run in families), a physical examination and investigations, including an ECG and blood tests for renal disease.

Over 90 per cent of hypertensive people have no immediately identi?able cause for their condition. They are described as having essential hypertension. In those patients with an identi?able cause, the hypertension is described as secondary. Among the causes of secondary hypertension are:

Lifestyle factors such as smoking, alcohol, stress, excessive dietary salt and obesity.

Diseases of the KIDNEYS.

Pregnancy (ECLAMPSIA).

Various ENDOCRINE disorders – for example, PHAEOCHROMOCYTOMA, CUSHING’S DISEASE, ACROMEGALY, thyrotoxicosis (see under THYROID GLAND, DISEASES OF).

COARCTATION OF THE AORTA.

Drugs – for example, oestrogen-containing oral contraceptives (see under CONTRACEPTION), ANABOLIC STEROIDS, CORTICOSTEROIDS, NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).

Treatment People with severe hypertension may need prompt admission to hospital for urgent investigation and treatment. Those with a mild to moderate rise in blood pressure for which no cause is identi?able should be advised to change their lifestyle: smokers should stop the habit, and those with high alcohol consumption should greatly reduce or stop their drinking. Obese people should reduce their food consumption, especially of animal fats, and take more exercise. Everyone with hypertension should follow a low-salt diet and take regular exercise. Patients should also be taught how to relax, which helps to reduce blood pressure and, if they have a stressful life, working patterns should be modi?ed if possible. If these lifestyle changes do not reduce a person’s blood pressure su?ciently, drugs to achieve this will be needed. A wide range of anti-hypertensive drugs are available on prescription.

A ?rst-line treatment is one of the THIAZIDES, e?ective at a low dosage and especially useful in the elderly. Beta blockers (see BETAADRENOCEPTOR-BLOCKING DRUGS), such as oxprenolol, acebutol or atenolol, are also ?rst-line treatments. ACE inhibitors (see ANGIOTENSIN-CONVERTING ENZYME (ACE) INHIBITORS) and CALCIUM-CHANNEL BLOCKERS can be used if the ?rst-line choices are not e?ective. The drug treatment of hypertension is complex, and sometimes various drugs or combinations of drugs have to be tried to ?nd what regimen is e?ective and suits the patient. Mild to moderate hypertension can usually be treated in general practice, but patients who do not respond or have complications will normally require specialist advice. Patients on anti-hypertensive treatments require regular monitoring, and, as treatment may be necessary for several years, particular attention should be paid to identifying sideeffects. Nevertheless, e?ective treatment of hypertension does enable affected individuals to live longer and more comfortable lives than would otherwise be the case. Older people with moderately raised blood pressure are often able to live with the condition, and treatment with anti-hypertensive drugs may produce symptoms of HYPOTENSION.

In summary, hypertension is a complex disorder, with di?erent patients responding di?erently to treatment. So the condition sometimes requires careful assessment before the most e?ective therapy for a particular individual is identi?ed, and continued monitoring of patients with the disorder is advisable.

Complications Untreated hypertension may eventually result in serious complications. People with high blood pressure have blood vessels with thickened, less ?exible walls, a narrowed LUMEN and convoluted shape. Sometimes arteries become rigid. ANEURYSM may develop and widespread ATHEROMA (fat deposits) is apparent in the arterial linings. Such changes adversely affect the blood supply to body tissues and organs and so damage their functioning. Patients suffer STROKE (haemorrhage from or thrombosis in the arteries of the BRAIN) and heart attacks (coronary thrombosis

– see HEART, DISEASES OF). Those with hypertension may suffer damage to the retina of the EYE and to the OPTIC DISC. Indeed, the diagnosis of hypertension is sometimes made during a routine eye test, when the doctor or optician notices changes in the retinal arteries or optic disc. Kidney function is often affected, with patients excreting protein and excessive salt in their urine. Occasionally someone with persistent hypertension may suffer an acceleration of damage to the blood vessels – a condition described as ‘malignant’ hypertension, and one requiring urgent hospital treatment.

Hypertension is a potentially dangerous disease because it develops into a cycle of self-perpetuating damage. Faulty blood vessels lead to high blood pressure which in turn aggravates the damage in the vessels and thus in the tissues and organs they supply with blood; this further raises the affected individual’s blood pressure and the pathological cycle continues.... hypertension

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage (International Association for the Study of Pain, 1979). Pain is perceived in the cerebral cortex (see BRAIN) and is always subjective. Sometimes sensations that would usually be benign can be perceived as painful – for example, allodynia (extreme tenderness of the skin) or dysaesthesia (unpleasant skin sensations resulting from partial damage to sensory nerve ?bres, as in herpes zoster, or shingles).

