THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 529 



In reading Charcot's lectures, one is struck by the accuracy of the observations, 

 made with so limited a histological technique, and one must admit that, in spite of 

 recent specific staining methods, little has been added to the classical histological 

 picture of Charcot. 



B. Primary Change in the Parenchyma. 



All the writers in this group regard the change in the myelin sheath of the nerve 

 fibre as the primary one: they contend that an infective or toxic "noxa" may act 

 directly and primarily upon the nerve fibre before there is any trace of glia prolifera- 

 tion, and without a primary vessel disease. 



Eedlich (1896) considers that the first impulse to the disease may be given, e.g. 

 by infective diseases, in such a way that there is brought about an acute degenerative 

 decay of the myelin sheath of the nerve fibre, analogous to that produced by experi- 

 mental infection of micro-organisms or their toxins. He thinks that the acute 

 degeneration of the myelin sheath finds an analogy in peri-axial neuritis, which like- 

 wise is found in toxic diseases. Redlich suggests that a further advance of the 

 disease may be caused by the original agent having caused, in addition to the evident 

 areas, an alteration in the nutrition of other portions of the central nervous system, 

 and later, through excess of function or strain, these parts may perish. 



The vessel changes are looked upon as accessory phenomena, for the great 

 irregularity in the distribution and form of the areas in the cord seemed to argue 

 against the dependence of the foci on the vessels. The interstitial changes in the 

 glia are regarded as dependent upon the parenchymatous degeneration, though it is 

 admitted that the absence of definitely proved areas in the peripheral nerves argues 

 for the presence of glia as essential to the process. 



Redlich thinks that all the actual histological changes found in disseminated 

 sclerosis may be found in other conditions, but their actual grouping is characteristic 

 of disseminated sclerosis. He distinguishes three types of areas : — 



(a) Very dense patches which consist of very fine parallel fibrils with glia cells 

 and nuclei. The processes of the cells are often very distinct, and give to the cell 

 the appearance of beautiful spider cells ; the cross-section of the fibrils gives the 

 impression of granules. Within these areas few myelin sheaths are left, and the 

 axis cylinders persist, but are swollen or atrophied. The transition to normal tissue 

 is a gradual one. 



(b) A large-meshed tissue with thickened glia trabeculae but no definite area. 

 In this tissue the vessels are more or less changed, the walls frequently hyaline, and 

 the peri-vascular glia increased. 



(c) A wide-meshed network with glia trabeculse only slightly thickened. The 

 nodal points of this meshwork are occupied by glia cells with their processes ; the 

 meshes are empty because the nerve fibres have completely perished, and the tissue 

 has an areolar appearance. In the neighbourhood of these areas are found nerve 



