BRAIN. 127 
Secondary hydrocephalus, seen in children and adults. 
Primary hydrocephalus, seen in adults. 
What are the causes of and changes seen in these different forms ? 
The first form develops at or soon after birth. The accumulation 
of fluid in the ventricles may crowd the brain tissue into a thin layer 
or cause its destruction. The bones of thé skull may bulge out and 
the head become enormously enlarged. In the second class of cases 
the condition may be the result of some form of meningitis, of alcohol- 
ism, or of the general paralysis of the insane. As the cranial bones are 
better developed changes in the size and shape of the head are unusual. 
The cause of the last form is not well understood. It usually occurs 
in adults past thirty years of age. 
‘What tumors occur in the ependyma ? 
Fibromata, lipomata, angiomata, sarcomata and gliomata. 
What pathological changes have been noted in the pineal gland ? 
It may become hypertrophied and hard or be the seat of small cysts, 
or may participate in inflammatory changes involving adjacent parts. 
What pathological changes may occur in the pituitary body, and 
what tumors have been seen in it ? 
Simple inflammation extending from adjacent parts. Tubercular 
and syphilitic inflammation, 
Adenomata, sarcomata and carcinomata may occur. 
What are the causes of thrombosis and embolism in the cerebral 
arteries ? 
-Thrombi may be found as a result of pressure upon a vessel from 
without, or from degenerative or inflammatory changes in the wall of 
the vessel. Emboli may arise from an acute or chronic endocarditis 
or cardiac thrombi, or from atheroma of the aorta, carotid or vertebral 
arteries, 
What effects are produced by thrombi or emboli ? 
If a large vessel is blocked up by an embolus the patient may die 
suddenly. Ifa smaller vessel is blocked up by a thrombus or embolus 
the region which is supplied by the vessel is deprived of blood. If 
there are anastomosing branches to the occluded vessel a collateral cir- 
culation is established, but if a terminal artery becomes stopped up the 
brain tissue to which it is distributed may become degenerated and 
softened. 
