Eczema: Conquering the Itch-Scratch Cycle in Atopic Dermatitis
Itching in multiple areas of the skin at the same time can drive patients and parents nuts. Eczema is a skin condition (dermatitis) that can occur in children and adults but often starts at a very young age. Males and females are almost equally affected, with the condition marked by a cycle of itching and scratching associated with reddening, weeping and oozing of the skin. Scarring and discoloration of the skin may occur after weeks to months of the itch-scratch cycle.
The chief complaint of older children and adults is of the constant, intense itching. Young children who are not yet able to verbalize their complaints sadly suffer through days and nights of what seems like habitual rubbing and scratching, often to the point of bleeding.
There are two major subtypes of eczema, atopic (allergic) and non-allergic. Atopic Dermatitis (AD) also referred to as allergic eczema, is the more common form of eczema that usually begins well before school age. In fact more than 60 percent of the time AD is diagnosed in the first year of life. Other terms used for this chronic dermatitis include hereditary eczema and atopic eczema. In developed countries somewhere between 10-20 percent of children and 1-3 percent of adults have AD.
How is atopic dermatitis diagnosed?
Atopic dermatitis is generally diagnosed by history and physical exam. Historical factors that include a family history of eczema or other allergic conditions may support the diagnosis. Visual appearance of the rash including pattern and distribution (how it looks and where it is located on the body) is crucial to the diagnosis. Skin biopsy is rarely needed since the rash has a fairly unique appearance and natural course. There is almost always a history of severe itching and scratching. The identification of allergic triggers (certain foods or environmental allergy triggers) through skin tests or blood tests further establishes the diagnosis.
What causes atopic dermatitis?
The cause of AD is not quite clear but much has been learned about the processes involved with it. There are three main factors associated with the emergence and progression of AD:
First, the skin loses its ability to prevent water loss. In other words, the skin is leaky, resulting in it drying out over time. Dry skin tends to be much itchier than adequately moisturized skin. In 2007 a gene responsible for normal skin barrier function was discovered to be abnormal in patients with AD. This gene is called filaggrin and has been intensively studied. Other genes that play a different role are currently under investigation.
Second, AD is associated with increased skin inflammation highlighted by the infiltration of various white blood cell types that release substances which promote further inflammation. Some of these substances have been identified and may be the target of future therapeutic agents. Allergic triggers may trigger this inflammatory process. The most common food triggers are in a group called the "Big Eight". They account for more than 90 percent of the food allergy triggers in AD. These include: milk, egg, wheat, soy, fin fish, shell fish, peanut and tree nut. Environmental factors may occasionally trigger AD and include dust mite, pollen and furred pets.
Third, the skin of patients who have AD is more susceptible to infection by certain bacterial and viral organisms which include staphylococcus, herpes and molluscum. Skin inflammation may be greatly intensified by infection from these and similar microbial organisms.
How is Atopic Dermatitis Treated?
Current treatment plans address the above three characteristics with three main goals:
Elimination of itching and scratching;
reduction and control skin inflammation; and
prevention of flare-ups, by:
- Aggressive skin moisturizing is crucial to managing AD. Finding an emollient which is well tolerated (doesn't burn) may be a challenge in itself. Your doctor may suggest certain over the counter formulas that have been more helpful in this setting.
- Avoiding certain foods and environmental allergy and irritant triggers may be critical to gaining control of AD. Allergy skin testing or blood test to identify food and environmental triggers is important in order to know what to avoid. Sometimes the elimination of one or two foods can make a world of difference in young children who have milk, egg or wheat allergy. Rarely, environmental triggers (cat, dog, dust mites) may play an important role in this disorder.
- Medications to reduce inflammation and itching include topical steroids and antihistamines respectively. Your doctor should provide guidelines which address how to acutely manage flare-ups and maintain control of inflammation in between them.
Successful management of atopic dermatitis requires a partnership with the patient, doctor and family. Treatment usually involves several life-style changes and home procedures that may early on seem fruitless. Learning as much as you can about the disease and new developments in treatment, may assist your doctor in helping you or your child. My next posting will elaborate on some of the latest approaches to treating atopic dermatitis.
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