1. Diseases Of Texture

1. Congestion, Apoplexy

The anatomical characters of this congestion are too evident to require description. The subjects of it are mostly those in the tenderest childhood; infants just born or suckling, and individuals in the years of growth. In the former, the congestion generally involves the pia mater of the whole spinal cord, and that of the brain also; in the latter, on the contrary, it is generally habitual, and confined to the lumbar region of the cord, and is combined with distension of the sinuses in the vertebral canal, and with congestion - so-called hemorrhoidal congestion - of all the pelvic organs.

When the congestion is excessive, it becomes fatal as vascular apoplexy; but sometimes that termination is anticipated by the occurrence of hemorrhage into the sac of the arachnoid (apoplexia gravis). A quantity of blood, most of it loosely clotted, is then found filling the sac, sometimes even up to the medulla oblongata. This is observed especially in the individuals first named.

Amongst the results of spinal congestion, acute and chronic effusions of serum into the arachnoid sac may be noticed. The former, the acute, constitute serous spinal apoplexy, which also occurs mostly in children. The serum is generally of a yellowish color, or yellowish tinged with red, and after it is effused, the vessels still remain overfilled. The chronic effusion consists of colorless clear serum. Opacity, thickening, or ossification of the arachnoid coexist with them, and dilatation of the sac in the lumbar region: congestion is not necessarily present with the chronic effusion, though there is abundant evidence in the dilatation and varicose state of the vessels of the pia mater, and in the condition of the arachnoid before mentioned, of its previous repeated occurrence.

The chronic effusions so common in advanced age, are, in part at least, consequences of the congestions brought on by atrophy of the medulla and nerves.

2. Inflammation (Meningitis Spinalis)

Inflammation of the pia mater of the spinal cord succeeds various internal injuries; and it may pass over to the membrane from adjoining inflamed tissues: but, besides being thus set up, it sometimes, though very rarely in comparison with cerebral meningitis, comes on spontaneously. It is very often combined with cerebral meningitis, and occupies the whole spinal cord; and it is a disease particularly frequent in early childhood (Billard). The characters of the inflammation are the same as those of cerebral meningitis, but there are several peculiarities about the exudation.

The greatest part, and even the whole, of the product of the inflammation may be poured out upon the surface of the pia mater, into the inner sac of the arachnoid: one layer of it then hangs loosely on the cord, enveloping especially its posterior part; while another and still larger portion, mixed with more or less serum, is accumulated in the arachnoid sac, especially behind the medulla. The pia mater is rendered slightly turbid, and is swollen by the serous portion of the exudation, but its tissue contains very little plastic product, and that little but rarely. The cord generally appears pale and anaemic, and occasionally its texture is somewhat loosened and softened by symptomatic oedema (serous infiltration). The explanation of these appearances is found, on the one hand, in the peculiar relation which I remarked at the commencement, as subsisting between the spinal arachnoid and pia mater; and, on the other, in the density of the structure of the pia mater, and the closeness with which it adheres to the medulla.

The exudation is usually of a pure yellow, or greenish-yellow color, coagulable, fibrinous, or purulent. I have never had occasion to suspect it to be of tuberculous nature: and this observation accords with the facts, that spontaneous spinal meningitis so commonly coexists with that form of cerebral meningitis which produces similar exudations, and that tubercle of every kind is extremely rare in the pia mater of the cord. An acute tuberculosis, indeed, so far as I am aware, never takes place in it.

3. Adventitious Growths

They are all, as I have remarked about tubercle, extremely rare. Ollivier mentions a case of encephaloid, which formed a layer, adhering to the posterior part of the pia mater, from one end of the cord to the other.