Delirium is occasionally associated with acute rheumatism, and we may satisfy ourselves, in the majority of cases, that it is not due to inflammation of the brain, but merely an evidence of deterioration of blood, or of labored circulation, consequent upon inflammation of the heart. It can only cause anxiety when the disease has suddenly receded from the joints, and has not affected the heart ; because, as will be shown when speaking of delirium, we may then possibly have metastasis to the brain. In the chest are to be found the most constant complications of acute rheumatism. By far the larger number of cases of pericarditis which have been recognized during life occur in the progress of this disease, and a considerable proportion of the perma nent valvular lesions may be observed to take their rise in rheumatic endocar ditis or may be traced back, with very great probability, to it. The condition of the heart must, therefore, be watched from day to day ; we must also be prepared for the incursion of pleurisy; and bronchitis sometimes becomes a serious and troublesome complication.
§ 2. Subacute Rheumatism.—When the febrile state is less marked, when the inflammation of the joints is less severe, and the number affected smaller, we have a form of rheumatism which has been called subacute. It may differ in no essential particu lar from acute rheumatism, except in intensity ; in no one symp tom, probably, so much as in the amount of tenderness; there is generally considerable swelling, and, in some instances, a good deal of redness; but the exquisite sensibility of acute rheumatism is wanting. Some of the cases belonging to this class are of short duration, as if they were abortive attacks of the acute form. Some continue for a long period, and take on the characters known as rheumatic gout. Others, on the contrary, present this peculiarity, that the disease is in great measure, or entirely, limited either to onejoint or to a single extremity. The symptoms con nected with the local disturbance may be tolerably severe, but it remains fixed there, and the disease is commonly very obstinate and much prolonged in its duration. Such cases are liable to be taken for simple inflammation of the joint, or synovitis. The best guide in determining their nature is to be found in the his tory of the case. Rheumatism almost always appears in several joints before it becomes located in one; and, on inquiry, perhaps we learn that the patient has had previous attacks of rheumatism or gout. The history of simple inflammation generally points to some accident or injury, acting as the exciting cause, or it tells of syphilis, with nodes or lichenous eruption. The diagnosis is ne cessarily imperfect, inasmuch as both diseases have an inflamma tory character ; and it is remarkable that, in persons of gouty or rheumatic habit, the inflammation, set up by accident or injury, often assumes a specific type, just as we find inflammatory action modified, in other instances, by some peculiar diathesis of the patient, e. g., the scrofulous.
The varieties of subacute rheumatism are chiefly distinguished by the cir cumstance that, in some cases the fibrous structures around the joint, in others the synovial membrane, is the seat of the local inflammatory action. In acute rheumatism the two are more intimately blended; in the subacute form it is not difficult to distinguish the thickening of the ligamentous structures, which are firm and resisting, from the puffy elasticity and feeling of fluctuation com municated by the presence of fluid in the cavity of the joint. The first is more frequently met with in the smaller joints of the wrists and fingers; the other, by far the most frequently, in the knee, where the accumulation of fluid is sometimes very remarkable.
Among the complications of subacute rheumatism gonorrhea& is one of the most important, especially in the male sex. It is a very frequent association of that form in which the swelling and redness seem to indicate very acute action, while the absence of pain and of fever, and the limited nature of the affection, really lead to an opposite conclusion.
A very serious affection of the brain is occasionally seen as a complication of synovial rheumatism, when, during its progress, the sudden absorption of the fluid is followed by delirium and coma.
In subacute rheumatism affections of the lungs and heart are mach less common than in the acute form.
Synovitis is the disease which most nearly resembles subacute rheumatism; and from this, as we have already seen, it can only be distinguished by analys ing the causes of the affection : the local action is the same in each. Other diseases of the joints are more liable to be confounded with chronic rheumatism, under which head their distinguishing characters will be more fully considered.
riere we have only to notice, that in certain cases in which the kneejoint is acted with absolute thickening and degeneration of the synovial mem brane, the external aspect closely resembles that which is produced by the presence of fluid in synovial rheumatism. The history of cases of joint-disease Is generally obscure, and extends over a long period ; their progress is insidi ous, and they are especially distingnished from rheumatic affections by the absence of pain in their commencement. The degeneration of the synovial membrane last alluded to is, indeed, almost painless throughout: its shape sufficiently characterizes it as an affection of the synovial membrane, while the feeling of elasticity and absence of fluctuation show that there is no accu mulation of fluid.