Page:Encyclopædia Britannica, Ninth Edition, v. 21.djvu/222

Rh 202 S T VITUS'S DANCE nervous system occurring for the most part in children, and characterized mainly by involuntary jerking move- ments of the muscles throughout almost the entire body. It is to be regarded as a functional nervous disorder of wide extent, the manifestations of which appear not merely in disturbance affi'-ciing the motor apparatus but in various associated morbid phenomena of cerebral origin. Among the predisposing causes age is important, chorea being essentially an ailment of childhood and more par- ticularly of the period in which the second dentition is taking place. The greater number of the cases occur between the ages of nine and twelve. It is not often seen in very young children nor after puberty ; but there are many exceptions to this rule. It is twice as frequent with girls as with boys. Hereditary predisposition to nervous troubles is apt to find expression in this malady in youth, more especially if the general health becomes lowered. Of exciting causes strong emotions, such as fright, ill-usage or hardship of any kind, insufficient feeding, overwork or anxiety, are among the most common ; while, again, some distant source of irritation, such as teething or intestinal worms, appears capable of giving rise to an attack. It is an occasional but rare complication of pregnancy. The connexion of chorea with rheumatism is now universally recognized, and is shown not merely by its frequent occur- rence before, after, or during the course of attacks of rheumatic fever in young persons, but even independently of this by the liability of the heart to suffer in a similar way in the two diseases. The symptoms of St Vitus's dance are in some instances developed suddenly as the result of fright, but much more frequently they come on insidiously. They are usually preceded by changes in the temper and disposition, the child becoming sad, irritable, and emotional, while at the same time the general health is somewhat impaired. The first thing indicative of the disease is a certain awkward- ness or fidgetiness of manner together with restlessness, the child being evidently unable to continue quiet, but frequently moving the limbs into different positions. In walking, too, slight dragging of one limb may be noticed. The convulsive muscular movements usually first show themselves in one part, such as an arm or a leg, and in some instances they may remain localized to that limited extent, while in all cases there is a tendency for the dis- orderly symptoms to be more marked on one side than on the other. When fully developed the phenomena of the disease are very characteristic. The child when standing or sitting is never still, but is constantly changing the position of the body or limbs in consequence of the sudden and incoordinate action of muscles or groups of them. The shoulder is jerked up, the head and trunk twisted about, the limbs crossed suddenly and changed again, the fingers keep moving restlessly, while the face is distorted with grimaces, frowning and smiling irregularly. These symptoms are aggravated when purposive movements are attempted or when the child is watched. Speech is affected both from the incoordinate movements of the tongue and from phonation sometimes taking place during an act of inspiration. The taking of food becomes a matter of difficulty, since much of it is lost in the attempts to convey it to the mouth, while swallowing is also inter- fered with owing to the irregular action of the pharyngeal muscles. When the tongue is protruded it comes out in a jerky manner and is immediately withdrawn, the jaws at the same time closing suddenly and sometimes with con- this dancing mania were wont to resort to the chapels of St Vitus (more than one in Swabia), the saint being believed to possess the power of curing them. The transference of the name to the disease now under consideration was a manifest error, but so closely has the association now become that the original application of the term has been com- paratively obscured. siderable force. In locomotion the muscles of the limbs act incoordinately and there is a marked alteration of the gait, which is now halting and now leaping, and the child may be tripped by one limb being suddenly jerked in front of the other. In short, Avhether at rest or in motion the whole muscular system is seen to be deranged in its operations, and the term " insanity of the muscles " not inaptly expresses the condition, for they no longer act in harmony or with purpose, but seem, as Trousseau ex- presses it, each to have a will of its own and to be exercis- ing this for different objects at one time. The muscles of organic life (involuntary muscles) appear scarcely, if at all, affected in this disease, as, for example, the heart, the rhythmic movements of which are not as a rule impaired. But the heart may suffer in other ways, especially from inflammatory conditions similar to those which attend upon rheumatism and which frequently lay the foundation of permanent heart : disease. In severe cases of St Vitus's dance the child comes to present a distressing appearance from the constant restlessness and disorderly movement, and the physical health declines. Usually, however, there is a remission of the symptoms during sleep. The mental condition of the patient is more or less affected, as shown in emotional tendencies, irritability, and a somewhat fatuous expression and bearing, but this change is in general of transient character and ceases with convalescence. This disease occasionally assumes a very acute and aggravated form, in which the disorderly movements are so violent as to render the patient liable to be injured and to necessitate forcible control of the limbs or the employ- ment of anaesthetics to produce unconsciousness. Such cases are of very grave character, if, as is common, they are accompanied with sleeplessness, and they may prove rapidly fatal by exhaustion. In the great majority of cases of St Vitus's dance, however, complete recovery is to be anticipated sooner or later, the symptoms usually con- tinuing for from one to two months, or even sometimes much longer. The nature of this disease has given rise to much dis- cussion and there still remains considerable difference of opinion as to its true pathology. The fact that the vast majority of cases recover would seem to show that there could have been no profound change in the structural integrity of the nerve-centres, while in those instances where a fatal result takes place post-mortem examination reveals no constant morbid condition. A theory supported by high authority has referred the cause of the malady to the plugging up of minute blood-vessels in the motor centres of the brain (a condition not unlikely to occur in rheumatic inflammation affecting the lining membrane of the heart), and such a change has been seen in a few instances. In a still larger number, however, no appear- ances of this kind have been observed, but simply vascular changes of a congestive character widely diffused through- out the central nervous system, accompanied with evidences of slight inflammatory action. Dr Dickinson, whose views, founded upon carefully conducted investigations, are those most widely accepted, concludes as follows : " We see in chorea a widely distributed hypersemia [i.e., congestion] of the nervous centres, not due to any mechanical mischance, but produced mainly by causes of two kinds, one a morbid, probably a humoral influence, which may affect the nervous centres as it affects other organs and tissues ; the other, irritation in some mode usually mental but some- times what is called reflex, which especially belongs to and disturbs the nervous system, and affects persons differently, according to the inherent mobility of their nature." For the treatment of St Vitus's dance the remedies pro- posed have been innumerable, but it is doubtful whether any of them have much control over the disease, which