In hypertrophy, the cord is enlarged and looks full and plump, without any alteration of its consistence or of its intimate structure. It is not improbable that the elementary fibres as well as the vesicles of grey matter may be en larged in such cases, and that the increased dimensions of the whole organ must be attri buted to this cause, and not to the deposition of any new material in it. I have not, however. had any opportunity of ascertaining this point by microscopic exarnination.
Atrophy occurs in the cord generally as the result of some local pressure from a tumour developed in connection with some one of the membranes or external to them. In a case of this kind which I lately examined, the tumour consisted of a mass of scrofulous matter situate between the vertebne and the dura 'pater in the upper part of the dorsal region. That part of the cord which was pressed upon by the tumour was wasted to one-half its natural size, whilst below it the cord exhibited its natural size.
Atrophy of the cord occurs as part of that geneml wasting of the nervous centres which accompanies advanced life, or a state of general cachexy. In persons long bedridden the cord is found in a wasted state ; and in cases of "ex tensive hysterical pamlysis, in which exercise of the enfeebled limbs has been neglected, the cord will participate in the w-asting of the nerves which supply the affected parts.
Induration of the cord is not of unfrequent occurrence, and appears to be the result of some abnormal nutrition analogous to if not identical with chronic inflammation— inflam mation modified, perhaps, in the nature of its event by some peculiar state of the blood. The hardness occurs generally in patches, involving more or less of the thickness of the cord, and affecting the peripheral parts of the body, in pro portion as it involves the immediate points of implantation of the roots of the nerves, or those roots theniselves. It is generally accompanied by some discolouration of a light brownish hue, as if the first changes which gave rise to it were attended with extravasation of the colouring matter of the blood.
Sometimes, however, induration seems to re sult from the changes which accompany atro phy of the cord, as if frotn an imperfect sup ply of the fluids necessary for perfect nutrition.
Softening of the cord is found in two states, which are probably essentially different in thcir intrinsic nature and origin. One is that of red
softening; the other is that of white or colourle softening. In the former the tissue of spinal cord is much softer than it ought to and is readily disintegrated by a stream water directed upon it ; its colour is due to full injection of the bloodvessels which verse it, or to some extravasated blood. In latter the nervous matter is reduced to a semifluid mass, like thick cream, without least appearance of injected vessels. In former the nerve fibres are more or less brok down and softened; in the latter there is little or no breaking down of the fibre_s, but theyare at-, tenuated and have lost the distinctive characters of the white substance and central axis to a greater or less deg,ree. Red softening appears to be in-j flammatory in its origin, but white softening in dicates a deficient supply of blood, and so far resembles the gangrene which occurs in external soft pasts.
The anatomist should be prepared to distin guish the white softenin,g, which is the product of a morbid process durino. life, from that which occurs after death as the result of decom position, or which may be produced by violent compression of a part of the cord in opening the spinal canal. The softening which results from decomposition, in general, occupies the greatest part of the cord or the whole of it, and does not exhibit so pure a white colour as the morbid softening. It sometimes has a. greenish or a dusky hue, and is more or less fcetid. The softening from injury is very circumscribed, and is surrounded by nervous matter perfectly healthy in colour and consistence. There is, moreover, generally evidence of injury to and rupture of the pia mater, the softened matter of the cord protruding through the rent in this membrane. Where the softening is morbid, it wants the abruptness which occurs in the latter case, and the diseased part gradually passes into healthy structure.
The inflammatory softening is sometimes infiltrated with purulent matter, which, if not recognizable by the naked eye, may be easily detected by the microscope and by reagents. In rare cases the pus is collected into a circum scribed abscess, occupying more or less of the thickness of the cord.