-yo G. H. MONRAD-KROHN. M.-N. Kl. 



On the whole, I think we can safely abide by the classical opinion 

 that the nervous manifestations of leprosy are due to a polyneuritis — and, 

 we may add, a polyneuritis of the most peripheral kind. 



As regards the progression of this neuritis, the clinical facts are all 

 in favour of the ascending nature of this polyneuritis ; but, if the distribution 

 of the cutaneous lesions be compared with the extension of the polyneuritic 

 manifestation, it will be seen that the peripheral nerves cannot always have 

 been attacked by a process ascending from a cutaneous lesion (as supposed 

 in Dehio's diagram). The cutaneous lesions would have to be much more 

 numerous and extensive to allow of such an explanation. 



The nerves are therefore no doubt often infected from the bloodstream 

 {metastatic or haematogenous infection). But once the nerve has been 

 attacked, the bacilli and their products are probably carried in a central 

 direction, causing an ascending neuritis of metastatic origin. • 



Thus one might suppose two kinds of ascending neuritis; 



ascending neuritis of metastatic origin, and 



ascending neuritis of cutaneous origin (as in Dehio's diagram). 



These reflexions based on clinical facts seem to harmonise with the 

 anatomical findings, which cannot, however, be discussed here. 



4. Diagnosis. 



It has to be admitted, perhaps, that in most cases the cutaneous mani- 

 festations are of the greater importance for the diagnosis. Yet the neuro- 

 logical findings very often furnish a necessary support for the diagnosis. 

 Ony might very aptly say that the diagnosis of leprosy rests with one leg 

 on the dermatologicai findings and the other on the neurological findings. 

 It not infrequently happens that one has to rely on the neurological findings 

 alone. It is still very doubtful whether cases of leprosy exist where nerve 

 lesions develop without there ever having been any cutaneous manifestations. 

 Men with such great experience as Danielsen, Armauer Hansen and Looft 

 deny the existence of such cases. Yet the cutaneous manifestations may 

 be very slight. And typical cutaneous manifestations may be altogether 

 absent at the time of examination. 



Even an attempt at finding the bacilli may fail; particularly when no 

 typical skin lesion can guide one in the excision of a suitable piece of skin. 

 And it is a well-known fact that in the maculo-anaesthetic variety of the 

 disease the bacilli are often so scanty that it is a matter of the greatest 

 difficulty — and of the greatest patience — to find them. 



Thus in a number of cases the diagnosis rests entirely on the neuro- 

 logical findings. The neurological differential diagnosis then becomes ex- 

 tremely important. It is this purely neurological differential diagnosis which 

 is dealt with in the followinsr lines. 



