Microscopic Lesions.—In striking contrast with this paucity of macroscopic lesions are the interesting structural changes revealed under the microscope. These lesions are usually comprised within circumscribed foci whose size may vary from a long diameter of 2 mm.96 to one of from 10 to 30 mm.97 Sometimes bilateral foci are found with monoplegic paralysis; thus one side or the other preponderates in the morbid process.
96 Case Roth, Tab. V.
97 Case Schulze, Tab. V.
In recent cases (Damaschino's, at twenty-six days; Roger's, at two months; Turner's, at six weeks) patches of red softening existed at the portions of the cord containing the nuclei of origin of the paralyzed nerves. In Turner's case the focus contained hemorrhagic extravasation, and the traces of this were clearly perceptible in Roger's first case. The blood-vessels are dilated; their lymphatic sheaths infiltrated with leucocytes and with granular corpuscles; their walls are thickened, pigmented, or fatty.
Leucocytes are often disseminated through the diseased area, and in one case (Demme) were accumulated into a focus of pus. Besides the leucocytes, the foci are often infiltrated with large round granular cells that seem to be transformed neuroglia-cells (Leyden). In one case neuroglia nuclei were accumulated in a ring around the focus, seeming to indicate the beginning of encapsulation.
The most striking lesion, however, and the one which is common to the most recent as well as to old cases, is the deformation, atrophy, and final disappearance of the large ganglionic cells of the anterior cornua. The first change consists in granular pigmentation;98 then the prolongations disappear, leaving the body of the cell shrunken and deformed; at last the whole cell disappears. Sometimes all the cells of an anterior horn have disappeared throughout the entire depth of the focus; quite as often, in certain sections at least, the atrophy is limited to certain groups, as the external,99 or the external in one focus, the antero-lateral in another, situated on the opposite side of the cord.100
98 Case of Echeverria, Tab. V.
99 Case by Schultze (this is a case of ancient lesion), Tab. V. (Virch. Arch., Bd. lviii.).
100 Case by Taylor, Tab. IV. (Path. Trans., London, 1879.)