than morphia. In slight cases relief may be afforded by belladonna, or by atropia injected beneath the skin. Chloral, or chloral and bromide, or any of the milder sedatives, may be given if there is insomnia. Bromide alone, unfortunately, has very little power to lessen the spinal reflex action. Frequently, the spinal ice-bag is the most effective and least injurious.

When the disease has passed into a chronic stage, iodides have been thought useful. Counter-irritation may be employed freely with advantage. Tonics, iron, quinine, and even strychnia are beneficial. Warm baths, as those of Bath and Aix-les-Bains, seem sometimes of service, especially employed as hot douches to the spine. But the acute form is followed by a tendency to the slow subsidence of its effects, which makes the influence of such measures difficult to estimate. The local consequences, muscular atrophy, contracture, &c., need special local treatment by electricity, rubbing, and the like.

Epidemic cerebro-spinal meningitis is described in the section on diseases of the cerebral membranes.

CHRONIC INTERNAL MENINGITIS,

Chronic inflammation of the membranes of the cord, within the dura-matral sheath, is divided into two forms, according as it begins in, and chiefly affects, the dura mater, chronic internal pachymeningitis, or the pia mater and arachnoid, chronic leptomeningitis. Although these forms sometimes present distinct clinical and pathological features, they have, when of considerable degree, many characters in common; they own the same causes, and need the same treatment. Hence it is most convenient to describe them together as forms of internal meningitis. The condition termed hæmatoma of the dura mater depends on a form of hæmorrhagic inflammation.

Chronic meningitis is seldom fatal, and is rare as a general and primary malady. As such, therefore, our knowledge of it is still scanty, and the opinions formerly current have had to be largely curtailed. It was inferred that chronic symptoms, analogous to those which, when acute, are due to acute meningitis, were evidence of a chronic form. This was, therefore, assumed to be the cause of a group of symptoms, of which spasm is the prominent and dominant feature, which are now known to be due solely to a morbid state of the spinal cord itself, and to be consistent with a perfectly normal state of the membranes. Hence "chronic meningitis," as it was recognised twenty years ago, as a "clinical entity," has ceased to exist, or rather has passed into the pathological conception of "primary lateral sclerosis." The definite knowledge we now have of general primary chronic meningitis is limited. The important fact regarding it is that its symptoms differ from those of the acute form more widely, perhaps, than do those of any other chronic inflammation. Yet this

difference depends on a comparatively small element-on the fact that only acute inflammation causes acute irritation of the motor and reflex structures. The chronic form may irritate the sensory nerve-roots, but its motor manifestations are chiefly the result of pressure, and even to this much of the pain may be due. The pressure may cause spasm, but it is a slow tonic contraction, wholly unlike that of the acute form. The difference in the effect of the two forms of inflammation suggests many problems that deserve investigation, but their consideration would be out of place here.

CAUSES.-Chronic internal meningitis, in every form, is most frequent in adult age, and, like acute inflammation, affects men more frequently than women. In its general and primary form, it has been thought to occur more readily in persons with neurotic heredity, although the influence of this is doubtful. Debilitating influences of various kinds predispose to the disease, and prolonged over-exertion has been thought sometimes to produce it. Among exciting causes the most important is severe and repeated exposure to cold. Traumatic lesions, concussion, &c., are occasional causes. It may result by extension from inflammation outside the dura mater and from chronic inflammation of the substance of the cord itself. But their influence in producing chronic internal inflammation (except as a sequel to the acute form) is a subject on which the opinions of the past have still to be subjected to careful comparison with ascertained facts. It is probable, however, that the condition does sometimes follow concussion of the spine that has no immediate or acute consequences, and the chronic stage into which an acute traumatic meningitis subsides may last so long as to throw its initial form into the shade, and may not only persist with independent pertinacity, but may extend without relation to the original seat. Thus we must distinguish as effects of injury, the local and the general forms. The latter are predisposed to by the influences that seem to facilitate the occurrence of the primary form, and in these cases the influence of the injury often seems to be trifling, and the existence of the morbid state is not always beyond doubt.

Local chronic meningitis may also result from any chronic disease either of the membranes themselves, the bones, or the spinal cord. These need not be enumerated in detail. It occurs in all cases of compression, and especially in all forms of chronic myelitis that involve the superficial layers of the cord.

Lastly, certain general morbid states are frequent causes. The first is alcoholism, which may give rise to general inflammation, involving both the pia arachnoid and the superficial layers of the cord in various degrees. A second and also common cause is syphilis, which may produce either pachymeningitis, surrounding the cord in the way presently to be described, or local leptomeningitis, irregular in position and in effects. Lastly, in very rare cases, tubercle has given rise to a chronic inflammation, chiefly of the inner surface of the

dura mater. Hæmorrhagic pachy meningitis occurs especially in the insane, but has been met with as a consequence of chronic alcoholism and after injuries.

