360 LEWIS J. POLLOCK 



area of nerve overlap,^ and that this return of sensibihty to pin 

 prick cannot be interpreted as a sign of nerve regeneration. 



T am sii])ported in this view by the facts that I have never 

 found a return of sensibility to pain, when sensibihty to touch 

 has not returned, except in an area of overlap; that when a 

 nerve is divided and at the same time one or more adjacent 

 nerves are divided sensation to pin prick does not return in the 

 area of the overlap of these nerves even many months following 

 the injury; that when a nerve adjacent to one which is severed 

 and which supplies an area of overlap to that nerve is sectioned, 

 the preexisting sensibility to pin prick in the overlap area is 

 lost; that when sensibility to pin prick is present in the anatomic 

 distribution of a severed nerve, resection and suture has no 

 effect on the general outline of this area of sensibility. 



MATERIAL 



My observations were made on 500 patients with peripheral 

 nerve lesions seen early in Base Hospitals in France and 523 

 patients with peripheral nerve lesions studied later at U. S. 

 Army General Hospital No. 28, Fort Sheridan, 111. 



The observations of early peripheral nerve lesions were in 

 most instances uncontrolled by operative procedures. A large 

 proportion of the lesions were partial and frequently compli- 

 cated by injuries to adjacent small sensory branches. But these 

 observations served a useful purpose. They showed: 1) that in 

 many cases for the first two or three weeks only a very small 

 area within the border of the part insensitive to cotton wool 

 was sensitive to pin prick ; 2) that in a few a larger zone sensitive 

 to pin prick appeared within fifteen days; and 3) that the return 

 to sensitiveness to pin prick in a larger zone, corresponding to 

 the area which we later determined as overlap usually was 

 found, at times variable from thirty to one hundred days. The 



1 By 'overlap' is meant the presence, or assumption of function of sensation 

 by adjacent nerves within the anatomic sensory distribution of a severed nerve. 

 By 'overlap area' is meant that area in which such function is possible through 

 such an agency. 



