DISEASES OP NERVES 257 



«ased, the electric conductivity of nerves and their muscle 

 ■endings produces alterations in their reactions to electric 

 stimuli. 



0/ what value is the reaction of degeneration to the surgeon ? 

 It is very important in the diagnosis and prognosis of a 

 paralysis. 



What forms of electricity are used to test electric properties of 

 muscles f 



The induced or faradic current and the constant or gal- 

 vanic current. 



What does the presence of the reaction of degeneration indi- 

 cate ? 



It points positively to structural changes in the diseased 

 jarts. 



JSow soon does a paralysed nerve lose its electric excitability ? 

 In about fourteen days. 



Sow soon does a muscle lose its electric excitability 9 



Muscles soon cease to react to the faradic current, while 

 Trhen exposed to the galvanic current their excitability is at 

 first increased, to lose itself in four to eight weeks — that is, 

 ihe muscular contraction , becomes slower and slower at the 

 make and break of the constant current (as the current is 

 allowed to pass or is interrupted). 



Upon what featwres is the diagnosis of cerebral paralysis 

 based? 

 The paralyzed area is, as a rule, extensive— hemiplegia ; 

 hut may be a monoplegia, only involving one cranial nerve; 

 then reflex action is present and degenerative atrophy is 

 wanting. 



