"The neuroglia of the anterior cornua is increased in amount; the vessels appear shrunken, with thickened walls and large perivascular lymph-spaces.
"In the lumbar cord the cells in the anterior cornua appear normal: in this respect the lumbar cord is in marked contrast with the cervical."
23 Loc. cit.
Another class of cases recorded by Gull,24 Schueppel and Grimm, Hallopeau and Westphal, consist in dilatation of the central spinal canal with more or less complete destruction of the gray substance, and in Grimm's case hyperplasia of the connective tissue in the white substance along with increase of the axis-cylinders. The nerve-roots were in a state of fatty degeneration, especially the finer fibres of the anterior roots.
24 Guy's Hospital Reports, 1862.
Still another set of observations discovers a degenerative atrophy of the white columns only of the cord, sometimes the antero-lateral columns and sometimes the posterior. Virchow, Friedreich, and Swarzenski each found typical gray degeneration of the posterior columns, in one instance recognizable by the naked eye. Atrophy of the antero-lateral columns was noted by Frommann and Baudrimont; atrophy of the antero-lateral columns, conjoined with inflammatory changes in the gray substance and atrophy of ganglion-cells, by Duménil; changes in the antero-lateral gray substance and posterior columns by Clarke. Changes have even been found in the posterior cornua and posterior nerve-roots in a few cases, although not confined to them.
Finally, the lesions of this singular disease have been sought also in the sympathetic, and not without some success. Eulenburg's analysis discovered 5 positive observations and 14 negative ones. To the positive must be added the case of Wood and Dercum, who reported a marked increase in the amount of connective tissue and a granular state of the ganglion-cells without diminution in number. Among the changes in the sympathetic were thinning of its trunk and of the two upper ganglia observed by Swarzenski, and advanced fibrous fatty change of the cervical and thoracic portion, with abundant hyperplasia of connective tissue, disappearance of nerve-fibres and regressive metamorphosis of ganglion-cells by Duménil.
PATHOGENY.—We come now to consider the relation of these changes to the muscular atrophy which constitutes the conspicuous symptom of the disease. There are three possible views of the pathology of this affection. According to one, it is a muscular or myopathic disease in the strict sense of the term. Such muscular disease may be primarily inflammatory, a myositis—as Friedreich sought to prove in his great work—followed by fatty metamorphosis of the sarcous substance and subsequent absorption of the fat; or it may be a simple fatty metamorphosis. According to a second view, it is primarily an affection of peripheral nerves or of the anterior roots of the spinal nerves, with secondary muscular atrophy. According to a third, it is a disease of the spinal cord, and more particularly of the anterior cornua of the gray matter—a poliomyelitis anterior.
A careful study of the morbid conditions as described in the various cases reported leads me to adopt the last view. In the first place, the number of instances of positive disease of the spinal cord exceed those of any other seats of alteration, and although the changes do not always involve the anterior cornua, yet it will be noted, from an examination of the foregoing paragraphs, that a decided majority involve either the anterior cornua alone or these in connection with the antero-lateral columns, the number of cases of disease of the antero-lateral columns alone or of the posterior columns and posterior nerve-roots being very limited. Again, the number of instances in which lesions of the anterior cornua are found increases as our means of accurate investigation improve.