CONCUSSION. Ill 



such as violent and sudden concussion, suspends tlie action of 

 the heart, and thus proves fatal by syncope or death beginning 

 at the heart. The vital powers of the heart seem to be destroyed, 

 for when the chest is opened immediately after death, it is 

 impossible to excite contraction of that organ. 



The difference between the effects of concussion and a wound 

 of the brain is very remarkable. Mayo observes on this sub- 

 ject — "A great part of the brain of an animal may be gently 

 and quietly sliced away with little or no effect ; but if ever so 

 small a portion be suddenly crushed, the heart stops directly." 



Again, from the experiments of Chossart and others, there 

 appears some variety of opinion as to the part of the circula- 

 tion chiefly affected by certain injuries of tlie nervous centres. 

 In certain injuries of the brain and spinal cord, Chossart found 

 that the capillary circulation appeared for a time to be more 

 affected than the heart's action ; but still it is by failure of the 

 circulation that such injuries ultimately prove fatal. It is only 

 by such knowledge as this that the practitioner can be guided 

 to rational and scientific treatment. A peculiar fact may be 

 introduced here, as exemplifying a lesion which occurs very 

 frequently after the operation of pithing (dividing the spinal 

 cord between the occiput and atlas, or atlas and dentata), 

 namely, rupture of the vena azygos. 



In some cases, when death occurs from concussion, the heart 

 is found quite empty, a condition that is not easily accounted 

 for. In other cases it is distended; but the distinguishing 

 peculiarity is, that there is no difference in the quantity of blood 

 in its right and left sides. 



" We may sum up by stating " (says Pirrie) " that when con- 

 cussion proves fatal in the first stage, it is by failure of the 

 action of the heart, which is sometimes instantaneous, some- 

 times gradually increasing to a fatal termination ; and some- 

 times there is a very partial reaction, and then a second failure 

 of the organs of circulation, which proves fatal." — (Piekie, 

 Principles and Practice, of Surgery.) 



Bearing these facts in remembrance, the practitioner will 

 watch the state of the organs of circulation with care and 

 anxiety. Another way in which concussion proves fatal is by 

 compression, arising from extravasation of blood, serous effusion, 

 or the formation of pus. 



