81 In the latest treatise on nervous diseases published in our language (Ross, loc. cit., vol. ii. p. 325) the insufficient foundation on which a whole chapter has been built up is illustrated by the admission that the usual evidence of acute central myelitis may be observed far beyond the limits of the hemorrhagic infiltration. If a large area of softening in the brain were found to contain a central or peripheral clot of blood, and histologically resembling a typical embolic or thrombic softening, no one would be in doubt as to which of the two was the primary lesion.
Embolisms and embolic softenings of that part of the spinal cord which is supplied by the small spinal vessels are so rarely observed in the dead-house that our knowledge of their possible occurrence and character is almost entirely the result of experimental observations or based on analogy. The situation of these vessels, the angle at which their supply-tubes are given off from the aorta, all act as protectors of the cord against what is one of the chief dangers to which the brain is exposed. No definite symptoms have been attributed to the few doubtful cases of simple embolic occlusion of the spinal arteries found accidentally in human subjects. Even those emboli which, when once let loose in the circulation, are found distributed in nearly every organ of the body, those derived from ulcerative endocarditis and those due to the invasion of micrococci, are comparatively rare in the cord. Leyden found multiple capillary emboli in the spinal cord from the former cause. Small grayish white foci in a similar distribution were found to be due to an invasion of cocco-bacteria from a decubitus by Rovigli.82 In this latter case an increase of pain and muscular spasm in the history of the case of sclerosis which was thus complicated was attributed to the parasitic affection.
82 Rivista sperimentale di Freniatria, 1884, x. p. 227.
Just as simple and infectious embolic lesions are frequent in the brain and rare in the cord, so purulent inflammation or abscess is an exceptional occurrence in spinal as compared with cerebral pathology, and probably for the same reasons.
Simple Acute Myelitis.
SYNONYMS.—Spontane (primäre) acute Rückenmarkserweichung, Softening of the spinal cord, Ramollissement blanc de la moelle, Myélite aiguë.
As Leyden, whose treatise83 may be regarded as the foundation of our knowledge on this subject, correctly avers, it is to Abercrombie and Ollivier that we owe the determination of the existence of that acute structural disease of the spinal cord, now termed myelitis, as an affection independent of meningeal changes. The anatomical descriptions given by these older writers may be accepted at the present day as models of accurate observation by the naked eye. Their statement that in acute myelitis the substance of the spinal cord is softened and changed into a puriform, yellowish, diffluent mass; that while the disorganization is sometimes more marked in the posterior, at others in the anterior, and occasionally in the lateral half, it is most pronounced in the axis of the cord, because the central gray substance is the favorite starting-point of the morbid process,—requires no modification to-day. Considerable doubt existed in the minds of the contemporaries of Ollivier and Abercrombie as to whether this change was the result of a true inflammation; and one of the clearest thinkers of the day, Recamier,84 regarded myelitic softening as a lesion peculiar to the nervous apparatus, and different from ordinary inflammation. I believe that the most profound investigators of the present day have not been able to rid themselves of a similar doubt. The discovery of Gluge's so-called inflammatory corpuscles, which was regarded as settling the question, only served to confuse the student by the confidence with which it was urged that they were infallible criteria of the inflammatory process. Under the non-committal designation of granule-cells these bodies still flourish in the annals of cerebro-spinal pathology. As we shall see, a number of products of real disease, of artifice, and of cadaverous change have passed and do pass muster under this name. The first substantial progress in our knowledge of the minute processes underlying inflammation of the spinal cord was made by Frommann and Mannkopf, but it applied altogether to the chronic inflammatory or cirrhotic affections of the cord. The difference between acute and chronic myelitis is greater than is the difference between acute and chronic inflammation in any other organ; and it must be admitted that if Recamier is to be regarded as having erred in asserting that acute myelitis is not a true inflammation, he is justified in so far as he asserted many features of the process to be altogether peculiar to the organ affected. Leyden himself attempted to throw light on the subject by provoking myelitis experimentally in dogs. He injected Fowler's solution into the spinal cords of three dogs, and in each instance produced changes which he interpreted as comparable to the myelitis of human pathology. But the inflammation thus provoked was not of the cord-substance alone; it also involved the membranes, and the inflammatory foci were in several instances purulent. Now, pus never85 forms in ordinary myelitis. An abscess of the cord never occurs where a septic agency can be excluded. In six dogs whose spinal cords I wounded in the dorsal and lumbar regions by aseptic methods, and who survived from two to seven days, I never found purulent or indeed any active inflammatory process, as that term is ordinarily understood, but exactly such passive and necrotic or reactive changes as occur in the acute myelitis of human pathology.
83 Klinik der Rückenmarkskrankheiten, ii. p. 115.
84 Cited by Leyden.
85 In the textbooks and encylopædias, without an exception, the statement that pus may be a product of myelitis is made. This is true of traumatic cases and of such depending on septic and zymotic causes alone. I am unable to find a single carefully observed case of the occurrence of pus in simple myelitis in the literature.