Eczema Explained

Eczema
Diseasesdb:4113
Icd10:-
Omim:603165
Medlineplus:000853
Emedicinesubj:Derm
Emedicinetopic:38
Meshid:D004485

Eczema is a form of dermatitis, or inflammation of the epidermis. The term eczema is broadly applied to a range of persistent skin conditions. These include dryness and recurring skin rashes which are characterized by one or more of these symptoms: redness, skin edema (swelling), itching and dryness, crusting, flaking, blistering, cracking, oozing, or bleeding. Areas of temporary skin discoloration may appear and are sometimes due to healed lesions, although scarring is rare. In contrast to psoriasis, eczema is often likely to be found on the flexor aspect of joints.

Types

The term eczema refers to a set of clinical characteristics. Classification of the underlying diseases has been haphazard and unsystematic, with many synonyms used to describe the same condition. A type of eczema may be described by location (e.g. hand eczema), by specific appearance (eczema craquele or discoid), or by possible cause (varicose eczema). Further adding to the confusion, many sources use the term eczema and the term for the most common type of eczema (atopic eczema) interchangeably.

The European Academy of Allergology and Clinical Immunology (EAACI) published a position paper in 2001 which simplifies the nomenclature of allergy-related diseases including atopic and allergic contact eczemas.[1] Non-allergic eczemas are not affected by this proposal.

The classification below is ordered by incidence frequency.

Types of common eczemas

Less common eczemas

Treatment

There is no known cure for eczema, thus treatments aim to control the symptoms: reduce inflammation and relieve itching.

Medications

Corticosteroids

Dermatitis is often treated by glucocorticoid (a corticosteroid) ointments, creams or lotions.They do not cure eczema, but are highly effective in controlling or suppressing symptoms in most cases.[2] For mild-moderate eczema a weak steroid may be used (e.g. hydrocortisone or desonide), whilst more severe cases require a higher-potency steroid (e.g. clobetasol propionate, fluocinonide). Medium-potency corticosteroids such as clobetasone butyrate (Eumovate), Betamethasone Valerate (Betnovate) or triamcinolone are also available. Generally medical practitioners will prescribe the less potent ones first before trying the more potent ones. In many countries, weak steroids can be purchased 'over the counter' (e.g., hydrocortisone in UK, United States, Germany, Czechia, Australia), while the more potent ones require a prescription.

Side effects

Prolonged use of topical corticosteroids is thought to increase the risk of possible side effects, the most common of which is the skin becoming thin and fragile (atrophy).[3] Because of this, if used on the face or other delicate skin, only a low-strength steroid should be used. Additionally, high-strength steroids used over large areas, or under occlusion, may be significantly absorbed into the body, causing hypothalamic-pituitary-adrenal axis suppression (HPA axis suppression).[4] Finally by their immunosuppressive action they can, if used without antibiotics or antifungal drugs, lead to some skin infections (fungal or bacterial). Care must be taken to avoid the eyes, as topical corticosteroids applied to the eye can cause glaucoma [5] or cataracts.

Because of the risks associated with this type of drug, a steroid of an appropriate strength should be sparingly applied only to control an episode of eczema. Once the desired response has been achieved, it should be discontinued and replaced with emollients as maintenance therapy. Corticosteroids are generally considered safe to use in the short- to medium-term for controlling eczema, with no significant side effects differing from treatment with non-steroidal ointment.[6]

However, recent research has shown that topically applied corticosteroids did not significantly increase the risk of skin thinning, stretch marks or HPA axis suppression (and where such suppression did occur, it was mild and reversible where the corticosteroids were used for limited periods of time). Further, skin conditions are often under-treated because of fears of side effects. This has led some researchers to suggest that the usual dosage instructions should be changed from "Use sparingly" to "Apply enough to cover affected areas," and that specific dosage directions using "fingertip units" or FTU's be provided, along with photos to illustrate FTU's.[7]

Other forms

In severe cases, oral cortisosteroids such as prednisolone or injections such as triamcinolone injections may also be prescribed. While these usually bring about rapid improvements, they should not be taken for any length of time and the eczema often returns to its previous level of severity once the medication is stopped.In the case of triamcinolone injections, a waiting period between treatments may be required.

