NERVE INJURIES 195 



disintegration of the nervous matter lays down a line 

 of bait to entice the regenerating fibres along paths 

 of usefulness. 



The phenomena of repair after suture next call 

 for remark. It may be said at once that the sooner 

 the operation is performed the better will be the 

 results. If the muscles have ceased to contract to 

 any form of electrical stimulus, operation is useless. 

 It is very seldom that benefit will be obtained if 

 two years have elapsed since the injury. When 

 secondary suture fails to give a good result, the 

 fault hes not with the degenerated nerve fibres so 

 much as with the nerve cells in the spinal cord. If 

 asepsis is secured, accurate primary suture seldom 

 if ever fails. 



Sherren gives average time relations as follows : — 



5-25 weeks : Commencing return of protopathic 



sense. 

 6-12 months : Complete return of protopathic 



sense. 

 12-18 months : Return of epicritic sense. 

 12-24 months : Motor recovery. 



Taking the ulnar nerve as an example, recovery 

 may be hoped for in twelve months when it has been 

 divided at the wrist, or in twenty-four months when 

 the injury was at the elbow. 



During recovery, a remarkable phenomenon has 

 been described by Trotter, who had nerve sections 

 performed upon himself. Any stimulus over the 

 cutaneous area affected gives rise to a decidedly 

 painful sensation, referred usually to the most distant 

 part of that area. 



