PHYSIOLOGY OF SPINAL CORD 139 



I have taken the blood-pressure in two patients 

 whilst four or five nerve-roots in the lumbar and 

 sacral plexus were cut on each side, and there has 

 been no sudden fall. There was a steady drop 

 throughout the whole operation (under open ether 

 anaesthesia) amounting to less than eight millimetres of 

 mercury. 



8. Certain degenerative changes. The posterior 

 columns of the spinal cord show Wallerian degenera- 

 tion running up to their termination in the gracile 

 and cuneate nuclei of the medulla. As Warrington 

 and others have shown, in animals the cells of the 

 anterior horn on the same level as the severed roots 

 show signs of chromatolysis, or dissipation of their 

 Nissl granules. I have recently been able to demon- 

 strate this in man. A patient who had been treated 

 for gastric crises by resection of the posterior nerve 

 roots from the seventh to the tenth dorsal, died about 

 two months afterwards. In the cervical region all 

 the nerve-cells were normal, but in the region of the 

 divided roots more than half the anterior horn cells, 

 and all the cells of Clarke's column, showed marked 

 chromatolysis. This is interesting in the light of the 

 various affections of the motor functions just 

 mentioned. 



The surgery of the posterior nerve roots is yet in 

 its infancy, but it promises to have a future. When 

 it is resorted to earlier, it will most probably have a 

 greater value. 



There are two main indications for dividing the 

 posterior nerve roots. The one is pain, and the other 

 extreme rigidity, in the course of spastic paraplegia 



