NERVE OVERLAP — PAIN SENSE PERIPHERAL NERVES 373 



4. EFFECT OF RESECTION AND SUTURE ON SENSIBILITY OF AREA 



IN WHICH THERE HAS BEEN DISSOCIATED RETURN 



OF SENSIBILITY TO PAIN 



The conditions necessary to study profitably the effect of 

 resection and suture of nerves on return of sensibiUty to pain 

 are: first, that the nerve ends be separated and, second, that the 

 examination subsequent to operation be made within the period 

 of time ascribed to the return of protopathic sense as the result 

 of regeneration. 



Some difficulty is encountered in meeting the second condi- 

 tion, inasmuch as frequently the wide separation of the ends of 

 the nerves makes it necessary to place the extremity in a posi- 

 tion which will permit approximation, and to fix it in such a 

 position by means of a cast. This often prevents an examina- 

 tion before six weeks have elapsed. None of the cases here 

 reported were examined later than fifty days after operation, 

 one in less than fifteen days. Although some objection may be 

 made to the cases examined over forty-five days after operation 

 on the grounds of beginning return of protopathic sense due to 

 regeneration, the similarity of the areas unaffected by operation 

 in cases examined under forty-five days and those between 

 forty-five and fifty, coupled with the fact that the ends of the 

 nerves were separated in all of these cases, makes it reasonable 

 to admit them into the group. 



The areas which are sensitive to pin prick in the lesions exam- 

 ined, and the sensory changes following operation need only be 

 illustrated. It is sufficient to state that the following nerves 

 were studied: ulnar, examined forty- two days after operation; 

 ulnar and median, forty-five, thirty-six, forty, forty-six, forty- 

 eight and fourteen days after operation; external popliteal, 

 forty-eight, thirty-six, twenty, and twenty-six days after opera- 

 tion; sciatic, fifty and thirty-six days after operation (figs. 

 9 and 10). 



Following resection and suture when sensibility to pain is 

 present in an area of overlap, although some change" in the out- 

 line of this area occurs, in general the area remains the same. 



