GEN. II. Clonus. all clonic or agitatory motion of the muscles, while CONVULSIO is, nevertheless, retained in the Synopsis, as Clonic the technical name of that single species of disease which spasm. is colloquially called convulsion-fit, and not extended to any others. There is doubtless a difficulty in drawing the line between entastic and clonic spasm in many cases, from the mixed nature of the symptoms; but if it be felt of importance to take terms out of their general meaning, and tie them down to a stricter interpretation, such interpretation should be rigidly adhered to, or some degree of confusion must necessarily ensue. Natural but which do not im pede a continuity of To understand the real nature of the spasms we are Physiological explananow entering upon, it may be expedient to recollect that tion of the nervous power or fluid appears to flow naturally, as spasms. indeed we have already observed in the Physiological flow of the Proem to the present class, by minute jets, or in an un- nervous fluid, by dulatory course, like the vibrations of a musical chord. jets: But the movement is so uniform, and the supply so regular, in a state of health, and where there is no fatigue, that we are not conscious of any discontinuity of tenour, and can grasp as rigidly and as permanently with a muscle as if there were no relaxation in its flow of power. To prove the nature of the influx, however, nothing more is necessary than to reduce the muscle from a state of healthy tone to a state of languor, or to wear it down by fatigue; for in this condition all the muscles tremble, and the stoutest man is incapable of extending his arm with a small weight in his hand, or even of raising a glass of wine slowly to the mouth, without a manifest, and even a painful oscillation. muscular action. Natural mented by flow aug stimulants. The flow of the nervous power, in a state of health, is augmented by the application of various stimulants both mental and corporeal. The ordinary mental stimulus is various the will, but any other mental faculty when violently ex- Mental cited will answer the same purpose, though the action stimulants. which takes place in consequence hereof, will, in some degree, be irregular, as proceeding from an irregular source, and will in consequence make an approach to the character of spasms; of which a violent excitement of GEN. II. Clonus. Clonic spasm. Corporeal stimulants. of the flow of nervous fluid how interfered with. entastic spasm. almost any of the passions affords examples sufficiently evident, and especially the passions of fear and anger, under the influence of which it is sometimes found impossible to keep a single limb still. The ordinary corporeal stimulants are the fluids which are naturally applied to the motory organs themselves. Thus the air we breathe becomes a sufficient excitement to the action of the lungs, the flow of the blood from the veins a sufficient excitement to that of the heart, while the descent of the feces maintains the peristaltic motion of the intestinal canal. Where these stimulants are regularly administered, and the organs to which they are applied are in a state of health, the alternations of jets and pauses in the flow of the nervous power, as we have already remarked, are Uniformity uniform. But in a state of diseased action, whether from a morbid secretion of the fluid, or a morbid condition of the fibres that are to be influenced by it, this uniformity is destroyed, and in two very different ways: for first, the nervous energy may rush forward with a force that prohibits all pause or relaxation whatever, and this too in Production spite of all the power of the will; and we have then a of rigid or production of rigid or entastic spasms, or those abnormal contractions in different parts of the body of which the preceding genus furnishes us with abundant examples : and, next the pauses or relaxations may be too protracted; and in this case every movement will be performed with a manifest tremor. Where this last is the case, moreover, the succeeding jet, from the accumulation of nervous power that necessarily follows upon such a retardation, must at length take place with an inordinate force and hurry; and the movement in the voluntary muscles, when attempted to be controlled by the will, must be irregular and often strongly marked with agitation, giving us examples of convulsive or clonic spasm. clonic And as, moreover, in such a state of the nervous system any part of it, there will often be found a contest Mixture of between the retarding and the impelling powers; the spasm will not unfrequently partake of the nature of the Production of con vulsive or spasm. both kinds how pro duced. or of Clonus. two, the nervous energy, after having been irregularly GEN. II. restrained in its course, will rush forward too impetuously, and for a few moments without any pause; and we shall spasm. have either a succession of constrictive and clonic spasms in the same muscle or sets of muscles, or a constrictive spasm in some parts, while we have a clonic spasm in others and hence those violent and ramifying convulsions