794 THE XEKVOUS SYSTEM. 



the term hcematomyelopore has been applied by Van Giesou. 1 To a simi 

 lar condition in which proliferation of the neuroglia is the most marked 

 feature, the name of "false or secondary syriugoniyelia " has been given. 



THROMBOSIS AND EMBOLISM. 



Thrombi may form in the arteries as a result of any degenerative or 

 inflammatory process in their walls leading to a roughening or death of 

 the intima, or from pressure from without, or they may occur in vessels 



FIG. 530. HiEMATOMTELOPORE. 



T*e section shows at one point a cyst-like cavity in the spinal cord, originating in a haemorrhage in the 

 posterior root (see Fig. 519) and extending nearly the entire length of the cord. The cavity is lined by tis- 

 sue detritus and neuroglia. 



in whose walls we can detect no primary lesion. The most common 

 causes are atheroma and simple endarteritis. Thrombi may also form 

 around an embolus which does not entirely occlude the vessel. 



Emboli of the cerebral arteries most commonly arise from acute or 

 chronic endocarditis or cardiac thrombi ; they may arise from aneurisms 

 or atheroma of the aorta, from the carotid or vertebral arteries, or from 

 the pulmonary veins. The materials constituting emboli vary greatly, 

 depending on their mode of origin (see page 76). The effects on the 

 brain tissue of emboli and thrombi of the arteries are essentially the same 

 in their main features. In some cases, however, in which large emboli, 

 usually from endocarditis, suddenly block up a large vessel, the individ- 

 ual may die almost instantly without other apparent lesion than the stop- 

 page of the vessel. 



1 Van Gieson, " Haematomyelopore a New Spinal-Cord Disease." New York Poly 

 clinic, 1897, vol. x., p. 87. 



