Finally, a typhoid state may set in or a pyæmia occur, when the discharges may become involuntary or unconscious, and brain symptoms—insomnia, stupor, delirium, and coma—supervene; or the patient may linger long enough to perish by simple exhaustion or marasmus.
Under favorable hygiene the great majority of cases of catarrhal dysentery recover without special treatment in the course of from three to ten days, but specific dysentery has no definite duration and but little tendency to spontaneous cure. The worst cases are often quickly controlled by appropriate interference, and the most surprising results may be sometimes obtained in cases of even years' duration. On the other hand, a certain percentage of cases is characterized by a defiance to every kind of treatment, including the last resort, a change of climate.
An acute case of catarrhal dysentery generally subsides without lesions, and the natural duration of the attack may be much abbreviated by proper treatment. Specific or epidemic dysentery lasts from two to four weeks, or, becoming chronic, continues for years or for life, with exacerbations and remissions.
Various complications are liable to occur in the course of the disease. Three deserve especial mention—viz. affection of the joints (rheumatism), paralysis, and abscess of the liver. Perforation and peritonitis, always possibilities, and deformities of the colon, thickenings, and constrictions, are not infrequently left.
MORBID ANATOMY.—The lesions of dysentery are the ordinary signs of inflammation of a mucous membrane and its subjacent structures. They do not differ in any essential way from those of any mucous surface in a state of inflammation, the minor variations being due to differences in the anatomy and physiology of the part affected. Thus, a description of the pathological process in inflammation of the pharynx, bronchi, or uterus would answer upon the post-mortem table for the same process in the large intestine, and the finer microscopic lesions could be differentiated in any case only by the histology of the part affected.
A slight lesion of any mucous membrane constitutes what is known as a catarrhal process; a more grave affection, a diphtheritic process; a more chronic inflammation, a hypertrophic or hyperplastic process. Hence an easy distinction between sporadic and epidemic cases might be based upon the character of the lesion found. But, as has been stated already, it is impossible to draw a line between catarrhal and specific cases, the same lesions being found in either form. The difference, so far as the morbid anatomy is concerned, is wholly in degree or stage, and not at all in kind, the specific (epidemic) form presenting the graver lesion as a rule. So most cases of sporadic dysentery show only catarrhal lesions, while most cases of epidemic dysentery show diphtheritic lesions.
Catarrhal dysentery shows as its first obvious alteration a hyperæmia of the mucous surface. It is limited exclusively to the large intestine in the vast majority of cases, and only in rare exceptions affects the small intestine, though cases have been mentioned as curiosities in which the process has reached the stomach in its upmost prolongation. The hyperæmia is most marked, as a rule, in the lowest parts of the large intestine, the rectum and descending colon, but there is, as Virchow has pointed out, a peculiar predisposition to affection at the seat of all the flexures, the iliac, hepatic, splenic, sigmoid, where the additional element of fecal arrest or impaction is superadded to the cause of the disease.
The catarrhal process occurs first in detached spots or streaks upon the projecting folds or duplicatures of the mucous membrane; which spots coalesce to form extensive surfaces. Examined by transmitted light, these surfaces show a distinct arborescence of the vessels. Or the disease may commence in the follicles in distinct areas of the large intestine, and may remain confined to these structures to constitute the variety known as follicular dysentery.
The hyperæmia of inflammation is attended with dilatation and paresis of the vessel-walls and retardation of the circulation. The whole process may be arrested at this stage, so that there escapes from the vessels, at most, only serum to develop the oedema which, with the defective nutrition from arrest of the circulation, gives rise to the softening of the epithelial cells. These cells may be thus lifted from their bed to constitute the process of desquamation, the fundamental anatomical characteristic of acute dysentery, by which process the submucous connective tissue is laid bare and the so-called catarrhal ulcer results. Or the epithelium, but partially detached, may remain upon the surface, "either raised in the shape of small vesicles which contain clear serum, or it forms a grayish-white layer resembling the mealy scurf of the epidermis—an appearance which probably induced Linnæus to term dysentery scabies intestinorum interna" (Rokitansky).
Kelsch maintains that the inflammatory process in dysentery commences in the delicate connective tissue between the follicles, the network of small spindle-shaped cells with multiple nuclei becoming speedily penetrated by a number of very small, newly-formed vessels. Where the epithelium is desquamated the surface is covered with granulations as after a wound. The disposition of the follicles is soon deranged, for, instead of standing in rows like gun-barrels, they are pushed asunder and uplifted, so as to remain at different heights. Their interior becomes blocked with mucus or their orifices occluded, so that retention-cysts are formed to give rise to the appearance of the bead necklace. Soon the walls of neighboring follicles coalesce, dissolve away, and communication is established between them. The interior of these communicating tubes or canals is filled with vitreous mucus; the walls are stripped of their lining cells, but their "blind extremities contain still adherent colossal epithelial cells." Moreover, the follicles break into each other under the proliferative budding process, so that the end of a distorted tube may be found in the interior of another. Where follicles are destroyed the mucous membrane above them or in their vicinity collapses—a condition observed and described by Colin as effrondement. The mucosa in these regions may appear perfectly uninjured, but by "blowing upon it with a tube it is lifted up like an ampulla to show an opening in its centre," though more frequently the mucous membrane collapses or sinks in at the region of destruction. The inner surface of the mucosa is rendered additionally uneven by the elevations or protuberances caused by the proliferations in the submucous connective tissue. The older writers (Pringle, Hewson) regarded these projections as tumors of the mucosa, and Rokitansky, who describes their true nature, speaks of them as warty, tubercular (nodular) swellings or fungoid excrescences—constituting a condition, he says, which Gély has termed hypertrophie mamelonné. The alternate elevations and depressions thus produced have been likened to the representations of bird's-eye views of mountain-chains.