In rheumatism, again, something very like metastasis to the heart occurs, and, therefore, there may be something like metastasis to the brain; the dis ease is essentially erratic. But in by far the larger number of cases we are sure that the delirium does not depend on metastasis, because rheumatic in flamniation of the joints, of the heart, and of the pleura, is accompanied by exudation of lymph, and rheumatic inflammation of the membranes of the brain should be similarly evidenced by the presence of lymph. Post-mortem examinations prove that this is very rare indeed ; and we are, therefore, jus tified in assuming that, unless the evidence of inflammation within the cra nium derived from other sources be very decided, delirium, following upon or accompanying acute rheumatism, is to be classed along with that of fever, of pneumonia, of erysipelas, and to be taken merely as evidence of blood-poison ing; and this so much the more certainly if there be no retrocession of the affection of the joints, or if it have been preceded by inflammation of the heart.
In one of the less acute forms of rheumatism, the synovial membrane is distended with serum, not with lymph, and several cases are on record in which the sudden disappearance of the effusion in the joint has been followed by an equally sudden occurrence of effusion in the brain. In these cases the symptoms were rather of coma or stupor than delirium; they, perhaps, are the only real instances of metastasis met with in practice.
e. Delirium, when not symptomatic of disease in the blood, or in other organs acting through the blood, must be taken as indicative of changes going on within the cranium. It will be best first to consider that condition which is linked with the tuber cular diathesis, in order that, by a process of exclusion, we may arrive at those which are uncomplicated. The association be tween tubercles and inflammation of the brain was first clearly recognized in what is called the acute hydrocephalus of child hood; it is not necessary that actual deposit of scrofulous matter within the cranium should take place, though it be frequently found there after death. Delirium is by no means a constant accompaniment of hydrocephalus; in fact, in early childhood, before the reasoning powers are developed, it is not only difficult to take cognizance of such a state, but experience teaches that the disturbance is more likely to be manifested by convulsions than by mental phenomena.
The association, however, is not limited to childhood ; in youth, or even in adult age, the same condition of inflammation accom panies the tubercular diathesis, and must be presumed to spring from it. Here, delirium is one of the earliest symptoms of the disease ; its character sometimes resembles that of fever, and then the diagnosis is extremely difficult, because all the general symp toms of fever are present ; the pulse is quick, the skin hot, the tongue coated, and the bowels relaxed ; like fever, the tubercular diathesis is apt to be associated with diarrhoea, ending in ulcera tion ; as in fever, too, the pulse is essentially weak, and tends to be rapid ; it is only distinguished by its great variableness. Pain
in the head is more constant, there is often much heat externally, and the delirium is more pronounced and more constant ; in its commencement it is not so distinctly a nocturnal state with total remission by day as in fever, and it is generally developed earlier in the disease. Such circumstances must at least lead to inquiry whether there be any evidence of tubercle. • The delirium sometimes assumes quite a different form;' it is such as has been called passive delirium; there is scarcely any talking or restlessness ; the patient lies in a partially unconscious state, taking little note of surrounding objects ; confused in his ideas, answering either not at all, or in a very unintelligible man ner, any question put to him, and unable correctly to describe his condition or his sensations ; he passes his urine and feces invol untarily, and is with great difficulty induced to put out his tongue and to take his food or his medicine ; the tongue is less generally coated, sometimes tolerably clean, occasionally unnaturally raw and glazed.
In the further progress of the disease, symptoms of pressure on the brain develop themselves in either case ; there is dilatation of the pupil, and the supervention of coma, not from sheer exhaus tion, but as the effect of active effusion.
The history of the case generally records ill health of some standing ; the more acute attack has been insidious ; the febrile symptoms have not set in suddenly with rigor and general de pression ; there has been marked pain of the head and delirium, as a very early symptom. It is to be remembered that we are not now speaking of the diagnosis of scrofulous inflammation, but of the delirium occasionally accompanying it, which is especially seen in youth and adult age : in such cases this mode of incursion is the usual one, though the disease may also set in, as it does more frequently in childhood, by severe vomiting and constipation, or by convulsions. As it is in the lungs that we can most surely trace the development of tubercle, it is to these organs that we must especially look for aid in our diagnosis ; the condition of the abdominal viscera must also be inquired into ; and we note the occurrence of htemoptysis, or the liability to diarrhoea, as important features in the narrative of the case.