THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 635 



The " volitional " tremor and scanning speech are also symptoms of the very 

 greatest importance. They are both the result of defects of co-ordination. The 

 tremor occurs only on voluntary movement and is absent during rest. In attempting 

 to carry out any movement the arm jerks about in an irregular manner, the tremor 

 becoming quicker towards the end of the voluntary act. This form of involuntary 

 movement, we know now, results from affection of the cerebello-rubro-thalamo-cortical 

 path. Injury to this path allows involuntary movements to occur by removing the 

 steadying influence which it normally exerts upon the Betz cells in the motor area. 

 If this influence be removed, steady innervation of the anterior horn cells is impaired, 

 and the more the pyramidal path is innervated, the more obvious does the tremor 

 become. Involvement of the cerebello-rubro-thalamo-cortical path may occur, thus, 

 at many different levels, and any of these lesions may result in this volitionary 

 tremor. That this path is specially liable to be affected is well seen in these cases 

 here described, as in most of them patches were found at many different levels. 

 They occur very frequently in the superior cerebellar peduncles, in the red nucleus, 

 and in the optic thalamus. 



The relation of the symptoms to the areas of sclerosis found after death is well 

 seen in Case I (L. W.). The symptoms in this case began with weakness of the legs, 

 which passed off, recurred, grew rapidly worse, and terminated in a spastic paraplegia. 

 This is obviously the clinical manifestation of the dense areas of sclerosis which were 

 found throughout the spinal cord. These were obviously of long duration, and seem 

 to have been the earliest manifestation of the disease. The patches which were found 

 in the sacral region were also of an early date, and were responsible for the affection 

 of the sphincters from which she suffered. The spinal cord lesions in this case were 

 thus very extensive and appeared at an early stage of the disease. 



The next symptom of importance to appear was the volition tremor, with which 

 we associate the patches in the superior cerebellar peduncle, red nucleus, and optic 

 thalamus. These appeared also at a fairly early stage. The nystagmus was also an 

 early symptom, and was undoubtedly associated with the peri-ventricular and peri- 

 aqueductal sclerosis, only parts of the oculo-motor nucleus being involved. 



After a short time the symptoms followed each other rapidly. An extension of 

 the patches in the cervical region caused sudden numbness in the left arm. This was 

 followed by a rapid development of large patches in the pons, one of which, involving 

 the VHIth nerve, produced deafness in the right ear, and another, catching the facial 

 nucleus, produced a right facial paralysis. These patches were found in an early 

 stage and thus appeared late in the course of the disease. An extension still later 

 of a patch involved the sixth nucleus, and led to diplopia from paralysis of the 

 external rectus muscle. This was soon followed by the medullary patches which 

 involved the Xllth nerve and nucleus, and led to a protrusion of the tongue to one 

 side and slight difficulty in speech and swallowing. Later the vision suddenly 

 became dim, and next morning she became totally blind. This was obviously the 



