44 SURGICAL SHOCK 



the first place, he shows that it only affects those 

 segments of the cord distal to the lesion ; thus, after 

 an upper dorsal transection the cervical segments 

 are not in shock. Secondly, he shows that after 

 recovery has taken place, a second transection — for 

 instance, in the mid-dorsal region — will not repro- 

 duce the signs of spinal shock, proving that it was 

 due to the withdrawal of influences descending 

 from the brain or brain stem. Again, cutting across 

 the mesencephalon, above the pons, does not in- 

 duce spinal shock. Therefore the impulses pre- 

 venting it must have come down from the region 

 of the fourth ventricle. We also know that from 

 this same region, and in particular from the central 

 nuclei of the vestibular nerve, descend the impulses 

 which give rise to excess of muscular tone. A 

 transection of the mid-brain causes decerebrate 

 rigidity of the limbs ; a second transection below 

 the medulla abolishes the excess of tone. On this 

 subject the writings of Sherrington and of Thiele 

 may be consulted. 



F. H. Pike, of Columbia University, has lately 

 published a very important research on spinal shock 

 with particular reference to the blood-pressure. He 

 shows that there is a certain residual blood-pressure, 

 about 33 mm. of mercury, even after removal of the 

 brain, provided that the cord is left intact, and that 

 sensory stimuli will raise this pressure reflexly. 

 When the cord is totally removed there is a very 

 great fall of pressure. Apart from removal of the 

 cord, curare produces a considerable reduction of 

 blood-pressure, both in normal and in spinal animals. 