PATHOLOGICAL ANATOMY.-In slight and moderate degree, there is merely opacity and thickening of the membranes affected, sometimes with distension of vessels or minute spots of extravasation. The opacity of the arachnoid may be such that the spinal cord cannot be seen through it. The inner surface of the dura mater may be granular when it is not otherwise changed. The spinal fluid is increased in quantity and is turbid. When the changes are greater

in degree, the dura mater and pia mater may be connected together by a layer of inflammatory tissue of considerable thickness, so that it may be impossible to say in which membrane the disease commenced. The microscope shows the ordinary elements which result from inflammation, cells of various kinds, many lymphoid and pus-like corpuscles, and distended vessels, often incrusted by similar cells. Frequently also the pia mater is transformed into a thick irregular layer of homogeneous tissue in which no distinct cell-elements can be

FIG. 92.-Chronic alcoholic meningitis. Section of edge of anterior column and of a large nerve-root; carmine preparation. p. m., pia mater irregularly thickene and transformed into amorphous-looking tissue, from which wedge-shaped branching tracts (xx) extend into the white substance; f.f., fasciculi of nervefibres entering the cord; a., an artery in the nerve-root, enlarged and with thickened walls; t. t., tracts of amorphous connective tissue; e., a small extravasation.

perceived, and only faint indications of a fibrous structure (Fig. 92). The walls of its vessels may be greatly thickened by similar material. The nerve-roots passing through the diseased membranes very seldom escape, as they may in the acute form, but are inflamed,

reddened, and swollen in the active stage, and afterwards compressed and atrophied, if the amount of new tissue formed about them is considerable. The fibres suffer especially when the inflammation involves the dura mater, on account of the unyielding character of the fibrous sheaths which the nerves receive from that membrane. When the pia mater is thickened, scattered tracts of connective tissue may be seen in the substance of the nerve-roots, between the fibres (Fig. 92, t).

The spinal cord presents the same variations in the degree in which it suffers. It may be little affected, but is frequently damaged by the extension to it of the inflammation of the pia mater, which causes softening, vascularity, loss of distinction between grey and white substance, breaking down of nerve-elements, and infiltration by lymphoid and other inflammatory cells. Ultimately indurating tissue remains, constituting an irregular zone of peripheral sclerosis. From the thickened pia mater tracts of similar tissue may extend into the cord, becoming narrower as they pass inwards and sending out branching trabeculæ (Fig. 92, x). Between these tracts the nervefibres are more or less damaged, partly by the inflammation, and partly by the compression produced by the newly-formed tissue.

This peripheral sclerosis associated with chronic meningitis, espe cially in the neighbourhood of injuries, frequently damages tracts that undergo secondary ascending degeneration-post-median column, direct cerebellar tract, and ascending antero-lateral tract. The result is to produce a mixed lesion, the precise nature of which is not always easily distinguished and has certainly often been mistaken. The equivocal aspect of the process is probably increased by the fact that, as we have seen, secondary degeneration entails an interstitial process that is prone to assume an inflammatory character, espe cially when set up by an irritative lesion. Hence the peripheral sclerosis set up by the meningitis is apt to carry with it a certain amount of inflammation in the pia mater far beyond the region to which this would otherwise be limited. A similar thickening of the pia mater is, however, met with over areas of the cord that are the seat of other forms of sclerosis, both those that are systemic, as in tabes, and those that are random, as the insular form. It is probably secondary in all cases, but it formerly gave rise to some erroneous conceptions of the nature of such degenerations (see Locomotor Ataxy). A still more considerable implication of the pia mater is met with over regions that are the seat of focal chronic myelitis.

In the ordinary form of chronic meningitis, the membrane in which. the inflammation begins may be much more affected than the other, although the latter is very rarely healthy, except in the slightest cases. Inflammation beginning in the pia mater and arachnoid is often extensive in range, and may be considerable or slight in degree. That which commences on the inner surface of the dura mater is frequently limited in extent, but is accompanied by the formation of a large

amount of new tissue, and hence has been termed hypertrophic internal pachymeningitis. It constitutes a very important variety, giving rise to peculiar and grave symptoms which were first carefully studied by Charcot and Joffroy. It is most commonly the cervical region, but sometimes occurs at the lower part of the cord. On opening the spinal canal a fusiform tumour is seen, the outer surface of which is the unaltered outer surface of the dura mater, and on section the enlargement is seen to depend chiefly on a great thickening of the inner part of this membrane, sometimes amounting to a quarter of an inch; several layers of new tissue can often be distinguished. The pia mater may be normal, but is more commonly thickened, and it is often united by the thickened arachnoid to the tissue proceeding from the dura mater. The cord is compressed and commonly softened at the spot, and it presents signs of inflammation. The nerve-roots are also damaged and compressed by the newly-formed tissue. Sometimes at the spot most affected, the cord may be surrounded by a ring of new tissue of cartilaginous hardness. In other cases the thickening of the dura mater is slighter and more diffuse, affecting occasionally a wide extent of the membrane. In rare cases the membranes about the cauda equina may alone be affected-the dura and pia mater adherent, and the nerves united in a fibrous mass.

The white fibroid or cartilaginous plates found so often in the arachnoid after death are probably not connected with preceding inflammation. In most cases in which they are found, no symptoms have existed during life. It is said, however, that when they are numerous and extensive they may give rise to symptoms closely resembling those of chronic meningitis (Vulpian). But fibroid plates in the dura mater have been seen in a case in which previous symptoms suggested that they resulted from chronic inflammation (Jaccoud).

The rare condition termed internal hæmorrhagic pachymeningitis, or hæmatoma of the spinal dura mater, is similar to, and commonly associated with, that which affects the cranial membrane, and will be afterwards described. In this, a reddish-brown exudation covers the surface of the membrane, and is composed of fibrin and extravasated blood; the latter may be encysted in small cavities, or may be in various stages of transformation. The change commonly extends over a great part of the dura mater, and is apparently the result of hæmorrhage into inflammatory tissue.

The local form of syphilitic meningitis presents an irregular thickening of the pia mater and arachnoid, with the extensive production of new tissue in the affected region characteristic of this variety, so that it often resembles a diffuse growth as much as a chronic inflammation. The new tissue has a peculiar gluey aspect, and presents a tendency to caseous degeneration and fibroid change, so that scattered or coalescing cheesy spots are ultimately met with in tracts of mixed fibrous and gelatinous aspect, the later predominating in the more