Psoriasis

[ Pathogenesis and Pathophysiology ]

 Psoriasis is a common, chronic, recurrent disease of the skin characterised by rounded circumscribed dry erythematous, scaling patches of various sizes, covered by multi-layer greyish white of silvery white scales which appear repeatedly on the erythema. Similar descriptions of it can be found in some traditional Chinese medicine classics, which term the disease white sore (bai bi), loose skin tinea 9song pi xuan) and dry tinea (gang xuan)

The course of psoriasis is inconsistent, following an irregular chronic course marked by remissions and exacerbations of unpredictable onset and duration. Two of the chief features of psoriasis are its tendency to recur and persist.

Psoriasis occurs with equal frequency in both sexes. The onset of psoriasis is at a mean age of 27 years but the range is wide, from a few months to the 70s. It has been shown that around 1% of the population has psoriasis. There appears to be a genetic predisposition and Caucasians seem to be more affected than other races. It is uncommon in those of Afro-Caribbean origin. American Indians and native Fijians do not have psoriasis.

In Western medicine, the cause of psoriasis is still not clear, although it is believed to be a hereditary skin condition, triggered by infections or psychogenic factors. In traditional Chinese medicine, psoriasis is considered to be due to invasion of pathogenic wind which incubates in the yin and blood, or accumulation and stagnation of qi and blood caused by emotional upset. These transform into heat, wind and heat struggle in the skin. Psoriasis may also be caused by impairment of the Liver and Kidneys, or disharmony between the Penetrating (Chong) and Conception (Ren) vessels between the yin and the Blood or between the ying and yang in the Zangfu.  

[ Diagnosis ]

 The lesions tend to develop on the lateral aspects of the four limbs, and especially on the lateral side of the elbows and knees. They may also concentrate on the body trunk and scalp. The lesions are red or pink papules and plaques with distinctive borders. They are characterized by many layers of dry, silverish scales. If the skin is lightly scraped by a bamboo silver, a pink and semi transparent membrane may be formed. If one keeps on scarping, tiny  spots of blood (petechial hemorrhage) may develop. Lesions may vary in size from dots to coins and may either be circular or geographic in shape. If lesions appear in the scalp they will be dark red in colour and will be covered with grayish white scales from which the hair may grow in bundles. However, the hair will not fall out. If the lesions occur on the fingernails, they will appear as dotted depressions similar to thimbles used to push sewing needles through cloth.

[ Treatment principle : Clear heat, resolve toxins and expel wind ]

In general, the longer the patient has suffered from psoriasis the longer the length of treatment. Generally speaking, the course of treatment for the first and second types will be shorter than the third type. Average courses for the treatment for the different patterns are as follows:

1. Flaming of heat-evil at the qi and blood levels combined: 2-3 months.

2. Blood heat and blood stasis plus generalised symptoms : 3-4 months

3: Noxious heat and blood stasis: 4-6 months

Some patients have to continue treatment for longer, possibly over a year, especially those who have lengthy treatment with Western medicine such as steroids (tablet or creams), as the psoriatic lesions become very stubborn. If after a few weeks of treatment the symptoms start to improve, the patient may need to take the treatment consistently until it has cleared completely.

Stress, overwork, seasonal changes, certain foods and some infections are examples of common reasons for relapse or recurrence of psoriasis. It is necessary to ascertain the trigger(s) for the relapse.

[ Prevention ]

1. Take enough rest, refrain from overworking and avoid too much mental stress. 2. Try not to scratch the affected area. During onset., the affected area should be bathed in hot water or with alkali soap. 3. Refrain from eating the following foodstuffs: seafood such as fish and shrimp, beef, lamb, spicy foods, alcohol and caffeinated drinks such as coffee, tea and coca-cola, as these are likely to induce or intensify psoriasis. 4. Sound nutrition should be maintained. Eat more vegetables and fruit in order to keep the bowel movements regular. 5. Try to trace any triggering factors and thereby reduce relapses.

[ External treatment ]

1. Tibetan skin ointment (Fu Le Gao)

2. Centipede cream