In psychiatry, a method for treating phobias used in BEHAVIOUR THERAPY. The affected individual is slowly acclimatised to the cause of his or her fear. (See also ALLERGY.)
A severe or life-threatening reaction is often termed ANAPHYLAXIS. Many immune mechanisms also contribute to allergic disorders; however, adverse reactions to drugs, diagnostic materials and other substances often do not involve recognised immunological mechanisms and the term ‘hypersensitivity’ is preferable. (See also IMMUNITY.)
Adverse reactions may manifest themselves as URTICARIA, wheezing or di?culty in breathing owing to spasm of the BRONCHIOLES, swollen joints, nausea, vomiting and headaches. Severe allergic reactions may cause a person to go into SHOCK. Although symptoms of an allergic reaction can usually be controlled, treatment of the underlying conditon is more problematic: hence, the best current approach is for susceptible individuals to ?nd out what it is they are allergic to and avoid those agents. For some people, such as those sensitive to insect venom, IMMUNOTHERAPY or desensitisation is often e?ective. If avoidance measures are unsuccessful and desensitisation ine?ective, the in?ammatory reactions can be controlled with CORTICOSTEROIDS, while the troublesome symptoms can be treated with ANTIHISTAMINE DRUGS and SYMPATHOMIMETICS. All three types of drugs may be needed to treat severe allergic reactions.
One interesting hypothesis is that reduced exposure to infective agents, such as bacteria, in infancy may provoke the development of allergy in later life.
Predicted developments in tackling allergic disorders, according to Professor Stephen Holgate writing in the British Medical Journal (22 January 2000) include:
Identi?cation of the principal environmental factors underlying the increase in incidence, to enable preventive measures to be planned.
Safe and e?ective immunotherapy to prevent and reverse allergic disease.
Treatments that target the protein reactions activated by antigens.
Identi?cation of how IgE is produced in the body, and thus of possible ways to inhibit this process.
Identi?cation of genes affecting people’s susceptibility to allergic disease.... allergy
The mainstays of treatment are ANTIHISTAMINE DRUGS, taken by mouth, and the use of steroid and cromoglycate nasal sprays and eye drops. Occasionally desensitisation by injection may work if the particular allergen is known.... hay fever
Cause Asthma runs in families, so that parents with asthma have a strong risk of having children with asthma, or with other atopic (see ATOPY) illnesses such as HAY FEVER or eczema (see DERMATITIS). There is therefore a great deal of interest in the genetic basis of the condition. Several GENES seem to be associated with the condition of atopy, in which subjects have a predisposition to form ANTIBODIES of the IgE class against allergens (see ALLERGEN) they encounter – especially inhaled allergens.
The allergic response in the lining of the airway leads to an in?ammatory reaction. Many cells are involved in this in?ammatory process, including lymphocytes, eosinophils, neutrophils and mast cells. The cells are attracted and controlled by a complex system of in?ammatory mediators. The in?amed airway-wall produced in this process is then sensitive to further allergic stimuli or to non-speci?c challenges such as dust, smoke or drying from the increased respiration during exercise. Recognition of this in?ammation has concentrated attention on anti-in?ammatory aspects of treatment.
Continued in?ammation with poor control of asthma can result in permanent damage to the airway-wall such that reversibility is reduced and airway-narrowing becomes permanent. Appropriate anti-in?ammatory therapy may help to prevent this damage.
Many allergens can be important triggers of asthma. House-dust mite, grass pollen and animal dander are the commonest problems. Occupational factors such as grain dusts, hard-metals fumes and chemicals in the plastic and paint industry are important in some adults. Viral infections are another common trigger, especially in young children.
The prevalence of asthma appears to be on the increase in most countries. Several factors have been linked to this increase; most important may be the vulnerability of the immature immune system (see IMMUNITY) in infants. High exposure to allergens such as house-dust mite early in life may prime the immune system, while reduced exposure to common viral infections may delay the maturation of the immune system. In addition, maternal smoking in pregnancy and infancy increases the risk.