Immunomodulators

Topical immunomodulators like pimecrolimus (Elidel and Douglan) and tacrolimus (Protopic) were developed after corticosteroid treatments, effectively suppressing the immune system in the affected area, and appear to yield better results in some populations.The U.S. Food and Drug Administration has issued a public health advisory about the possible risk of lymph node or skin cancer from use of these products,[8] but many professional medical organizations disagree with the FDA's findings;

Antibiotics

When the normal protective barrier of the skin is disrupted (dry and cracked), it allows easy entry for bacteria. Scratching by the patient both introduces infection and spreads it from one area to another. Any skin infection further irritates the skin and a rapid deterioration in the condition may ensue; the appropriate antibiotic should be given.

Immunosuppressants

When eczema is severe and does not respond to other forms of treatment, immunosuppressant drugs are sometimes prescribed. These dampen the immune system and can result in dramatic improvements to the patient's eczema. However, immunosuppresants can cause side effects on the body. As such, patients must undergo regular blood tests and be closely monitored by a doctor. In the UK, the most commonly used immunosuppressants for eczema are ciclosporin(Cyclosporine), azathioprine and methotrexate. These drugs were generally designed for other medical conditions but have been found to be effective against eczema.Commonly prescribed as an immunosuppressant in the United States for Eczema is the steroid Prednisone.

Itch relief

Anti-itch drugs, often antihistamine, may reduce the itch during a flare up of eczema, and the reduced scratching in turn reduces damage and irritation to the skin (the Itch cycle).

Capsaicin applied to the skin acts as a counter irritant (see: Gate control theory of nerve signal transmission). Other agents that act on nerve transmissions, like menthol, also have been found to mitigate the body's itch signals, providing some relief. Recent research suggests Naloxone hydrochloride and dibucaine suppress the itch cycle in atopic-dermatitis model mice as well.

Avoiding dry skin

Moisturizing

Eczema can be exacerbated by dryness of the skin. Moisturizing is one of the most important self-care treatments for sufferers of eczema. Keeping the affected area moistened can promote skin healing and relief of symptoms.

Soaps and harsh detergents should not be used on affected skin because they can strip natural skin oils and lead to excessive dryness. Instead, the use of moisturizing body wash, or an emollient like aqueous cream, will maintain natural skin oils and may reduce some of the need to moisturize the skin. Another option is to try bathing using colloidal oatmeal bath treatments. In addition to avoiding soap, other products that may dry the skin such as powders or perfume should also be avoided.

Moistening agents are called 'emollients'. In general, it is best to match thicker ointments to the driest, flakiest skin. Light emollients like aqueous cream may not have any effect on severely dry skin. Some common emollients for the relief of eczema include Oilatum, Balneum, Medi Oil, Diprobase, bath oils and aqueous cream. Sebexol, Epaderm ointment, Exederm and Eucerin lotion or cream may also be helpful with itching. Lotions or creams may be applied directly to the skin after bathing to lock in moisture. Moisturizing gloves (gloves which keep emollients in contact with skin on the hands) can be worn while sleeping. Generally, twice-daily applications of emollients work best. While creams are easy to apply, they are quickly absorbed into the skin, and therefore need frequent reapplication. Ointments, with less water content, stay on the skin for longer and need fewer applications, but they can be greasy and inconvenient. Steroids such as Betnovate may also be mixed in with ointments.

For unbroken skin, direct application of waterproof tape with or without an emollient or prescription ointment can improve moisture levels and skin integrity which allows the skin to heal. This treatment regimen can also help prevent the skin from cracking, as well as put a stop to the itch cycle. The end result is reduced lichenification (the roughening of skin from repeated scratching). Taping works best on skin away from joints.

There is a disagreement whether baths are desirable or a necessary evil. For example Mayo Clinic advises against daily baths to avoid skin drying.[12] . On the other hand, U.S. National Eczema Association claims that "the best way to get water into your skin is to briefly soak in a bath or shower and to moisturize immediately afterwards."[13] .Similarly, The Eczema Society of Canada recommends frequent baths[14] and American Academy of Dermatology claims that bathing can hydrate skin.[15]

Recently, ceramides, which are the major lipid constituent of the stratum corneum, have been used in the treatment of eczema.[16] [17] [18] They are often one of the ingredients of modern moisturizers. These lipids were also successfully produced synthetically in the laboratory.[19]

Eczema and skin cleansers

One of the recommendations is that people suffering from eczema shouldn't use detergents of any kind on their skin unless absolutely necessary. Eczema sufferers can reduce itching by using cleansers only when water is not sufficient to remove dirt from skin.

