272 CHEMOTHERAPY 



pointed out, the toxicity of the salvarsan is distinctly less than that 

 of mercury. 



Neurorelapses. Not infrequently certain functional disturbances 

 have been noted to occur in connection with some of the cranial 

 nerves, which appear very soon after the injection. Ehrlich is 

 inclined to look upon these as corresponding to the so-called Herx- 

 heimer reaction, which is so frequently observed in the skin soon 

 after the use of salvarsan, and which he refers to the liberation of 

 toxins from the killed spirochetes and to their local irritating effect. 

 He points out that if such a reaction should affect one of the cranial 

 nerves at a point where this passes through a narrow, bony canal, 

 disturbance in function would be a very probable consequence, 

 owing to swelling and resultant compression. Such disturbances, 

 however, do not occur within a few hours of the injection, as in the 

 case of the true Herxheimer reaction, affecting the skin, but only 

 after twenty-four hours, or even after three or four days, as the 

 vascular supply of the nerves is but little developed, and a longer 

 time must elapse before a sufficient number of spirochetes has been 

 killed to produce a local reaction of moment. Owing to the same 

 cause, an opportunity is afforded in these localities for the escape of 

 some of the spirochetes and their subsequent development. Should 

 the spirochetal focus be very small in comparison to the size of the 

 nerve at the point in question, so that no pressure would result 

 in consequence of the first Herxheimer reaction, there will, of course, 

 be no occasion for the development of acute symptoms. But if, 

 then, the surviving spirochetes increase in number a basis would 

 be furnished for what is now commonly termed a neurorelapse. 



When these relapses, which usually occur two or three months 

 or even four or five months after treatment, were first observed, 

 following the use of salvarsan, they were attributed to the contained 

 arsenic and were supposed to constitute a special danger attending 

 its use. But as Ehrlich has pointed out, the same occurrences have 

 been noted in connection with the use of mercury, and to judge from 

 the collective reports of Benario they are no more frequent after the 

 use of salvarsan than after that of the latter, and here as there the 

 same nerves are especially prone to attack, viz., the auditory, the 

 optic, the facial, and the oculomotor, while the fourth, fifth, sixth, 

 and twelfth are much less frequently affected. 



Ehrlich emphasizes in support of his view that neurorelapses only 



