CRETINISM, the term given to a chronic disease, either sporadic or endemic, arising in early childhood, and due to absence or deficiency of the normal secretion of the thyroid gland. It is characterized by imperfect development both of mind and body.
The endemic form of cretinism prevails in the valleys of central Switzerland, Tirol and the Pyrenees. In Great Britain cretins have been found in many places but particularly in Derby shire. The disease is not confined to Europe, but occurs in North and South America, Australia, Africa and Asia. Wherever endemic goitre is present, endemic cretinism is present also, and it has been constantly observed that when a new family moves into a goitrous district, goitre appears in the first generation, cretinism in the second. The causation of goitre has now been shown to be due to drinking certain waters, though the particular impurity• in the water which gives rise to this condition has not been deter mined (see GOITRE) . The causation of the sporadic form of "cretinism is obscure. In goitre and cretinism, however, there is deficiency of iodine in the thyroid tissue.
Cretinism is usually unrecognized until the child reaches some 18 months or two years, when its lack of mental development and uncouth bodily form attracts attention. Occasionally the con dition develops later, any time up to puberty. The essential point in the morbid anatomy of cretinism is abnormality of the thyroid gland (see METABOLIC DISEASES). It may be congenitally absent, atrophied, or the seat of a goitre, though this last condition is very rare in cases of sporadic cretinism. The skeleton shows arrested growth, most marked in the case of the long bones. The skull in the endemic form is usually brachycephalic, but in spo radic cases it is more commonly dolichocephalic. When fully grown the cretin's height rarely exceeds 4ft., and is often less than 3 f t. The skin feels doughy from thickening of the subcutane ous tissues, and it hangs in folds over the abdomen and the bends of the joints. Very frequently there is an umbilical hernia. The hair is sparse and coarse and is usually absent on the body of an adult cretin. The temperature is subnormal, and the exposed parts tend to become blue in cold weather. The blood often contains less than half the normal amount of haemoglobin. The mental capacity varies within narrow limits; an intelligent adult cretin may reach the intellectual development of a child of from three to four years of age, though more often the standard attained is even below this. The child cretin learns neither to walk nor talk at the usual time. Often it is unable even to sit without sup port. Some years later a certain power of movement is acquired, but the gait is waddling and clumsy. Speech is long delayed, or in bad cases may be almost entirely lacking. The voice is usually harsh and unpleasant. Of the senses smell and taste are but slightly developed, more or less deafness is generally present, and only the sight is fairly normal. In the adult the genital organs remain undeveloped. If the cretin is untreated he rarely has a long life, 3o years being an exceptional age. Death results from some intercurrent disease.
Cretinism differs clinically from the state of a Mongolian idiot, in whom there is no thickening of the subcutaneous tissues, and much greater alertness of mind; from achondroplasia, in which condition there is usually no mental impairment ; and from infantilism, which covers a group of symptoms whose only com mon point is that the primary and secondary sexual character istics fail to appear at the proper time.
Before 1891 there was no treatment for this disease. The patients lived in hopeless imbecility until their death. But in that year Dr. George Murray published his discovery of the effect of hypodermic injections of thyroid gland extract in cases of myxoe dema (q.v.) a disease manifestly related to cretinism. In the following years Drs. Hector Mackenzie, E. L. Fox of Plymouth, and Howitz of Copenhagen, each working independently, showed the equally potent effect of the gland administered by the mouth. The remedy was soon after applied to cretinism. It has to be used, however, with care and discrimination, since personal idio syncrasy seems to be a very variable factor. Even small doses, if beyond the patient's power, may produce fever, excitement, headache, insomnia and vomiting. The administration must be persisted in throughout life, otherwise myxoedematous symptoms appear. The first most apparent result is growth. Once started, 4 to 6in. may be gained in stature in the first year's treatment, but is usually in inverse ratio to the age of the patient, and also diminishes in later stages of treatment. Mackenzie recorded the case of a cretin aged II years in 1893, when thyroid treatment was started. He grew very rapidly and became a normal child, passed through school, and in 1908 was at one of the universities.