Among the endocrine functions those of the thyroid gland have perhaps the greatest influence on mental condition: either insufficiency (hypothyroidism) or excess (hyperthroidism) of thyroid secretion may give rise to mental disturbances.Hypothyroidism.-Two types are distinguished: the one occurring in infancy or early childhood, spoken of as cretinism; and the other occurring in later life, spoken of as myxedema.Cases of goiter, cretinism, and combinations of both have been observed and reported, particularly in goiter regions, for more than 150 years. According to Harington x the essential relationship between goiter and cretinism was first noted by Fodere in 1800.-In 1874 Gull reported a "cretinoid state supervening in adult life in women." 2 -In 1883 Kocher and Reverdin, on the basis of results observed following surgical extirpations of enlarged thyroid glands, definitely connected the symptoms of myxedema with loss of thyroid function. 3 Cretinism is characterized by a stunting of physical and mental development. The stature is below normal; the face is pale, puffed, or marked precociously with wrinkles; the skin is dry; the hair is scant and thin; the mucous membranes are pale and thickened; the teeth are abnormal in shape and implantation and subject to caries; puberty is retarded or even absent, and the cretin may remain infantile through life. Intelligence is below normal and may be on the level of idiocy. (Fig. 42.) This condition may be associated with congenital absence of the thyroid gland, or atrophy, or a fibrous or cystic goiter.Myxedema (Gull's disease), too, is characterized by puffiness and thickening of the skin, which, in contrast with simple edema, does not show pitting on pressure; the skin is also dry, extremities cold, hair atrophied, pulse slow; menstruation is scant. Often there is obstinate constipation. Mentally the patients are dull, slow, apathetic.Etiology.-Cretinism occurs sporadically anywhere, but rarely. It is, however, endemic in certain regions, and there it is common: some 452 x i_« i. • i_ c jj.L in^v/ J. Atsr*, m S s > etc -Height 4 feet. rate which is here found to be 10% to 40% Weight 73 pounds (photo . or more below normal. graph kindly furnished by Both cretinism and myxedema are rare Dr. James Houloose, Los diseases; but there are mild forms of hypo-Angeles County Farm.) thyroidism, which are much more common, are characterized by incomplete syndromes, and present much greater diagnostic difficulties. In many cases the final diagnostic criterion is derived from the therapeutic test. According to H. Zondek 4 vari-lepliform Seizures: Treatment.