Occlusive Treatment Of Psoriasis - State Of The Art
A. Sousa Basto
In the 1980s, dermatologist Ronald Shore spoke for the first time the effectiveness of the occlusive method in the treatment of psoriasis (1). The continuous application of an impermeable occlusive film for approximately one week would decrease psoriasis plaques since the first application (2). In some patients two or even three sessions were needed. He also verified that if the plaque was to be hydrated before applying the film the effects would be even more evident. Other authors later described the benefits of the occlusive method after applying topic cortico-steroids in many inflammatory problems, including atopic dermatitis and other chronic eczema states (3).
The occlusive technique was mainly advised for treating isolated plaques as opposed to multiple or extensive lesions due to the amount of time it took to apply the film. This was why it had been a little out of medical practice, until there were suits with the purpose of making this technique more practical and comfortable and that increased patient adhesion to this type of dermatose treatment.
The way in which occlusion acts is not completely clear, so every explanation is merely speculative. However, the increase in sudation creates a state of hyper-hydration of the epidermis that counteracts the uncontrollable growth of keratinocytes, being that this effect is magnified by the application of an emollient or hydrating agent.
There are at least four effects of occlusion that may be relevant to psoriasis. Occlusion reduces the mitotic activity of the skin, interferes with granulous layer restoration, prevents parakeratosis, which is a factor for dehydration, and hyperhydrates the horny layer of the skin, enabling descamative processes. (4)
Sang Min Hwang et al. attribute occlusion benefits to its effect over the lipidic structures of the horny extract, enhancing the altered barrier function, as well as the calcium gradient. (5)
In dermatosis where it is advised the use of drugs the attending doctor should be consulted, for the application of certain active principles can dramatically enhance their transcutaneous absorption and unrecommended levels can be reached.
Recently there have been introduced in the national market occlusive suits that will make it easier to use the occlusive technique in large extensions of the body, enabling the use of emollients, hydrating substances and topical drugs in situations of dry skin and in chronic inflammatory dermatosis, from which psoriasis is an example, avoiding in many cases the prescription of systemic treatments and their potential adverse effects.
(1) Shore RN. Clearing of psoriatic lesions after the aplication of a tape. N Engl J Med 1985;312:246
(2) Shore RN. Treatment of psoriasis with prolonged application of tap. J. Am Acad Dermatol 1986;15:540-541
(3) Volden G. Successful treatment of therapy-resistent atopic dermatitis with clobetasol propionate and a hydrocolloid occlusive dressing. Acta Derm Venereol (Stockh) 1992;176 (suppl):126-128
(4) Griffiths CEM et al. Prolonged occlusion in the treatment of psoriasis: a clinical and immunohistologic study. J Am Acad Dermatol 1995;32:618-622
(5) Sang Min Hwang et al. Basis of occlusive therapy in psoriasis: correcting defects in permeability barrier and calcium gradient. Int J Deramatol 2001;40:223-231