1923. No. 16. THE NEUROLOGICAL ASPECT OF LEPROSY. 27 



the impression that the paresis is solely due to the atrophy. There is, 

 however, no valid reason to believe that this should be the case ; one sees 

 just the same thing in all chronic peripheral neuron lesions, e. g. progressive 

 spinal muscular atrophy — and on the whole, there is nothing in the clinical 

 reaction of the peripheral motor neuron and its muscle to the noxe, specific 

 of leprosy. Any noxe would produce the same result, provided its develop- 

 ment and progression were equally slow. 



To begin with the upper limbs, we find in leprosy the same condition 

 as in progressive spinal muscular atrophy, in amyotrophic lateral sclerosis, 

 in syringomyelia, (in short in any chronic lesion of the anterior horns in 

 the cervico-dorsal region of the cord I, in lower plexus paralysis, and in 

 some cases of polyneuritis of other origin of long standing — as, in fact, in 

 all chronic lesions of the peripheral motor neuron. 



One is struck by the atrophy of the intinnsic muscles of the hand, 

 first seen as a rule in the first interosseal space. One finds paresis or 

 paralysis of all these intrinsic muscles — and this paresis or paralysis is 

 accompanied by loss of tonus. This atonia and parah'sis of certain muscles 

 causes certain peculiarities. Thus the paralvsis and atonia of the opponens 

 poUicis causes what has been called the simian hand, generally described 

 as a characteristic of a paralysis of the median nerve; the thumb is kept 

 in more or less the same plane as the other fingers, and is not, as nor- 

 mally, rotated inwards tov.ards the palm of the hand. The similar disturb- 

 ance of the lumbricales and interossei causes a hyperextension at the 

 metacarpo-phalangeal joints and a flexion at the interphalangeal joints, — 

 the "claw hand", generally described as characteristic of ulnar paralysis. 



This combination of "claw hand" and "simian hand" is as characteristic 

 of leprosy as of progressive spinal muscular atrophy. 



As the disease progresses, the muscles of the forearm involved are 

 affected in just the same way (paresis, atrophy, hypotonia) and finally also 

 the arms and shoulders. But even in the oldest and most advanced cases 

 the muscles of the arms and shoulders are practically never affected to 

 any great extent. 



It is, in short, the usual distribution and the usual development of 

 motor loss in any polyneuritis that we find here. Sometimes the motor 

 loss in the area of a certain nerve predominates. We have already seen 

 that in most of the early cases it will be the motor loss in the distal parts 

 of the ulnar and median areas that predominates. In some cases an early 

 and typical radial paralysis has been described. Thus de Beurmann and 

 Gougerot described two cases of radial paralysis at the International Lep- 

 rosy Conference in Bergen 1909. It is, however, well to keep in mind 

 that lepers may as well as others develop a pressure paralysis of the 

 radial nerve. One must therefore be extremely careful in putting down a 

 radial paralysis to the specific action of the leprosy bacillus. 



