Iferedity seems to bear some influence II, the production of myxcedema. Cases .n %%In :-ymptoms distinctly sugg-ested exi;tence of myx(edema in parents been reported by Taylor and Bidet lard. Parental alcoholism, neuroses, :illicreulosis. cancer, arthritism or its nianifestations, asthma, rheumatism, f-tc.. have been found to an unusual ex tent in the history of the eases reported.
There is strong evidence that myx reden• a. sporadic and endemic cretinism, eaeTexia strumipriva, and the operative n yxcedema of animals are severally species of one genus, and that the one pathological factor common to all these conditions is the occurrence of morbid processes or of operations involving the annihilation of the function of the thy roid body. Ord (Report of a Committee of the Clinical Soc. of London on Myx (edema, '89).
In at least 10 per cent. of the cases collected that occurred in men several seemed to he hereditary. A certain num ber Were preceded by hypertrophy of the thyroid, which disappeared later. Ord (Med. Record, Sept. 13, '90).
Case of myxcedema coming on after long-continued use of iodide of potassimn for another affection. Such a sequence is interesting, considering the supposed virtue of iodine in some form in thy roid enlargement. 11. Stalker (Lan cet, Jan. 10, '91).
Case of myxcedema in a man, aged 36 years, in whom the administration of potas.sium iodide, 10 grains, to relieve some sacral pain, caused dangerous symptoms. The lymphatic glands of the neck were swelled, the eyelids were (edematous, and the patient complained of a sensation of impending dissolution. The symptoms subsided in two days. Potassium iodide might possibly have accelerated the prog-,ress of an incipient myxnedema. Connal (Glasgow Med. Jonr., Oct., '98).
Case of myxcedema whose mother had sufTered during twenty-three years from a malady resembling the patient's. A sister is similarly afflicted, and a brOther, IlOW dead, had a like trouble. E. H. Small Died. Review, Oct. 14, '99).
Violent emotions and sorrow have been adduced as prolific etiological fac tors by Pel.
Pathogenesis.—Complete removal of the thyroid gland, as previously stated (see ANIMAL EXTRACTS, volume i), is fol lowed by symptoms similar to those ob
.
served in myxcedenaa: a fact first re cord.ed by J. L. Reverdin, of Geneva. On the other hand, the internal administra tion of thyroid extract, as is well known, promptly causes the symptoms of this disease to disappear. That myxcedema, therefore, is due to suppression or im pairment of the functions of the gland seems obvious.
With very rare exceptions there is dis coverable a well-marked atrophy of the thyroid. About this all pathologists are agreed. I can find 110 example of autop sies upon cases diagnosed clinically as myxcederna in which the gland was found normal or but little affected. J. George Adami (Trans. Congress Amer. Phys. and Surgs., May 4-6, '97).
Myxcedema in common with sporadic cretinism of children and cachexia , strumipriva is dependent on a loss of function of the thyroid gland. Ord (1Irit. MM. Jour., Nov. 12, '98).
Such being the case, the etiological factors enumerated should in reality be considered in the light of agencies pable of inducing morbid changes in the gland itself, which changes constitute the primary subjective feature of each case.
111yxcedema thus becomes a complex resulting from impairment of the functions of the thyroid gland through local disease.
[This is the only conclusion warranted by our present knowledge, all other con ceptions of the pathogenesis of the dis ease failing in one direction or another.
A few of the theories advanced, how ever, satisfied many of the obscure feat ures of the disease. Hadden based on the diminution of the urea ratio and the hypothermia the theory that the vaso motor system was mainly at fault. This view WaS sustained by Morvan, who at tributed the paralysis and (edema mainly to the influence of cold and damp, a neuroparalysis being the primary mor bid condition. Prolonged lymphatic an giospasin was supposed by Hxdden to prevent the return of various elements into the circulation. Connective-tissue changes, reduction of the urea and uric aeid elimination thus becatne a normal result, with nervous manifestations and hypothermia 3S attendant symptoms and atrophy of the thyroid as one of the main sequels.