§ 2. Chorea and Tetanus.—This is perhaps the best place to notice two diseases which stand on the confines of general disorder of the whole system, and special derangement of the nervous element in it. They are marked by striking objective phenomena, which consist of acts of the muscular system not only involuntary, but incontrollable. These acts may be associated with a variety of other symptoms, as they may be with differing conditions of internal organs; but the muscular movement stands by itself as the sole indication by which the disease is recognized. Here diagnosis has but little to do. The element of the disease is quite unknown to us, and hence it is to the prominent symptom alone that we have as yet to look for the discrimination of each ; to this symptom the name of the disease is applied, and by this is it characterized.
The movements of chorea once seen can never be forgotten or mistaken ; nor can the fearful spasms of tetanus be taken for anything else. It is true that in severe lesions of the brain, when the patient is in a state of stupor, or of delirium, convulsive movements may be seen in some cases, spasms of muscles in others; but n9 one who has seen the diseases can ever mistake them for chorea or tetanus.
It is quite fqreign to the purpose of this work to draw pictures of disease, as our sole consideration is the ground upon which diagnosis is to be formed. In chorea we rely upon the restless jactitation, the tossing hither and thither in the most uncertain manner of one or more limbs, or of the whole body. In tetanus, on the sudden and violent contraction of various sets of muscles, frequently alternating with as sudden relaxation. In chorea the system at large does not suffer much disturbance, except when other conditions of dis ease are associated with it: in its more severe forms the expression of the features is almost maniacal, and the patient becomes gradually exhausted from constant restlessness, inability to take food, and insomnia, terminating in delirium, coma, and death. In tetanus the system early indicates febrile disturbance of a low and adynamic chafacter, and the disease is generally attended by rapid sinking and prostration. The spasm of tetanus is sudden in its invasion, alternating with relaxation ; it can scarcely be confounded with permanent spasm or contraction of particular muscles, which is con stantly associated with organic diseases of the nervous centres, especially with certain forms of pressure, and with induration of the brain or cord.
Both chorea and tetanus may be simulated by hysteria ; but the imitation is not such as can impose upon any one who has observed the true disease and is prepared for such a simulation. In hysterical movements there is necessarily more method than in those of chorea ; in hysterical spasm there is seldom the exact correspondence in the condition of a whole set of muscles found in true tetanus. In either case, when the suspicion is awakened, the abstraction of the patient's attention will serve to interrupt the movements or relax the spasm.
These diseases are generally found associated with some cause of irritation ; it may be said, perhaps, that they are always so, although our means of analysis frequently fail in detecting it. In chorea we have to seek for some shock to the nervous system in sudden fright, or some irritation in the digestive system •, loaded bowels, worms, &c. : sometimes the vascular system is deranged, and there may be a condition of metala or disease of the heart; not unfrequently it is associated with that peculiar condition of blood that manifests itself in rheumatism ; sometimes there is disease in the nervous system, but it has been less uniformly traced to this than to the other conditions already enu merated.
In tetanus we inquire whether it be dependent on the irritation of some particular nerve, or on some obscure affection of the brain or spinal cord ; whether it be eccentric or centric ; traumatic, from the irritation of a wound, or idiopathic, without known cause ; in the latter case the question whether it have arisen from the administration of poison is suggested by the fearful revelations of recent times. Our investigations can reach no further.
§ 3. Delirium Tremens.—We must also class this as a disease which involves something more than mere disorder of the nervous centres. It seems to be due to perverted nutrition of the brain consequent on the circulation through its mass of impure blood unsuited to develop healthy functions. Its relation to the nervous system is somewhat similar to that of mania : in classification neither of them can be regarded as diseases of the nervous system, because in each there is an element extraneous to it; but in their development they are so intimately associated with it that we cannot doubt that they are accompanied by hidden change of structure. With reference to diagnosis, it will be more convenient to consider this disease, when speaking of delirium as a symptom of the condition of the brain, where its relations to other forms of delirium will be more easily exhibited. But there are certain general objective phenomena by which it is marked ; it is a de lirium cum tremore. Tremor is its essential characteristic, which every act of the patient betrays : the hand cannot be held still ; but there is neither the jactitation of chorea, nor the regular shake of paralysis agitans ; the tongue quivers when protruded ; and these movements differ from the ordinary tremulousness of pure nervous debility, in the rapidity and excitement with which each act is performed. The patient sits down and gets up in a hurry, he raises himself in bed with a spring, he turns suddenly round to the person who addresses him, he thrusts forward his hand for the pulse to be felt, and he puts out his tongue with the same quick unsteady movement, when directed to do so.
All this may occur before any delirium has showed itself. From the patient himself; or his friends, it will be learned that he has either lately had a drinking bout, or that, being an habitual drunkard, he has been, under circumstances of privation, debarred from his accustomed stimulus; perhaps, that there has been some mental anxiety, and, along with this, his last few nights have been sleepless. He will say that he has been long ailing, that his pre sent state has been supervening for weeks or months, and will often be exceedingly shy of telling that there has been any re cent aggravation of his symptoms, or that they have, as we may be well assured from other sources, all come on within a few days : this appears to arise from a consciousness of the real cause of his malady, which he vainly fancies he may conceal ; but it is worthy of noting, because it might lead to a mistaken diagnosis.
The pulse is soft, often large, sometimes weak and quick. The tongue is evenly coated with a moist creamy fur. The skin is warm, frequently perspiring; but in the early stage it may be dry, and often exhaling somewhat of a rheumatic odor; it has never the heat and pungency of fever. In former days, when delirium was regarded as evidence of inflammation, depletion was no less had recourse to in this than in the delirium of typhus fever or of mania : but in this practice essential symptoms were evidently overlooked—that of the pulse and the moist tongue ; and just as in attempting to form a correct diagnosis, so for the purpose of adopting sound treatment, the totality of symptoms must be considered in place of the mind being fixed on one which is remarkably prominent.