Acute pain is caused by internal or external injury or disease. It warns the individual that harm or damage is occurring and stimulates them to take avoiding or protective action. With e?ective treatment of disease or injury and/or the natural healing process, the pain resolves – although some acute pain syndromes may develop into chronic pain (see below). Stimuli which are su?ciently intense potentially to damage tissue will cause the stimulation of speci?c receptors known as NOCICEPTORS. Damage to tissues releases substances which stimulate the nociceptors. On the surface of the body there is a high density of nociceptors, and each area of the body is supplied by nerves from a particular spinal segment or level: this allows the brain to localise the source of the pain accurately. Pain from internal structures and organs is more di?cult to localise and is often felt in some more super?cial structure. For example, irritation of the DIAPHRAGM is often felt as pain in the shoulder, as the nerves from both structures enter the SPINAL CORD at the same level (often the structures have developed from the same parts of the embryo). This is known as referred pain.

The impulses from nociceptors travel along nerves to the spinal cord. Within this there is modulation of the pain ‘messages’ by other incoming sensory modalities, as well as descending input from the brain (Melzack and Walls’ gate-control theory). This involves morphine-like molecules (the ENDORPHINS and ENKEPHALINS) amongst many other pain-transmitting and pain-modulating substances. The modi?ed input then passes up the spinal cord through the thalamus to the cerebral cortex. Thus the amount of pain ‘felt’ may be altered by the emotional state of the individual and by other incoming sensations. Once pain is perceived, then ‘action’ is taken; this involves withdrawal of the area being damaged, vocalisation, AUTONOMIC NERVOUS SYSTEM response and examination of the painful area. Analysis of the event using memory will occur and appropriate action be taken to reduce pain and treat the damage.

Chronic pain may be de?ned in several ways: for example, pain resistant to one month’s treatment, or pain persisting one month beyond the usual course of an acute illness or injury. Some doctors may also arbitrarily choose the ?gure of six months. Chronic pain di?ers from acute pain: the physiological response is di?erent and pain may either be caused by stimuli which do not usually cause the perception of pain, or may arise within nerves or the central nervous system with no apparent external stimulation. It seldom has a physiological protective function in the way acute pain has. Also, chronic pain may be self-perpetuating: if individuals gain a psychological advantage from having pain, they may continue to do so (e.g. gaining attention from family or health professionals, etc.). The nervous system itself alters when pain is long-standing in such a way that it becomes more sensitive to painful inputs and tends to perpetuate the pain.

Treatment The treatment of pain depends upon its nature and cause. Acute pain is generally treated by curing the underlying complaint and prescribing ANALGESICS or using local anaesthetic techniques (see ANAESTHESIA – Local anaesthetics). Many hospitals now have acute pain teams for the management of postoperative and other types of acute pain; chronic pain is often treated in pain clinics. Those involved may include doctors (in Britain, usually anaesthetists), nurses, psychologists and psychiatrists, physiotherapists and complementary therapists. Patients are usually referred from other hospital specialists (although some may be referred by GPs). They will usually have been given a diagnosis and exhausted the medical and surgical treatment of their underlying condition.

All the usual analgesics may be employed, and opioids are often used in the terminal treatment of cancer pain.

ANTICONVULSANTS and ANTIDEPRESSANT DRUGS are also used because they alter the transmission of pain within the central nervous system and may actually treat the chronic pain syndrome.

Many local anaesthetic techniques are used. Myofascial pain – pain affecting muscles and connective tissues – is treated by the injection of local anaesthetic into tender spots, and nerves may be blocked either as a diagnostic procedure or by way of treatment. Epidural anaesthetic injections are also used in the same way, and all these treatments may be repeated at intervals over many months in an attempt to cure or at least reduce the pain. For intractable pain, nerves are sometimes destroyed using injections of alcohol or PHENOL or by applying CRYOTHERAPY or radiofrequency waves. Intractable or terminal pain may be treated by destroying nerves surgically, and, rarely, the pain pathways within the spinal cord are severed by cordotomy (though this is generally only used in terminal care).

ACUPUNCTURE and TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS) are used for a variety of pain syndromes, particularly myofascial or musculoskeletal pain. It is thought that they work by increasing the release of endorphins and enkephalins (see above). It is possible to implant electrodes within the epidural space to stimulate directly the nerves as they traverse this space before passing into the spinal cord.

Physiotherapy is often used, particularly in the treatment of chronic backache, where pain may be reduced by improving posture and strengthening muscles with careful exercises. Relaxation techniques and psychotherapy are also used both to treat chronic pain and to help patients cope better with their disability.

Some types of chronic pain are caused by injury to sympathetic nerves or may be relieved by interrupting conduction in sympathetic nerves. This may be done in several ways. The nerves may be blocked using local anaesthetic or permanently destroyed using alcohol, phenol or by surgery.

Many of these techniques may be used in the management of cancer pain. Opioid drugs are often used by a variety of routes and methods, and management of these patients concentrates on the control of symptoms and on providing a good quality of life.... pain

n. a disorder of the sense of smell in which scents that are inoffensive to most people are objectionable to the sufferer or in which a bad smell seems to be perpetually present. The disorder is usually due to damage to pathways within the brain rather than in the nose or olfactory nerve.... cacosmia