158 FRANKLIN C. McLEAN 



to be the underlying cause. In this form the association of edema with 

 other symptoms of heart failure, and the influence of gravity on the loca- 

 tion of edema, are the prominent features. Local edemas, from mechan- 

 ical causes, are common, and may be due to direct injury to the tissues, 

 by trauma or inflammation, or to interference with the venous or 

 lymphatic flow from an organ or region of the body. Ascites, in cirrhosis 

 of the liver, is associated with obstruction to the portal circulation. Other 

 local edemas may be due to venous obstruction, caused by pressure, throm- 

 bosis, or trauma, or they may be due to blocking of the lymph channels by 

 parasites ( Filar ia), or by trauma. Glaucoma is usually attributed to 

 mechanical obstruction to the lymph return from the anterior chamber 

 of the eye. 



Edema from chemical causes includes the edema of nephritis, in those 

 cases in which edema is not due to circulatory failure. It also includes 

 the so-called soda^edema. This form follows the administration of large 

 doses of sodium bicarbonate in certain conditions in which there is already 

 an abnormal metabolism, as, for instance, in diabetes or cachexia. Spon- 

 taneous edema is also common in cachexia- or inanition, especially in 

 infants or in the aged. Such cases have occurred in large numbers during 

 the past few years, especially in communities where there were enforced 

 dietary restrictions. This condition has been variously known as war- 

 edema, "oedemkrankheit" and famine-edema. It appears to be due to a 

 dietary deficiency, and especially to a diminished protein intake, continued 

 over long periods of time. 



.. r Protein poisoning is now commonly recognized as a cause of edema. It 

 Usually assumes either the form of urticaria, which is more or less limited 

 tfo the skin, or of the condition known as angioneurotic edema, which is 

 similar to urticaria, but involves the subcutaneous tissues as well and may 

 in addition involve the mucous membranes. The latter is also associated 

 with certain general manifestations and with disturbances in metabolism 

 (Miller and Pepper). These conditions may follow the oral or subcu- 

 taneous or intravenous administration of foreign products. Edema then 

 'occurs only in individuals sensitive to particular proteins, and edema 

 i3'a part of the general phenomenon of anaphylaxis. Individual sensi- 

 tiveness to a large number of foreign proteins has been found in otherwise 

 normal individuals. Unexplained urticaria and angioneurotic edema are 

 Usually attributed to food poisoning. They have a tendency to recur. 

 '' ~y -Neuropathic edema may be associated either with functional or 

 anatomical nervous disorders. It has been observed after section of a 

 peripheral nerve, and in transverse myelitis, syringomyelia, poliomyelitis, 

 and cerebral lesions. Although it has by no means been demonstrated, 

 it is generally assumed that this form of edema is due .-to vasomotor dis- 

 turbances. Hertz and De Jong have found renal disturbances in certain 

 cases with neuropathic edema, and state that in. the majority of cases the 



