DEFINITION.-- A non contagious,cutaneous affection characterized by well-formed, dry, and whitish scales,without vesiculation or pustulation, accompanied by cracking of the skin, and having a disposition to recur.
The general health is not appreciably affected, there being few if any symptoms beyond slight itching, which is worse at the commencement.
VARIETIES.-- In the common form of psoriasis there are whitish minute spots, made up of dry, silvery-looking scales, heaped together on tawny-red patches of skin about the extensor aspects of the elbow and knee, and other places where the bones are near the surface ( P. Vulgaris); when the spots are larger, they resemble drops of mortar, and are found on the breast, back, and limbs (P. guttata); then the eruption may be more developed, and extend over a larger surface., sometimes covering an entire limb (P. diffusa); when the eruption runs together in a serpentine form, the scales are thin, and quickly reproduced (P. gyrate); when the scales are large, dry, and adherent, and the patches thickened and cracked, a slight discharge may occur, causing scabs-- this is the chronic form (P. inveterate), but none of these are real varieties, only descriptive names.
Psoriasis progresses by an increase in the size and number of the patches, and their extension along the extremities to the trunk. On the other hand, the cure of the disease is marked by diminution of the scales, and more full exposure of the surface beneath, until gradually the eruption disappears, leaving little or no trace of its former existence. It is sometimes, however, a most obstinate disease.
CAUSES.-- Psoriasis occurs in persons apparently in good health, but who are probably suffering from some form of defective nutrition, as too growth, bad-living, over-study, anxiety, prolonged lactation, etc.,especially where a disposition,often hereditary, exists. The frequent use of state dried fish, and the want of fresh unboiled vegetables, are probably frequent causes. There is some evidence that constitutions more susceptible to Tubercle are more liable to Psoriasis.
TREATMENT.--Merc., Iod., Ac.-nit.,Iris., Sulph., Lyc., Nux Juglans, Nux Ciner., K.-Hydriod, Petrol, (obstinate cases, scaly patches with deep fissures); Ac.-Carbol., Teuc., Ars.(chronic and inveterate cases). Ars. is an excellent remedy, and may be given for two or three months in gradually increasing doses. Veterinaries give this drug freely to horses, and it causes great improvement in their coats.
ACCESSORY MEANS.-- Local.-- Warm baths; preparations of Glycerine (See Sec. 27), if the skin be much cracked, or occasional poultices if it be very hard. The application of the ointment of the Iodide of Sulphur or an ointment of Liquor Carbonis Detergens, often proves most useful in Psoriasis. It should be preceded by a warm bath. The ointment of Chrysarobin is almost specific in removing Psoriasis, but as with all skin diseases it is very important to treat the case constitutionally as well as locally. Merely to get rid of the external appearance is not necessarily to cure the disease, of which the eruption is a symptom. General.-- Nourishing diet, including frequent small quantities of unboiled vegetables; for growing persons, Cod-liver oil (see Sec. 22), except when stale fish is the cause. Any defects in the functions of digestion and assimilation should, if possible, be corrected. Patients who have been overtaxed in mind or body should have rest and change. The daily habit of bathing or cold sponging should be adopted, and will, to a large extent, prevent relapses. Warm and tepid soft-water baths,with the use of pure soap, at bedtime, softens the scales, and promotes the healthy functions of the skin, Free out-of-door exercise is also most useful, and favours the healthy action of the lungs, and the whole of the digestive organs.