However, detergents are so ubiquitous in modern environments in items like tissues, and so persistent on surfaces, "safe" soaps are necessary to remove them from the skin in order to control eczema. Although most eczema recommendations use the terms "detergents" and "soaps" interchangeably, and tell eczema sufferers to avoid both, detergents and soaps are not the same and are not equally problematic to eczema sufferers. Detergents, often made from petrochemicals, increase the permeability of skin membranes in a way that soaps and water alone do not. Sodium lauryl sulfate, the most common household detergent, has been shown to amplify the allergenicity of other substances ("increase antigen penetration").[20]

Unfortunately there is no one agreed-upon best kind of skin cleanser for eczema sufferers. Different clinical tests, sponsored by different personal product companies, unsurprisingly tout various brands as the most skin-friendly based on specific properties of various products and different underlying assumptions as to what really determines skin friendliness. The terms "hypoallergenic" and "doctor tested" are not regulated,[21] and no research has been done showing that products labeled "hypoallergenic" are in fact less problematic than any others.

Dermatological recommendations in choosing a soap generally include:

Instructions for using soap:

Environmental measures

While it has been suggested that eczema may sometimes be an allergic reaction to the excrement from house dust mites,[22] with up to 5% of people showing antibodies to the mites,[23] the overall role this plays awaits further corroboration.

Various measures may reduce the amount of mite antigens, in particular swapping carpets for hard surfaces.[24] Effectiveness of vacuum cleaners is dependent upon the characteristics of the carpet pile,[25] but in other studies daily vacuuming did not affect levels of mites.[26] However it is not clear whether such measures actually help patients with eczema. A controlled study suggested that a number of environmental factors such as air exchange rates, relative humidity and room temperature (but not the level of house dust mites) might have an effect on the condition.[27]

Light therapy

Light therapy using ultraviolet light can help control eczema.[28] UVA is mostly used, but UVB and Narrow Band UVB are also used. Ultraviolet light exposure carries its own risks, particularly potential skin cancer from exposure, although there is no conclusive evidence of this.[29]

When light therapy alone is found to be ineffective, the treatment is performed with the application (or ingestion) of a substance called psoralen. This PUVA (Psoralen + UVA) combination therapy is termed photo-chemotherapy. Psoralens make the skin more sensitive to UV light, thus allowing lower doses of UVA to be used. However, the increased sensitivity to UV light also puts the patient at greater risk for skin cancer.[30]

Diet and nutrition

Recent studies provide hints that food allergy may trigger atopic dermatitis. For these people, identifying the allergens could lead to an avoidance diet to help minimize symptoms, although this approach is still in an experimental stage. [31]

Dietary elements that have been reported to trigger eczema include dairy products and coffee (both caffeinated and decaffeinated), soybean products, eggs, nuts, wheat and maize (sweet corn), though food allergies may vary from person to person. In certain individuals eczema is triggered by MSG (monosodium glutamate).

Recently German scientists discovered that a diet rich in Omega-3 may be able to reduce symptoms. [32] Vegetarian sources that are most beneficial are wheatgerm oil and Evening Primrose oil and animal sources include Cod-liver oil, although some individuals may be allergic to seafood.

Alternative therapies

Non-conventional medical approaches include traditional Chinese medicine and Western herbalism. There is a wide variety of treatments, each of which may vary from individual to individual as to efficacy or harm. Chinese medicine is known for successfully and permanently resolving eczema. In Chinese Medicine diagnosis, eczema is often a manifestation of underlying ill health. Treatment works by improving the overall health of the individual, therefore not only resolving the eczema but improving quality of life (energy level, digestion, disease resistance, etc.).[33] A recent study published in the British Journal of Dermatology describes improvements in quality of life and reduced need for topical corticosteroid application[34] . Another British trial was carried out in 47 children with extensive nonexudative atopic eczema, over an eight week treatment period. Active intervention comprised ten different plants traditionally used in Chinese medicine for eczema treatment. Of the 37 children analysed, for erythema scores there was a 51% decrease (95% CI 34.5 to 72.6) with active and a 6.1% decrease (95% CI -25.2 to 30.7) for placebo. For surface damage scores there was a 63.1% decrease (95 CI 34.5 to 72.6) with active and a 6.2% decrease (95% CI -25.2 to 30.7) with placebo. Both scores suggest a benefit with herbal remedy.[35]

