44 INTERNAL SECRETION 



the mother upon the offspring are very interesting. The young 

 of rats from which the parathyroids had been removed were found 

 to be highly sensitive to electric stimuli, and were so susceptible 

 to parathyroidectomy that four to ten hours after operation they 

 succumbed to tetany in its most violent form. 



TETANY IN MAN. 



Experiments with animals, such as those described above, 

 paved the way for a closer investigation of the part played by 

 the parathyroid glands in the tetany of man. 



There is no doubt that the tetania strumipriva of man, like 

 the tetania thyropriva of animals, is due to injury or removal of 

 the parathyroids when extirpating a goitre. This view was 

 originally propounded by Vassale and Generali and it has been 

 confirmed by many other observers (Biedl, Jeandelize, Pineles). 

 Benjamins showed that one to three parathyroids may be found 

 attached to an extirpated goitre and this sufficiently explains the 

 occurrence of post-operative tetany. Erdheim found that in three 

 cases of tetany following partial excision of a goitre, all four 

 parathyroids had been removed. In a fourth case, one para- 

 thyroid had been left, but it had become necrosed, as the artery 

 below it had been ligatured. 



Whether or not the extirpation of a goitre will be followed 

 by tetany, depends entirely upon the amount of parathyroid tissue 

 left intact and the functional capacity of the tissue thus remaining. 

 The first care of the surgeon who extirpates a goitre should be 

 to spare, wherever possible, all parathyroid glands. It is also 

 essential, as we shall see later, that a sufficient amount of thyroid 

 parenchyma should be left intact. For this reason, methods of 

 intracapsular resection or enucleation are by far the best. Of 

 such are Mikulicz's wedge-resection, and Kocher's resection- 

 enucleation methods. 



In man, as in animals, a post-operative transient tetany, due 

 to mechanical lesions of the parathyroid glands or injury of their 

 blood supply, is sometimes observed. Cases have been described 

 where thyroidectomy has not been followed by any apparent 

 symptom and yet a condition of latent tetany must have existed, 

 for under the influence of certain momenta, such as pregnancy, 

 tetany has appeared. 



A second form of tetany, which we know from the results 

 of both animal and human pathology to owe its origin to the 

 parathyroid glands, is that known as the tetany of maternity, or 

 puerperal tetany. That there is an intimate connection between 

 tetany and the functions of the female organs of generation 

 (menstruation, pregnancy, lactation) has been frequently pointed 

 out by clinicians. 



It has been shown that the partial parathyroidectomy of 



