CEREBRAL HEMORRHAGE. 425 



ANEMIA. 



Anaemia of the brain may depend on general anaemia, or in 

 acute cases be due to severe hemorrhage. The condition is 

 supposed to occur during sleep, in fainting spells and hysteri- 

 cal crises. 



The gray and white matter on section appear much whiter 

 than normal, and the small puncta vasculosa are almost en- 

 tirely absent. A local anaemia may result from partial 

 obstruction of the blood-supply by a thrombus or embolus, 

 or the external pressure of a tumor. 



HYPEKffiMIA. 



An acute hyperaemia of the brain may be produced by ex- 

 cessive activity of the heart's action, and accompanies exces- 

 sive brain-work, sunstroke, acute delirium, and some infectious 

 diseases, as cholera and hydrophobia. 



A passive hyperaemia may result from valvular disease of 

 the heart and from interference with the return circulation 

 through the jugular veins by pressure of a tumor, or by dis- 

 ease of the lungs as extensive pneumonias and large pleuritic 

 effusions. The brain is enlarged, the bloodvessels of the pia 

 mater injected ; the gray matter may have a diffuse rosy tint, 

 and on section the puncta vasculosa are more conspicuous 

 than normal. In passive hyperaemia, however, the gray 

 matter has a slaty color and the sinuses and cortical veins are 

 widely distended. (Edema of the brain may result if the 

 condition is long continued. 



CEREBRAL HEMORRHAGE. 



The clinical term apoplexy is still used synonymously with 

 cerebral hemorrhage, of which it is the most striking symptom. 



The most important factors in the production of cerebral 

 hemorrhage are increased blood-pressure and the degenerative 

 changes occurring in the bloodvessel-walls with advancing 

 years, and in the course of various diseases, notably syphilis. 

 The resulting clots vary greatly in size ; they may be as small 

 as a pea, or almost entirely occupy one hemisphere. Usually 

 there is but one clot. They occur most frequently in the 



