SECONDARY DEGENERATIONS OF THE SPINAL CORD. Comparatively recent observations in nervous diseases have proved that when a nerve fibre is injured in any part of its course, it undergoes certain degenerative changes in that portion which is cut off from its connection with the nervous centre, from which it derives its supply of nerve force. In other words the alteration commences at the seat of the lesion and proceeds in the direction of the transmission of nervous force. If, therefore, we have any disease interesting the brain or upper part of the spinal axis, by which certain fasciculi of nerve tubes are destroyed, we can trace these degenerated tubes throughout their course along the spinal cord, observing with accuracy whether they terminate in the gray matter of the cord or pass off in the anterior roots of the rachidian nerves. In the same manner lesions of the posterior roots, or lower segments of the cord result in such alterations of the posterior columns as to admit of our tracing the injured tubes in a centripetal direc tion. It being well proved that the ultimate nerve fibres do not anastomose with one another, but continue their course distinct and separate from their peripheral to their central extremity, we have a reliable method of studying each individual nerve throughout its passage along the cord, as well as of investigating its relations to the central ganglia, by carefully observing the alterations which are secondary to primary lesions of the nerve tissue. This power of following a nerve tube along its course is of inestimable value in investigating into the pa thology and physiology of the nervous system; and accurate observations of cases will doubtless result in a great advance in our knowledge of this complex and difficult subject. I have translated the following work of Bouchard upon secondary degenerations of the cord, in hope that it will lead those who have opportunities of meeting with such cases to keep careful records of the symptoms and post mortem appearances, which, when tabulated and compared with one another will doubtless serve to elucidate some of the difficult problems which are so continually presented to us by the nervous system. ALBANY, NOV. 22d, 1868. E. R. HUN. Besides the lesions proper of the spinal cord which result from a primitive alteration of its tissue, there are others which occupy, as a rule, the whole length of the rachidian axis, which develop very rapidly and almost at the same time throughout this whole extent, and follow either primitive lesions limited to one point of the cord itself, or lesions of the brain, or lastly alterations of the posterior roots. These secondary degenerations of the cord take no part in the proceedings of the primary lesion. They have their own physiology and pathological anatomy, their special course, the same in every case, whatever be the nature of the diseases of which they are the consequence. They result from that property common to all nerve tubes which, injured at one point of their course, become altered throughout all that portion which has thus lost its relations to the parts from which they take their origin, and which exert a preponderant influence on their nutrition. |