196 NERVE INJURIES 



Recovery after incomplete division of a nerve is 

 more rapid, usually taking less than six months for 

 sensory restoration ; it is perhaps a year before 

 motor power is normal. Protopathic sense does not 

 return before epicritic, as it does when the nerve is 

 completely divided ; they are restored side by side 

 at an equal rate. 



The last point we shall consider is how best to 

 proceed when so much nerve has been lost that the 

 ends cannot be got together. Many methods have 

 been adopted, some of which are of little or no value 

 and should be allowed to drop out of use. Amongst 

 these may be mentioned the introduction of a bridge 

 of silk or catgut, or of nerve derived from a cat, dog, 

 or rabbit (which will undergo dissolution), and the 

 device of sphtting the nerve longitudinally and turn- 

 ing down one-half across the gap. It is quite evident 

 why these fail. The silk, catgut, and probably the 

 animal's nerve, cannot provide the necessary chemical 

 attraction for the down-growing nerve fibres. The 

 splitting " en-Y " does not lay down a continuous 

 " scent " along the tract ; it is broken at the stem of 

 the Y. Infinitely better results may be obtained by 

 suturing into the interval a length of human nerve. 

 This may be obtained from an amputated limb, but 

 it is always possible to excise several inches of some 

 unimportant nerve such as the internal cutaneous 

 of the arm, and if this is too slender, two or more 

 pieces may be used parallel to one another. The 

 nerve can be located before the anaesthetic is given 

 by testing with an electric current ; when the 

 electrodes are applied over the nerve a tingling or 



