DIABETES INSIPIDUS HI 



perhaps all of them have played a part, and it is possible that upon the basis 

 of such difference in the manner of production a separation of the varying 

 clinical pictures into individual groups may be made. In such an attempt, 

 however, we can hope for nothing more than partial success. 



One group of cases in which clinical observation or an anatomical finding 

 shows organic disease of the brain can be sharply defined. Since Claude Ber- 

 nard's celebrated experiments have shown that by injuring an area in the 

 floor of the fourth ventricle (close to the glycogenic center) simple polyuria 

 may be produced, many cases of this type of diabetes insipidus have been col- 

 lected, and it has been determined that in the majority of these cases there 

 has been a definite change in the posterior cerebral areas, particularly in the 

 region of the sinus rhomboidalis. 



These. cases are in harmony with the teachings of physiology; thej' form 

 a well-defined, genetically connected group, and though we may be in doubt 

 whether certain cases belong in this category or not, this doubt is due to the 

 fact that in these instances the alterations attributed to the brain are indefinite. 



Only a small proportion of all cases belongs to this group. Among the 

 remainder, a group may be separated in which the increased excretion of 

 urine is simply the result of an increased ingestion of fluid. In a number 

 of cases it has been found that by limiting the ingestion of water, gradually 

 or suddenly, we produce a short period of discomfort followed by cure of the 

 disease. Here the obvious explanation is that the caiise of the troiiMe is sim- 

 ply an increased ingestion of fluid whether due to an unexplained thirst or 

 to habit; in short that polydipsia is the trouble. 



Eegarding many other cases it must remain questionable whether they 

 should be included in this group, partly because some symptoms are opposed 

 to this idea, partly because the decisive test of limiting the ingestion of fluid 

 cannot be carried out. 



Still other cases are proved by special characteristics in the clinical pic- 

 ture to depend upon an increased excretion of water by the kidneys, inde- 

 pendent of the ingestion of fluid. The facts which justify this explanation 

 are : First, a diminished excretion of water by the skin and lungs in spite of 

 the great natural afflux of water to these parts and, as a more easily recognized 

 expression of this condition, an excessive amount of urine as compared with 

 the amount of fluid ingested ; naturally the implied diminution of the amount 

 of water normally ingested is at the expense of the water consumed with solid 

 food. Secondly, we note the independence of the excretion of urine upon the 

 ingestion of water, so. that, for example, after a sudden stoppage of the intake 

 of fluid, the production of urine continues unchanged, at any rate during the 

 next few hours. 



These conditions, polydipsia and true polyuria, are in practice very diffi- 

 cult to separate, and, in spite of much labor which some authors have bestowed 

 upon this point during the last decades of the preceding century, the sepa- 

 ration of these forms has not gained general acceptance. So it is with the 

 attempt made by Schapiro and others to distinguish a form of diabetes 

 insipidus due to disease of the abdominal sympathetic and to characterize it 

 clinically; it is not convincing. 