Clinical course The major symptoms of asthma are breathlessness and cough. Occasionally cough may be the only symptom, especially in children, where night-time cough may be mistaken for recurrent infection and treated inappropriately with antibiotics.
The onset of asthma is usually in childhood, but it may begin at any age. In childhood, boys are affected more often than girls but by adulthood the sex incidence is equal. Children who have mild asthma are more likely to grow out of the condition as they go through their teenaged years, although symptoms may recur later.
The degree of airway-narrowing, and its change with time and treatment, can be monitored by measuring the peak expiratory ?ow with a simple monitor at home – a peak-?ow meter. The typical pattern shows the peak ?ow to be lowest in the early morning and this ‘morning dipping’ is often associated with disturbance of sleep.
Acute exacerbations of asthma may be provoked by infections or allergic stimuli. If they do not respond quickly and fully to medication, expert help should be sought urgently since oxygen and higher doses of drugs will be necessary to control the attack. In a severe attack the breathing rate and the pulse rate rise and the chest sounds wheezy. The peak-?ow rate of air into the lungs falls. Patients may be unable to talk in full sentences without catching their breath, and the reduced oxygen in the blood in very severe attacks may produce the blue colour of CYANOSIS in the lips and tongue. Such acute attacks can be very frightening for the patient and family.
Some cases of chronic asthma are included in the internationally agreed description CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) – a chronic, slowly progressive disorder characterised by obstruction of the air?ow persisting over several months.
Treatment The ?rst important consideration in the treatment of asthma is avoidance of precipitating factors. When this is a speci?c animal or occupational exposure, this may be possible; it is however more di?cult for house-dust mite or pollens. Exercise-induced asthma should be treated adequately rather than avoiding exercise.
Desensitisation injections using small quantities of speci?c allergens are used widely in some countries, but rarely in the UK as they are considered to have limited value since most asthma is precipitated by many stimuli and controlled adequately with simple treatment.
There are two groups of main drugs for the treatment of asthma. The ?rst are the bronchodilators which relax the smooth muscle in the wall of the airways, increase their diameter and relieve breathlessness. The most useful agents are the beta adrenergic agonists (see ADRENERGIC RECEPTORS) such as salbutamol and terbutaline. They are best given by inhalation into the airways since this reduces the general side-effects from oral use. These drugs are usually given to reverse airway-narrowing or to prevent its onset on exercise. However, longer-acting inhaled beta agonists such as salmeterol and formoterol or the theophyllines given in tablet form can be used regularly as prevention. The beta agonists can cause TREMOR and PALPITATION in some patients.
The second group of drugs are the antiin?ammatory agents that act to reduce in?ammation of the airway. The main agents in this group are the CORTICOSTEROIDS. They must be taken regularly, even when symptoms are absent. Given by inhalation they have few side-effects. In acute attacks, short courses of oral steroids are used; in very severe disease regular oral steroids may be needed. Other drugs have a role in suppressing in?ammation: sodium cromoglycate has been available for some years and is generally less e?ective than inhaled steroids. Newer agents directed at speci?c steps in the in?ammatory pathway, such as leukotriene receptor-antagonists, are alternative agents.
Treatment guidelines have been produced by various national and international bodies, such as the British Thoracic Society. Most have set out treatment in steps according to severity, with objectives for asthma control based on symptoms and peak ?ow. Patients should have a management plan that sets out their regular treatment and their appropriate response to changes in their condition.
Advice and support for research into asthma is provided by the National Asthma Campaign.
See www.brit-thoracic.org.uk
Prognosis Asthma is diagnosed in 15–20 per cent of all pre-school children in the developed world. Yet by the age of 15 it is estimated that fewer than 5 per cent still have symptoms. A study in 2003 reported on a follow-up of persons born in 1972–3 who developed asthma and still had problems at the age of nine. By the time these persons were aged 26, 27 per cent were still having problems; around half of that number had never been free from the illness and the other half had apparently lost it for a few years but it had returned.... asthma
Acute in?ammation is generally the result of a viral infection (see COLD, COMMON) affecting the mucous membrane and paranasal sinuses (see SINUSITIS); less commonly it results from the inhalation of irritant gases. Boils may develop just inside the entrance to the nose, causing pain; these are potentially troublesome as infection can spread to the sinuses. HAY FEVER is one distressing form of acute rhinitis.
