Synonyms.—Sporadic Cretinism; Athyria.
Definition.—A chronic constitutional disorder, due to functional derangement of the thyroid gland, and characterized by infiltration (myxedema) of mucin in the subcutaneous tissues.
Varieties.—Three varieties are given: (a) True myxedema, or adult myxedema; (b) Sporadic cretinism; (c) Operative myxedema, or cachexia strumipriva.
The removal of the thyroid gland in lower animals demonstrates that the myxedema of adults, cretinism, and the cachectic condition following the removal of the thyroid gland for goitre, represent the same morbid condition though under different circumstances.
Etiology.—The secretions from the ductless glands possess various constituents that are necessary to normal metabolism, and when their function is impaired, and these constituents are absent or perverted, disorders of nutrition follow.
The thyroid secretion contains such a constituent, which has been named thyroidin, and when this is absent, myxedema results. More cases have been found in England and Switzerland than from all other countries. Women suffer more frequently than men, the ratio being 6 to 1.
It occurs most frequently between the ages of thirty-five and fifty. Pregnancy seems to predispose to it; at least married women who have borne children suffer more often than the unmarried.
Heredity may play some part as a predisposing factor, and exophthalmic goitre may bear some relation to the disease.
Actinomycosis has been reported as destroying the gland in a reported case of myxedema.
Pathology.—Lesions of the thyroid are constant, there either being atrophy or degeneration. The gland may be congenitally absent, as in cretinism. Occasionally it is larger than normal, the secreting structure being replaced by interstitial fibrous tissue. Myxomatous changes in the blood-vessels and kidneys have been recorded.
Symptoms.—The disease comes on insidiously, the first symptoms appearing in the face, which loses its expression and takes on a coarse or bloated appearance. There is puffiness of the eyes, and the patient is dull and stupid. The tongue is broad, thick, and more or less coated. The nose increases in breadth, becomes flattened, and is inclined to turn up at the end. The lips become thick, the lower sometimes being slightly everted; the ears are enlarged, and the hair becomes coarse and is inclined to drop out. The skin becomes dry and harsh; the teeth decay, and the nails are dry and brittle.
The extremities become large and clumsy, and the hands and feet are swollen and become less flexible, and the body generally increases in bulk. The movements of the patient are slow. The heart's action is feeble, though the pulse may be rapid. The temperature is normal or subnormal. There may be traces of albumin and sugar in the urine.
The mental faculties become dulled, the patient reasoning with difficulty, taking on more and more the appearance of imbecility as the disease progresses.
Headache is often present, and the special senses, smell, taste, sight, hearing, and touch, become impaired.
Diagnosis.—The general swollen or bloated appearance, yet absence of pitting on pressure, the dry, harsh skin, the dull besotted appearance, the clumsy movements, are symptoms not likely to be mistaken for any other lesion.
Prognosis.—The disease is one of marked chronicity, lasting five, ten, or fifteen years. Since the introduction of the thyroid-gland treatment, many favorable reports have been received as to its curative action.
The thyroids of sheep and calves are used, and may be given raw or cooked, or in the form of glycerin extract, or the dry powdered extract.
Ail forms of myxedema seem to respond to this treatment, if reports are to be relied upon. If the gland be destroyed or removed, the treatment is to be continued at intervals during life.