244 DISEASES OF THE NERVOUS SYSTEM 



you see it originate, in connection with some infectious or toxic disease 

 (distemper, rabies, pyaemia) due to the specific toxic material locating 

 in the cord. It may also be caused by cold, being continually wet and 

 frozen, as in retrievers. 



Pathological Anatomy. — The inflamed pia mater appears thickened, 

 infiltrated, and may be injected in some places and, as a rule, adherent to 

 the vertebra, due to the organization of the exudation. It is covered 

 on its upper surface by a serous, fibrinous, or purulent exudation. The 

 arachnoid exudation is covered by a milky, false membrane and greatly 

 thickened. The dura mater is rarely involved, but when such is the case 

 it becomes thickened and loosened and covered with a thin serum. The 

 spine itself shows the inflammatory process either extended over large sur- 

 faces or else confined to small centres. In the early part of the disease, 



Fig. 94. — Paralysis of the posterior extremities. 



the cord is slightly swollen; the gray substance is somewhat reddened, 

 dark and soft. Later the cord becomes a yellowish-red, breaks down and 

 undergoes white, yellow, or red degeneration. In the chronic course of 

 the disease we see atrophy of the nerves as a conscc{uence of nuilforma- 

 tions of the connective tissue. 



Clinical Symptoms. — As a rule the symptoms of alteration of the spinal 

 cord appear gradually and become more intense as the disease progresses. 

 Where the disease is due to violent traumatisms, producing a direct 

 destruction or laceration of the nervous centres, or pressure, caused by 

 hemorrhage and blood l)eing discharg(Ml and pressing upon the spine the 

 symptoms are immediately seen or appear in a very short time. In all 

 diseases of the spinal cord it is very inij)ortant to recognize the fact that 

 consciousness is rarely affected. We will take up all these symptoms in 



