in] Post-amputation Cha-nyes in the Cerebral Cortex 47 



B. The Cortex in cases of Amputation of Extremities. 



On running through the literature dealing with the changes in the central nervous system 

 ii|' individuals who have been disabled by amputation of one or other extremity, records of 

 several cases will be discovered in which the observers claim to have seen a naked-eye 

 atrophy of portions of the central convolutions, and the presence of these changes has even 

 been advanced to support physiological findings and throw light on the question of cerebral 

 localisation. I need hardly say, however, that observations of this nature are unreliable, and 

 it any doubt on the point still remains, I may mention that I have now had the advantage 

 of inspecting quite a large series of hemispheres from such cases, 22 to be exact, and in none 

 have I been able to satisfy myself of the existence of a definite, localised, macroscopic atrophy 

 which could be referred to the amputation ; and as a matter of fact one knows now that 

 although the microscope brings to light histological alterations in certain elements in such 

 cases, these changes are decidedly not so gross as to occasion a positive macroscopic shrinkage 

 of the gyms. 



Therefore, I cannot help thinking that the observers referred to, paying too little heed 

 to the general instability of gyral conformation, have mistaken natural localised attenuations 

 of convolutions for atrophy. The correctness of my assumption gains in probability from the 

 statement made in more than one of these records that microscopic examination yielded no 

 confirmation of the apparent atrophy. 



Now, as to my reasons for examining the brain in cases of amputation, and the nature 

 of the resulting change which I expected to find therein, it may be explained that it is 

 a lung-known and well-established fact that in consequence of such a lesion alterations occur 

 in the spinal cord, and these in course of time occasion striking and characteristic appearances. 

 In long-standing cases the predominant change is a homolateral atrophy, represented by" 

 a general reduction in volume of white and grey matter alike, and involving those particular 

 segments of the cord which receive and give off the sensory and motor nerves which originally 

 supplied the skin and muscles of the amputated member. Wasting of the grey substance 

 is accompanied by a numerical reduction of its contained nerve cells, both large and small, 

 and while all the cell collect inns in the anterior cornu suffer, one special group may be 

 singled out as being specially prone to atrophy, namely, the postero-lateral. As to the white 

 substance, it is a remarkable fact that in spite of this cell atrophy, the pyramidal tract, 

 beyond being reduced in size, does not exhibit any marked change in staining reaction, and 

 only a very minute fraction of the well-known sclerosis which we see left in it by a previous 

 descending degeneration. 



Arising from the discovery of these cell changes in the anterior cornu in cases of 

 amputation, a vigorous investigation of the whole subject concerning the reaction following 

 interference with the motor neuronic system, either by section, excision or evulsion of nerves, 

 has been carried out from the experimental side, and of the many workers in this field, 

 Homen, Marinesco, Lugaro, van Gehuchten and Warrington may be specially named. 



A title which has been applied to the various changes which have formed the subject 

 of these studies is "retrograde degeneration," but expressive and suitable as this designation 



