586 LEWELLYS F. BAKKEK 



examinations demonstrated, then, beyond any reasonable doubt, that tetany 

 after strumectomy is due to removal of, or injury to, the parathyroid 

 glands, in other words that in tetania strumipriva the human being is in a 

 status parathyroprivus (Halsted (&)) 



The result of all these studies was that the technic of the operation 

 of strumectomy could be rationally revolutionized, so as to avoid injury 

 to, or removal of, the parathyroid glands- and an ensuing tetany. Surgeons 

 learned how to leave the parathyroid glands behind, how to avoid injury 

 to them, and how to preserve their blood supply intact when operating 

 upon goiter. As so often happens in medicine, however, an approach 

 to what afterwards was conducted as a rational procedure had already been 

 sained on empirical grounds by astute and observant surgeons before the 

 reasons for it could be known. Thus, Austrian surgeons had noticed that 

 tetany was less common when the thyroid gland was resected at operations 

 for goiter than when one or both lateral lobes were extirpated. 



Chronic tetany was produced experimentally in dogs as far back as 

 1888. In that year W. S. Halsted had been puzzled by the development 

 of chronic tetany in animals in which he had ligated all the vessels, both 

 veins and arteries, of both lobes of the thyroid, with the exception of 

 the superior thyroid artery and the inferior thyroid vein. These dogs 

 suffered from chronic tetany and ultimately died, notwithstanding the 

 fact that the thyroid lobe enlarged after the operation and microscopically 

 showed a picture of hypertrophy. "Dogs so treated lived nearly three 

 months on the average, in contrast to those with thyroid extirpation, 

 which died usually in from two to nineteen days after operation." These 

 first recorded cases of chronic experimental tetany were probably due, as 

 Halsted himself suggests, to the cutting off of the circulation of both 

 superior parathyroids, by the ligature of the superior veins, and by the 

 handling incident to the ligation. The two internal parathyroids prob- 

 ably survived in these dogs as well as the hypertrophied thyroid, for, 

 if no parathyroid tissue had remained, the dogs could not have lived for 

 three months, as they usually did; they would have died within three 

 weeks of the acute and total abolition of the parathyroid function. 



That several of the forms of tetany other than tetania strumipriva are 

 also due to lack of parathyroid function is strongly suggested by the 

 identity of the clinical phenomena in these forms. It seemed highly im- 

 probable, Pineles urged, that this identity could be accounted for other- 

 wise than by the assumption of a common pathological-physiological basis 

 of hypoparathyroidism (unitary conception of the pathogenesis of tetany). 

 Studies of etiology later than those of Pineles suggest that the unity of 

 pathogenesis may lie in metabolic conditions (some of them parathyroge- 

 nous, some of them non-par athyrogenous) that cause the peculiar hyper- 

 excitability of the nervous system. 



The recognition that postoperative tetany is due to loss of para- 



