The following case is related by Cruveilhier. A young amaurotic girl, paraplegic of move ment only, died from some unknown cause. The spinal cord presented on its posterior sur face in its entire leng-th a large reddish-grey (gris-rose) column, formed by the posterior columns. All the rest of the cord was per fectly healthy.
In a case recorded by Dr. Wm. Budd it is stated that the lower extremities were quite deprived of motion, " but with sensation un affected." The disease was the result of a severe blow on the back from the boom of a ship, which led to a curvature of the spine, formed by prominence of the dorsal vertebrae from the fourth to the ninth inclusive. After death a portion of the cord, about two inches in length, corresponding to the curvature, was found softened in the posterior columns. The tissue was not diffluent, but became flaky and partially dissolved when a small and gentle current of water was poured on it. In this case, no more than in that of Air. Stanley, the lesion was not enough to destroy sensation, but surely it was sufficient to impair it, if the posterior columns are to be regarded as the channels of sensation." Serres records the case of a woman who had been paraplegic for two months: sensibility was preserved in the lower extremities; the lesion consisted in disease of the posterior columns of the cord below the middle of the dorsal region.-I In two cases which occurred in King's Col lege liospital under my own care, the promi nent symptom was impairment of the motor power, without injury to the sensitive; yet the seat of organic lesion in both was in the pos terior columns of the cord.
Nasse,in the paper before referred to, alludes to several cases of the same nature, in which disease affected the posterior columns, but did not impair sensation.
Longet, who is a warm advocate for the identity of function between the posterior roots and posterior columns, cites some instances in which total loss of sensibility coexisted with degeneration of the posterior columns as the only lesion; in these cases, however, the pos terior roots of the nerves were involved in the disease, and their function became impaired or destroyed in consequence. A oase of this kind, to be conclusive upon the point in ques tion, ought to exhibit complete destruction of the posterior columns, or of a considerable portion of them, with perfect integrity of the posterior roots and of the antero-lateral co lumns. If in such a case there were total loss
of sensibility in the parts in nervous communi cation with the diseased portion of the spinal cord, then, indeed, we would be justified in affirming that the antero-lateral columns took no part in propagating sensitive impressions, and that the loss of sensibility was due to the morbid state of the posterior columns.
When to these results, obtained from patho logical researches, we add those of experiment, nothing is gained which can be favourable to the attribute of sensitive power to the posterior columns of the cord. Dr. Baly's experiments on tortoises showed that movements might be excited whether the anterior or the posterior columns were irritated, much stronger mo tions being excited hy the posterior than by the anterior columns. Longet found that mo tions might be excited by irritation of the posterior columns of the cord if the experiment had been made immediately after the transverse division of the cord, and he refers such mo tions, probably with justice, to an excited state of the cord. After a little time this subsides, and then M. Longet was able to pass the galvanic current through each or both of the posterior columns, without exciting any mo tions when the lower segment of the cord was acted upon, but causing pain, as evinced by loud cries and writhing of the body, when the upper segment was tried. From experiments of this kind no satisfactory deductions can be made : to irritate the posterior columns of the spinal cord in a living dog without affecting in some degree the posterior roots of the nerves, appears to me to be quite impossible, even in the hands of the most practised vivisector.
Neither anatomy, pathological observation, nor experiment, lend sufficient countenance to the doctrine of the identity of the function of the posterior roots and posterior columns to jus tify us in concluding, that these columns are the ordinary channels for the transmission of the sensitive impressions made upon the trunk and extremities.