1923. No. 16. THE NELROLOGICAI. ASPECT OF LEPROSY. 73 



The prtrceding only refers to the "classical"* dissociation. As already 

 mentioned there are many other forms — and particularly one of them, viz. 

 a marked dissociation between the sensation to heat and to cold, is in my 

 opinon more an indication of a very peripheral, than of a spinal lesion '. 

 It is quite peripheral in the skin that we have the apparatus for the sensa- 

 tion of heat, and that for the sensation of cold, distinctly separated in form 

 of "heat spots" and "cold spots" with distinctly different localisation. Obvi- 

 ously then we have here favourable conditions for the production of a 

 dissociation between sensation to heat and cold. 



The palpable thickening of several nerves is an important point in 

 favour of the diagnosis of lepros}- (in early stages accompanied by consider- 

 able tenderness — in advanced cases by analgesia to pressure). 



The function of the bladder and rectiou is more frequently disturbed 

 in syringomyelia than in leprosy; — though disturbances of this kind are 

 not frequent in either. 



Finally, it has to be remembered that a leprosy patient may develop 

 syringomyelia, while, on the other hand, syringomyelia naturally does not 

 render the patient immune to leprosy. 



A circumscribed medullary or an cxtramedullary lesion (e. g. pachy- 

 meningitis) in the cer\ico-dorsal region of the cord ma\- cause the same 

 disturbance of the upper limbs as leprosy, but the lower limbs will also 

 here exhibit spastic phenomena. 



From myopathy and from progressive spinal miisenlar atrophy the di- 

 stinction is a rule easy, because in neither of these conditions does any 

 sensory loss ever obtain, while sensory loss in one form or other is, as 

 as we have seen, a fairly constant accompaniment of lepros}'. In myopathy 

 also the distribution of the muscular atrophy is different from that of lepros}-, 

 affecting the proximal parts of the limbs first. Only as regards the face, 

 the distribution may be said to coincide to a certain extent: but never in 

 myopathy have I seen that peculiar facial disturbance which in a previous 

 chapter I have described as typical of leprosy. 



In spinal muscular atrophy the lower limbs are, as a rule, not so pro- 

 foundly affected as the upper limbs. When the lower limbs are found 

 affected in that disease, they may be affected in the same way as the upper 

 limbs, but more commonly there are distinct signs of a pyramidal lesion 

 (viz. inversion of the plantar reflexes and exaggeration of the deep re- 

 flexes), in other words elements of an amyotrophic lateral sclerosis more 

 or less pronounced. The examination of the lower limbs will therefore 

 offer a great help in the differential diagnosis. In leprosy they are affected 

 in the same way as the upper limbs — there is a marked atrophy of the 



' This was suggested by Leegaard in 1892 for olt dissociations. 



