(From concutio, to shake together). \ concussion. A jolt or shock in consequence of blows or falls.

Concussion of the brain. An affection of the brain, produced by a violent shock, without a wound or fracture, though it must have been often the subject of observation, has been but lately distinguished with accuracy. It has been confounded with the effects of depression and extravasation; with inflammation and abscess of that organ. The two latter are often its consequences; but should be clearly distinguished in the origin. To take the simplest idea of the disease, we will suppose a cannon ball to pass near the head. The person falls insensible: if it passes near the spine, death, or a paralysis of the lower limbs, is often the consequence. From this there can be no organic injury; none can be traced by dissection: and though the momentum of the air may account for the fall, it will not explain the subsequent disease. This, however, will be a future consideration.

In concussion, the greater number of symptoms which distinguish compression are present. The great distinction is. that the pulse is soft, often weak, and sinks on bleeding. A discharge of blood from the nose or cars, and the apoplectic stertor,are wanting. After a short period has elapsed, the insensibility in concussion is not so great: the patient will complain on the head being moved. The muscles retain their natural tone, and the pupils are often contracted; they are, indeed, sometimes dilated; the insensibility is then extreme, and concussion and compression often so much resemble each other, that they cannot, perhaps, always be distinguished. What adds to the difficulty is, that after the insensibility from the simple concussion begins to wear off, inflammation often comes on; not active inflammation, with violent pain and delirium, but the milder kind, from a dilatation of the vessels, exciting, in consequence, a slight increased action. This, in many cases, unsuspectedly runs its course, till symptoms of compression come on; and, after death, an abscess is found generally at the base of the brain, though, occasionally, in other parts of that organ.

The best foundation of the distinction in these very difficult emergencies is the effects of remedies. In every accident of this kind, blood should be taken. If there is no wound, if there is no evidence of an actual blow, it should be taken sparingly. Should the pulse sink, the insensibility continue, we must content ourselves with injecting a clyster, and consider it to be a concussion. Should, however, any blow be discernible; should the patient, on pressing the cranium on every part, show more sensibility when pressed on one rather than any other part; should the pulse not sink on a moderate bleeding; we have reason to think the accident has produced a fracture or an extravasation.

Concussion is a disease similar to the effect of insolation, an affection of the nervous aura, equally produced by noxious vapours, by the simoon of the desert, particularly by lightning or electricity, which probably produce their effects only by the momentum communicated to the air. Why this concussion of the air should affect the nervous aura it is impossible to say, until its nature is better known. Shocks, however.

kind produce, in different parts of the body, similar effects. How often will a fall in old persons occasion infarctions or abscesses in the liver, independent of any topical bruise, or obvious inflammation! By such concussions the vessels are weakened, and admit of congestion: the load is greater than the debilitated powers can overcome, and suppuration is the consequence.

In cases of concussion, our conduct is by no means cleared from difficulties. When the pulse sinks from bleeding, and when we are satisfied, from the other symptoms, that no depression or extravasation has taken place, the warmest cordials have been ordered. Yet, as we have a second stage to dread, they should be employed with caution. Evacuations by clyster, topical discharges from the head, not, with the hasty rashness of some modern practitioners, at once, but in a gradual manner to keep up a constant effect, and prevent too great a stimulus in the early period, are necessary. We may, for instance, apply immediately leeches; but not more than four. At this time, a blister at the nape of the neck may be operating. After its discharge has begun, two may be applied behind the ears; and, after a similar interval, another to the vertex. During this period, the bowels should be kept moderately open; wine and nourishment supplied in sufficient quantities to support the strength, and preserve a vital warmth, without heating. The extremities should be kept warm by friction, and hot bricks, if cold.

Mr. Bromfield was led, seemingly by a happy accident, to give the Dover's powder; for which he afterwards substituted an antimonial with opium. When we consider the extent of the vessels over the whole surface of the body, and recal to our recollection the advantages we derive from an evacuation from the skin in every topical congestion, we shall at once sea the foundation of this practice, which, in his and other hands, has been found very successful. In reality, we consider it as one of the greatest improvements in modern practice; and, from the views we have given, the foundation of its use is particularly explained. Time. however, can only perfect the cure. The functions of the brain, if not hurried out of their regular train, exerted with too much energy, or too early, gradually recover, and the patient, at last, regains his former health: the time, however, is usually long.

If the patient has been neglected, or the plan not fully answered its intended purpose, though he appears to recover, yet, at an uncertain interval, shiverings, a low delirium, with marks of compression, come on. An abscess has then taken place, and death is inevitable.

Mr. Pott, in his description of concussion, has not distinguished sufficiently between the effects of the shock and extravasation; and Mr. Dease, though he approaches nearer to an accurate view of the subject, still confounds the two diseases.

(From Mr. Schmucker's view of the cause of the disorder, is suggested the idea of astringent applications; and he informs us, that he employed them with the greatest advantage. The following he seems to prefer: , Aq. pur. x. acet. acerrim. i. sal nitri: iv. sal. ammon. crud. ij. m. With this embrocation he orders the part affected to be frequently well bathed; at the same time that blood letting is prescribed, together with the internal use of nitre, stimulating injections, and laxatives. In all the slighter affections of the head, the greatest success, he says, has been observed from such a course; and, even in those which have required the trepan, Mr. Schmucker thinks he has often seen it employed with advantage. In concussions of the brain, even without any external wound, cold epithems and fomentations, he says, are very serviceable, especially if conjoined with stimulating clysters, and the application of leeches to the temples. Mr. Schmucker further observes, in the same work, that violent concussions of the brain are often produced merely from the passage of cannon balls near to the head, without any external affection being observable. In such cases, and in all similar concussions, emetics, he says, are commonly attended with the best effects; venesection, however, must always be premised.

See Berengarius de Commotione Cerebri; Mons. Bertrandi's Dissertation on the Concussion of the Brain, in the 3d vol. of the Memoirs of the Royal Academy of Surgery; Wiseman's Surgery, book v. ch. ix. obs. x. Gooch's Cases and Remarks, ed. 2. and Bromfield's Chirurgical Obs. and Cases, vol. i. ch. i. Dease's Obs. on Wounds of the Head; Pott's Works; Bell's Surgery, vol. iii. page 132. Abernethy's Surgical Essays.