which we shall have more particularly to notice under the ensuing genus. A sudden and incidental application of any irritant Further power whatever, to any of the muscular fibres, will throw illustrated. them into an irregular action not only in a morbid state, when they are most prone to such irregularities, but even in a state of health. Hence the involuntary jerk that takes place in all the limbs when a boat, in which we are sailing at full speed, gets a-ground without our expecting it, or we are assailed unawares with a smart stroke of electricity. once pro tablished Now, whenever a forcible and anomalous movement of Tendency to à repetition this kind has once been excited in any chain of muscular of irregular fibres whatever, there is a strong tendency in them to action when repeat the same movement even from the first: and when duced: from accident or a continuance of the exciting cause it hence eshas actually been repeated, it forms a habit of recurrence habits of that is often broken off with great difficulty. Hence the recurrence exemplified convulsive spasm of the hooping-cough always outlasts in hoopingthe disease itself for some weeks, and is best removed by cough. the introduction of some counter-habit obtained by a change of residence, atmosphere, and even hours. A In palpipalpitation of the heart first occasioned by fright, in an tation: irritable frame, has in some cases continued for many days afterwards, and in a few instances become chronic. A habit of sneezing has sometimes been produced in In sneezing. the same manner, and has followed upon an obstinate catarrh; after which the slightest stimulants, even the sneezing of another person, has been sufficient to call up fresh paroxysms, and in some cases which I have seen, of very long and troublesome continuance. Hiccough affords us another example of the same ten- In hiccough. Clonus. Clonic spasm. GEN. II. dency to a recurrence of muscular abnormities. This is usually produced by some irritation in the stomach, not unfrequently that of fulness alone: the irritation is by sympathy communicated to the diaphragm, which is thrown into a clonic spasm, and the spasm being a few times repeated, the series of hiccuping becomes so established, as, in many instances, to be broken through with considerable difficulty. It is to these physiological laws that most of the affections we are now about to enter upon are referable; and the concentrated view we have thus taken of their operation, will render it less necessary for us to dwell at much length upon any of them. The genus CLONUS comprises the six following species: GEN. II. Disease principally seated in the SPECIES I. CLONUS SINGULTUS. Hiccough. CONVULSIVE CATCH OF THE RESPIRATORY MUSCLES, WITH THOUGH the spasmodic action in this affection exists chiefly in the diaphragm, the principal seat of the disease is the stomach, when strictly idiopathic; an obser GEN. II, SPEC. I. Clonus vation which was long ago made by Hippocrates, and has in recent times been more copiously dwelt upon by Hoffman: but which Mr. Charles Bell has been the first to Singultus. establish by experiments on the nervous system. miting", says he, " and hiccough, are actions of the respi- when idioratory muscles excited by irritation of the stomach."* " Vo Debility is perhaps the ordinary remote cause, and irritability, or some accidental stimulus, the exciting. Thus excess of food, and especially in a weak stomach, is often a sufficient stimulus: and hence the frequency of this complaint among infants. Hiccough. stomach pathic. Remote and exciting causes. cause some For the same reason it is occasionally produced by worms, acidity, or bile in the stomach. External pressure on the stomach is another exciting cause: and hence it has sometimes followed, on an incurvation of one or more of the ribst, or of the ensiform cartilage of the sternum produced by violence, and pressing on the coats of this organ. The stomach, however, is not at all times the Morbid only organ in which the morbid cause is seated that ex- times cites the diaphragm to this spasmodic action. The liver seated in is frequently to be suspected. "I have often", says Dr. other organs Percival, in his manuscript notes on the volume of Nosology, "found hiccough symptomatic of an enlargement or inflammation of the liver on the upper convex side." It also frequently follows upon strangulated hernia; and, Exemplified. according to Mr. John Hunter, in numerous instances accompanies local irritation after operations of various kinds. It has sometimes attended the passage of a stone in one of the ureters, and has continued through its entire course §. The affection is often very troublesome, but it cures itself in ordinary cases, and where the exciting cause is lodged in the stomach; for the spasmodic action very generally removes the accidental irritant; and if not, the • Experiments on the Structure and Functions of the Nerves. Phil. Trans. 1821, p. 406. Schenck, Lib. 111. Obs. 49. ex Fernelio. Bonet. Sepulchr. Lib. 1. Sect. v. Obs. 8. Appex. than the stomach. Spasm often cures itself or is easily re strained. |