Malformations are of various kinds. Racial and familial variations in the external nose occur and may be a reason for RHINOPLASTY. Di?erences in the size and shape of the nose occur, often forming the starting point for chronic in?ammation of the nose, perennial rhinitis (all the year round), hay fever, or ASTHMA. More commonly, obstruction results from nasal polyps or adenoids, leading to inhalation through the mouth. Adenoids are an overgrowth of glandular tissue at the back of the throat, into which the nose opens. Polyps are growths of soft jelly-like character: they arise from chronic in?ammation associated with allergic rhinitis, chronic sinusitis, asthma, and aspirin abuse. Large polyps can cause erosion of the nasal bones and should be surgically removed.
Bleeding (see HAEMORRHAGE).
Foreign bodies At ?rst these may not cause any symptoms, but in time they can cause obstruction of the affected nostril with a foul-smelling bloody discharge. The problem is common with small children who tend to push small objects into their noses. Foreign bodies require removal, sometimes in hospital. Anyone attempting to remove a foreign body should take care not to push it further into the nose.
Loss of sense of smell, or anosmia, may be temporary or permanent. Temporary anosmia is caused by conditions of the nose which are reversible, whereas permanent
anosmia is caused by conditions which destroy the OLFACTORY NERVES. Temporary conditions are those such as the common cold, or other in?ammatory conditions of the nasal mucosa or the presence of nasal polyps (see above). Permanent anosmia may follow in?uenzal NEURITIS or it may also follow injuries to the brain and fractures of the skull involving the olfactory nerves.
Injury to nose The commonest injury is a fracture of the nasal bones or displacement of the cartilage that forms the bridge of the nose. The nasal SEPTUM may also be displaced sideways by a lateral blow. Sporting activities, especially boxing and rugby football, are commonly a cause of nasal injury. If a fracture is suspected, or if there is substantial tissue swelling, an X-ray examination is necessary. Resetting a damaged bone should be done either immediately, before swelling makes surgery di?cult, or ten days or so later when the swelling has subsided. Results are usually good, ensuring a clear airway as well as a restored pro?le. It is not unusual for the cheek-bone to sustain a depressed fracture at the same time as the nose is broken. Careful assessment and prompt surgery are called for. (For more information on fractures, see under BONE, DISORDERS OF).
Rhinitis In?ammation of the MUCOUS MEMBRANE lining the nose. Symptoms include nasal discharge and obstruction, sneezing and sometimes pain in the sinuses. There are several types of rhinitis:
•Allergic – due to allergy to dust, pollen or other airborne particles. Also called hay fever, allergic rhinitis causes a runny nose, sneezing and local congestion. It affects up to 10 per cent of the population and is more common in people suffering from other allergic disorders such as asthma or eczema (see DERMATITIS). Skin tests help to identify the causative ALLERGEN which the sufferer can then try to avoid, although in the case of pollen this is di?cult. Decongestant drugs, ANTIHISTAMINE DRUGS, and CORTICOSTEROIDS may help, as can SODIUM CROMOGLYCATE inhaled regularly during the pollen season. A desensitisation course to a particular allergen sometimes provides long-term relief.
Atrophic rhinitis is caused by a deterioration in the nasal mucous membrane as a result of chronic bacterial infection, nasal surgery or AGEING. Symptoms include persistent nasal infection and discharge and loss of sense of smell. ANTIBIOTICS and, in some cases, OESTROGENS alleviate the symptoms.
Hypertrophic rhinitis results from repeated nasal infection, and is characterised by thickened nasal membranes and congestion of the nasal veins. Removal of thickened mucosa may help severe cases.
Vasomotor rhinitis occurs when the mucosa becomes oversensitive to stimuli such as pollutants, temperature changes or certain foods or medicines. It may occur as a result of emotional disturbances and is common in pregnancy.
Viral rhinitis occurs as a result of infection by the common cold virus; treatment is symptomatic. Sinusitis is sometimes a complication.... nose, disorders of
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