196 DISEASES OF THE BRAIN. 



1. Those that diminish the entire amount of blood in the organ. 

 Among these belong not only abstractions of blood and spontaneous 

 haemorrhages, but extensive losses of fluid, considerable exudations, 

 pnd tedious, particularly feverish, diseases. Unfortunately, it occasion- 

 ally happens that, in internal haemorrhage, anaemia of the brain is mis- 

 taken for hyperaemia, and treated accordingly. The form of the dis- 

 ease which, since the time of Marshall Hall^ has been known as hy- 

 drocephaloid, is particularly common in children who have suffered 

 from continued diarrhoea. Typical examples of this are not unfre- 

 quently seen as a result of extensive hepatization in weak persons 

 with pneumonia. But protracted fevers also consume the flesh and 

 blood of the patient, induce general poverty of the blood, and, as one 

 symptom of it, anaemia of the brain. In all of these diseases, blood 

 and the fluids of the body are lost or used up too rapidly ; on the 

 other hand, the amount of blood may be diminished by its formation 

 being limited from insufficient supply of nourishment. Thus, in per- 

 sons who have died of starvation, the most marked symptoms of anae- 

 mia of the brain have been observed before death (as Gerstenberg has 

 described in his " Ugolino," in very vivid terms, it is true, but still 

 quite accurately). 



2. This affection not unfrequently results from the overloading of 

 other organs with blood. The best example of this form are the cases 

 where it is induced by the application of JunocTs cupping-boot, by the 

 injudicious use of which the anaemia may readily become dangerous. 

 This also explains why, when the heart's action is weak, a person 

 faints more readily when standing up than when lying down. It is 

 evident that, in the upright position, the lower extremities will become 

 overloaded with blood, if the propelling power is insufficient to over- 

 come the obstruction caused by the weight of the venous blood in this 

 long course. On the other hand, in diminished action of the heart, 

 the obstruction from the weight of blood in the short carotid artery 

 must have a very inferior influence on the occurrence of anaemia of the 

 brain in the upright position. 



3. Another cause is compression or obstruction of the arteries sup- 

 plying the brain. In almost all of the cases of this class that have 

 been reported, the obstruction was artificially caused by ligation of the 

 carotid. In a few cases only the carotid or vertebral arteries were 

 compressed by tumors or closed by emboli. 



4. Cases where, from mental excitement, without lessening of tht* 

 heart's action, there are paleness of the cheeks and even loss of con 

 sciousness and other symptoms of insufficient supply of blood to the 

 brain, seem to indicate that anaemia of the brain may also be caused 

 by abnormal innervation or spasmodic contraction of the arteries. 