It must be emphasized that Traditional Chinese Medicine is a licensed medical profession and must only be prescribed by physicians with proper education and board certification.[36] Patients should inform their doctor/allergist/dermatologist if they are pursuing one of these treatment routes.

Alleged remedies include:

According to the British Association of Dermatologists, there is considerable anecdotal evidence that salt water baths may help some children with atopic eczema. One reason might be that seawater has antiseptic properties. The Dead sea is popular for alleviating skin problems including eczema.

Patients can also wear clothing designed specifically to manage the itching, scratching and peeling associated with eczema.[40]

Behavioural approach

In the 1980s, Swedish dermatologist Peter Noren developed a behavioural approach to the treatment of long term atopic eczema. This approach has been further developed by dermatologist Richard Staughton and psychiatrist Christopher Bridgett at the Chelsea and Westminster Hospital in London.[41] [42] Patients undergo a 6 week monitored program involving scratch habit reversal and self awareness of scratching levels. For long term eczema sufferers, scratching can become habitual. Sometimes scratching becomes a reflex, resulting in scratching without conscious awareness, rather than from the feeling of itchiness itself. The habit reversal program is done in conjunction with the standard applied emollient/corticosteroid treatments so that the skin can heal. It also reduces future scratching, as well as reduces the likelihood of further flareups. The behavioural approach can give an eczema sufferer some control over the degree of severity of eczema.

Home treatments

Dyshidrosis can be treated locally by braking early on the tiny vesicles with a small needle and disinfecting the scratch. It will reverse the eczemic inflammation and begin a scarring process, which stops the vesicle formation and the drying of the skin around the braked vesicle, and temporarily prevents the formation of new vesicles to the same area of the skin. When kept clean properly, the braked vesicles will first turn into scars, after which using dexpanthenol (vitamin B12) ointment heals the cracked and dry area of old vesicles.

Research

Other than direct treatments of the symptoms, no cure is presently known for most types of dermatitis; even cortisone treatments and immunomodulation may often have only minor effects on what may be a complex problem. As the condition is often related to family history of allergies (and thus heredity), it is probable that gene therapy or genetic engineering might help.

Damage from the enzymatic activity of allergens is usually prevented by the body's own protease inhibitors, such as, LEKTI, produced from the gene SPINK5. Mutations in this gene are known to cause Netherton’s syndrome, which is a congenital erythroderma. These patients nearly always develop atopic disease, including hay fever, food allergy, urticaria and asthma. Such evidence supports the hypothesis that skin damage from allergens may be the cause of eczema, and may provide a venue for further treatment. [43]

Another study identified a gene that the researchers believe to be the cause of inherited eczema and some related disorders. The gene produces the protein filaggrin, the lack of which causes dry skin and impaired skin barrier function.[44]

A recent study indicated that two specific chemicals found in the blood are connected to the itching sensations associated with eczema. The chemicals are Brain-derived neurotrophic factor (BDNF) and Substance P.[45]

Vulnerability to live vaccinia virus

In June, 2007, Science magazine reported that an American soldier who had been vaccinated for smallpox, a vaccine that contains live vaccinia virus, had transmitted vaccinia virus to his two-year-old son.[46] The soldier and his son both had a history of eczema. The son rapidly came down with a rare side effect, eczema vaccinatum, which had been seen during the 1960s when children were routinely vaccinated against smallpox. The child developed a severe full-body pustular rash, his abdomen filled with fluid, and his kidneys nearly failed. Intense consultation with experts from the Centers for Disease Control and Prevention and a donation of an experimental antiviral drug by SIGA Technologies saved the child's life. Those with a family history of eczema are advised not to accept the smallpox vaccination, or anything else that contains live vaccinia virus.

External links

Notes and References

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