PARATHYROID GLANDS 585 



of the thyroid gland alone causes myxedema without tetany (myxedema 

 operativum chronicum, cachexia strumipriva) . Removal of three or more 

 parathyroid glands alone causes tetany without myxedema (tetania para- 

 thyropriva). Removal of both thyroid gland and parathyroid glands 

 simultaneously causes tetany with myxedema (tetania thyroparathyro- 

 priva; myxedema operativum acutum). Tetany was found to follow 

 experimental parathyroidectomy in dogs, cats, rabbits, rats, mice, goats, 

 monkeys, hens and frogs. Animals with partial parathyroidectomy often 

 remained free from symptoms, but could be shown to be in a condition 

 of latent tetany, and Vassale showed that animals with such latent tetany 

 might exhibit manifest tetany during pregnancy. Practically all of the 

 symptoms observable in acute and chronic tetany in man have been repro- 

 duced in animals by removal of, or injury to, their parathyroid glands. 

 In these experimental contributions a host of investigators have been 

 active (Gley (c)(e), Vassale and Generali (a.) (6), Erdheim, Moussu, 

 Christian!, W. S. Halsted, W. G. MacCallum, Victor Horsley, Laurence 

 Hermann, A. J. Carlson, A. Biedl, and many others). 



Considering the observations made by those who experimented upon 

 animals, there remained but little room for doubt that tetany after stru- 

 mectomy in human beings, too, must be due to removal of, or injury to, 

 the parathyroid glands. This view had been put forward by Jeandelize 

 (1902) and by Biedl, and was strongly supported by the studies of Pineles 

 (6) (1905), Benjamin (1902), and Erdheim (c)(1906). Thus, Pineles 

 showed that in the clinical picture of thyro-aplasia, in which* there is com- 

 plete absence of the thyroid gland, when the parathyroid glands are en- 

 tirely normal, signs of tetany are never present. He argued that this dem- 

 onstrated a, definite connection between tetany and the loss of function of 

 the parathyroid glands. He adduced, further, the observations, (1) that 

 tetany does not follow extirpation of goiter of the lobulus lingualis (Zun- 

 genkropf), whereas (2) tetany relatively often appears when strumectomy 

 is done without removing the isthmus of the thyroid. These two facts also 

 demonstrated the existence of a close connection between the parathyroid 

 glands and the contractures of tetany, for the four parathyroid glands lie 

 behind the lateral lobes of the thyroid and there are no parathyroids behind 

 the isthmus or the lobulus lingualis when the latter is present. Even more 

 conclusive were the observations of Benjamin and of Erdheim. Thus, 

 Benjamin found that from one to three parathyroid glands were sometimes 

 attached to extirpated human goiters, involving a loss of parathyroid 

 function sufficient to explain the postoperative tetany; and Erdheim 

 showed that, in three cases of tetany that followed partial strumectomy, all 

 four parathyroid glands had been removed with the parts of the thyroid 

 that had been taken out. In one instance Erdheim found at autopsy a 

 parathyroid gland that had undergone necrosis as the result of cutting off 

 its blood supply at the operation for goiter. These clinical-pathological 



