THE RELATION OF RHEUMATISM AND CHOREA.
Of the existence of some relation between rheumatism and chore.a there can be no doubt. The observations of Bright, Begbie, Hughes, Burton, Brown, See, Roger, and others, have placed this beyond question.
Chorea is essentially a disease of the nervous system. Its charac teristic symptom is irregular and uncontrollable muscular twitching and jerking.
For the explanation of such a symptom we turn, not to that part of the nervous centres whose derangement causes delirium, wander ing, and such phenomena as were noted in connection with inflamma tion of the heart, but to that part of them whose function it is to initiate, control, and regulate movement—the motor centres. How the rheumatic constitution leads to disturbance of these centres is the question which we have to solve.
There are two views on this point : one that the choreic symptoms result directly from the disturbing action of the vitiated blood on the nervous centres; the other that they are directly due to a prior affection of the heart—the rheumatic condition acting only indirectly through this.
The former view is that advocated by Begbie. " I cannot help coming to the conclusion that the simple and true view of the relation of rheumatism and chorea is to be found in the morbid condition of the blood, which is admitted to exist in the rheumatic constitution; and this explanation will apply equally to chorea occurring in indi viduals or families inheriting the rheumatic diathesis ; to chorea oc curring in connection with rheumatism, but without the cardiac com plication; and to chorea associated with pericarditis or eudocarditis or both; the inflammatory affections of the fibrous tissues, as well as the spasmodic affections of the muscles, and the derangement of the nervous system, originating in the same specific disorder of the cir culating fluids." To this explanation of the choreic symptoms, there is the same objection that applied to a like mode of accounting for the nervous symptoms noted in pericarditis. If clue to the morbid condition of the blood, they ought to be much more common than they are; for that is a cause which operates in every case of rheuma tism. Occurring, as they do, only in exceptional cases, they are more
likely to result from an exceptional cause than from one which oper ates so generally.
The view that the chorea is consequent on a prior inflammation of the membranes of the heart is that which has commended itself to most other observers. There is some variety of opinion, how ever, as to the sequence of events by which the one phenomenon leads to the other.
Bright thought that the choreic symptoms resulted from irri tation transmitted from an inflamed pericardium or pleura along the phrenic nerve. This explanation might apply to cases of chorea occurring in connection with pericarditis or pleuritic; but is quite inapplicable to the numerous cases in which no such inflammation exists.
In more recent times the view has been advanced and ably advo cated by Kirkes, Hughlings Jackson, Broadbent, and others, that it is to endocarditis rather than to pericarditis that we have to look for the explanation of the choreic phenomena. The theory is, that some of the particles of lymph effused on the surface of the valves get de tached, enter the circulation, and cause embolic plugging of the minute vessels of the motor ganglia; and some pathological evidence has been adduced to show that the corpora striata and optic thalami have suffered in fatal cases of chorea. The actual existence of em bolism, however, has not been demonstrated; and its occurrence as a cause of chorea cannot be regarded as more than hypothetical.
That such an event is possible, there can be no doubt; but if particles of fibrin are detached from the valvular surface it is difficult to see why the vessels of other parts of the brain should not be plugged, as well as those of the motor ganglia; and why the embolic particles should not sometimes get into other organs and give rise to infarc tions of the lung, spleen, kidney, etc.