THE NERVOUS SYMPTOMS OF CARDITIS.
To the occurrence of head symptoms in connection with inflam mation of the heart and its membranes, attention has already been directed; and two cases have been given in which all the symptoins during life pointed to inflammatory mischief within the cranium, but in which after death there was found nothing abnormal within the head, but only the indications of inflammation of the heart and its investing membrane.
Since these cases were recorded, much attention has been given to this subject, and the observations of Bouillaud, Macleod, Hawkins, Bright, Burrows, Latham, Fuller, and others, have demon strated that inflammation of the heart and pericardium is a frequent cause of head symptoms in acute rheumatism. It is chiefly in con nection with pericarditis that they have been noted; this is no doubt because it is more frequent and more readily diagnosed than myocar ditis. As already remarked, it is probable that the head symptoms attributed to the pericarditis are in many cases indicative of a co incident myocarditis.
In studying the pathology and mode of production of the symp toms three possible causes have to be considered : 1. The morbid condition of the blood; 2. The cardiac inflammation; 3. The nervous constitution of the sufferer.
1. A morbid condition of the blood was the explanation on which our fathers, with the views which they held regarding the pathogen esis of acute rheumatism, naturally fell back. "A distempered con dition of the blood I conceive to be the true proximate cause of the sensorial disturbance occasionally observed in the course of acute rheumatism" (Fuller).
"Those remarkable cerebral affections—the wild delirium and violent mania—which not 'infrequently occur in the course of rheu matic fever, or follow in its train, and which have usually manifested themselves along with the cardiac complications, causing doubt and perplexity in the mind of the physician as to the real organ affected, and the true nature of the disease, are to be explained by the morbid condition of the blood which is admitted to exist in the rheumatic constitution" (Begbie).
But this morbid condition of the blood exists in every case of rheumatic fever. If it sufficed for the production of nervous symp toms, such symptoms would be the rule and not the exception, and delirium would be as common in rheumatic fever as it is in typhus. Such an explanation, too, rather leaves out of account the heart trouble in connection with which these symptoms are noted.
2. The Cardiac Infianonation.—Recognizing the insufficiency of this hypothesis, Sir Thomas Watson thought these symptoms might be due to disturbance of the cerebral circulation, resulting from em barrassment of the heart's action. The objection to this view is that the cases in which nervous symptoms are most marked are not, as a rule, those in which evidence of cardiac embarrassment occurs, but, on the contrary, those in which there are no subjective symptoms of heart disturbance, and nothing to direct special attention to that organ. The heart's action may be more embarrassed when the inflammation affects the membranes, than when it is confined to the muscular substance.
But inflammation of the muscular substance causes more marked nervous symptoms. Cardiac embarrassment causes its own special symptoms, but disturbance of the nervous centres is not one of these. Such symptoms are more noted in cases of myocarditis in which there are no cardiac symptoms to attract attention—Corvisart's latent cases.
3. The Nervous Constitution of the Patient.—It is not unlikely that individual susceptibility may in some cases have something to do with their production. In all acute febrile ailments nervous symp toms are apt to occur. They are especially apt to do so in persons of susceptible and delicate nervous organizations. In his remarks on his case of pericarditis with delirium already quoted Andral says : " Qu'en raison des susceptibilites individuelles, it n' est point d' organe dont la lesion ue puisse determiner les symptomes nerveux les plus varies, de maniere a produire sympathiquement les diff4rens etats morbides dont on place le siege dans les centres nerveux et leurs This individual susceptibility is a factor to be borne in mind in explaining the occurrence of delirium in a given case of pericarditis. But probably a more important factor is the extent to which the muscular substance of the heart is inflamed; for the occurrence of delirium in a case of pericarditis may be regarded as evidence of accompanying myocarditis. This disturbance of nerve centres may he partly due to malnutrition consequent on inefficient cardiac action, but mainly to the disturbance which must result from acute inflam mation affecting an organ of such importance as the heart. We have already seen that delirium in some form is the leading symptom in my ocarditis.