porarily restraining hemorrhage during serious incisions of the head or neck, could not be borne with impunity. Cerebral affection rapidly formed, the compressing hand of the assistant had to be removed, and relief came with the renewed flow of blood. But there seems every reason to believe, that in this the carotids were not at all concerned. In two ways the functions of the encephalon may be seriously disturbed;-either by a deficiency of its arterial supply, or by an over-accumulation of its blood, more especially of its venous portion. The latter seems to have been the morbific agent in the circumstances just detailed, the head symptoms being produced not by obstruction of the carotids, but by arrestment of the venous return in the internal jugulars. Such occurrences, therefore, are not to be looked upon as indicating danger to the brain by interference with the carotids alone.

To the question, apparently still an open one-" May both carotids be tied at once, without immediate danger to the brain, and with the prospect of a favourable result?". -an answer in the affirmative seems to be contained in the last number of the Memoirs of the French Academy;2 with an additional piece of information of much practical importance,-that, after such an operation, the lung, and not the brain, is the organ to be suspected and watched. M. Robert, (de Lamballe) after narrating a case in which ligature of the common carotid was successfully performed, on account of aneurism by anastomosis of the orbit, details the results of numerous experiments on animals, instituted with the view of ascertaining what are the actual dangers of simultaneous ligature of these vessels. Previous experimentalists have arrived at very conflicting conclusions on the same subject, into which we need not enter, except to suggest, in passing, how probable it is that many of the untoward results have depended on the inexpertness of the operators, and not on mere ligature of the arteries. M. Robert's resumé of his experiments is as follows:-The vertebral arteries are sufficient for the cerebral circulation. Ligature of both carotids produces no disturbance, either primary or consecutive, of the nervous system or the senses; for in no animal has he observed any lesions of

1 Late experiments, by Dr John Reid, seem to have determined that, in asphyxia, cessation of the sensorial functions does not arise from diminution of the arterial supply of the brain, but from the circulating blood being of a venous character, and so failing to afford to that organ the excitation requisite for the performance of its functions.-Edin. Med. and Surg. Journ. No. 147, p. 450, and Abstract of Dr R.'s Memoir, at p. 668, No. IX. of this Journal, for 1841.

The safety of simultaneous ligature of two of the principal cervical arteries, in the lower animals, is also demonstrated by experiments conducted by Mr James Spence, and published by Dr Monro, in the "Essays of Dr Monro secundus," p. 95, foot-note. The beautiful preparations resulting from the operations, illustrative of collateral circulation, are preserved in the anatomical museum of the University.

sight, hearing, intellect, or motion. His experiences, in regard to both men and animals, do not warrant the belief that ligature of one or both carotids can produce palsy and alteration in the brain. The cerebral circulation continues after ligature of both carotids, as is shewn by an opening made in the vessels above the ligature. No dysphagia occurs. In the dog, rabbit, calf, and sheep, only a momentary oppression of the respiration is observed; while in horses, death almost invariably occurs; not by alteration in the nervous system, but by a severe lesion of the lung. The symptoms of disturbance in the respiratory organs are diminished by bleeding before and after the operation. The pulmonary lesion is shewn to be diminished in consequence of the bleedings. Hence he infers the propriety of bleeding "strong men" both before and after the operation, in order to avoid congestion. of the lungs. For in his experiments "on several kinds of animals, ligature of the carotids caused no lesion of the cerebral functions; all the untoward symptoms were connected with the respiratory organs, and dissection shewed the lung transformed into a ceritable poche de sang. Death came from the last organ, and not from the brain, which preserved its integrity."

All the horses died within a few hours, the more rapidly, the more vigorous the animal. It is only since the publication of his memoir, that he has ascertained the possibility of saving the horse after such an operation. The remote cause of death in this animal he supposes to exist in a peculiarity of the vertebrals, which diminish remarkably in size as they enter the cranium, being there no larger than those of the dog. He considers that in consequence of their diminished size, they are unable to maintain an efficient balance in the circulation after ligature of both carotids; they cannot duly carry on the increased amount of blood which is thus thrown on them; and the result is a congestion of the lungs, which, unless relieved by bleeding, ends in fatal apoplexy of that organ. But the brain is undisturbed, for the vertebrals, small as they are in this instance, are yet found sufficient for its arterial circulation; and the venous return ought to be little if at all interfered with by the operation. In the other animals, the vertebrals are of a uniform calibre; and, in consequence, they are much less liable to suffer from the pulmonary lesion.

any

In no animal did affection of the brain and nervous system, primary or consecutive, follow his operations, unless in those cases in which he had wilfully either tied or cut across one or all of the nerves which accompany the carotids.

Bringing the results of these experiments to bear upon the human subject, we infer:-1. In future the surgeon need not hesitate to secure both common carotids by ligature simultaneously, should circumstances imperatively demand such a severe

proceeding. For it is highly improbable that the brain shall suffer by diminution of its arterial supply, seeing that in the horse the vertebrals, even though remarkably contracted in size, are found sufficient for this; and it being probable that the comparatively greater size of the human brain, with its consequent greater capacity for arterial blood, will be fully compensated by the comparatively larger size and full anastomotic circulation of the vertebral arteries.

2. The operation must be performed with much delicacy and skill, and with an especial regard to the safety and integrity of the accompanying nerves and vein. For, in the experiments of M. Robert, it was only when the former were cut or tied, that nervous symptoms," such as difficulty of swallowing, change of voice, derangements of the senses, abnormal movements, and other obvious disturbances of the cerebro-spinal functions, were ever found to supervene. And, as already stated, there seems every reason to believe that arrestment or interference with the return in the jugulars is fraught with infinitely greater danger to the encephalon, by inducing venous congestion there, than is the sudden limitation of its arterial influx to the vertebral supply. In tying other arteries, experience has made us well aware how dangerous it is in any way to injure the venous coats by the needle or ligature; inflammation of these coats, with obstruction of the canal at the point of injury, (the mildest form of phlebitis,) is one of the gravest accidents that follow the operation; and it is very plain that such an accident to the internal jugular must be peculiarly disastrous.

3. After ligature of the common carotid, and more especially after deligation of both arteries, supposing the operation or operations to have been performed with due regard to the foregoing precautions, the attention of the surgeon ought to be wakefully directed to the organs of respiration; in as much as the experiments of M. Robert declare theirs to be the texture in danger, not the cerebral. And if, on investigation, it be found that in the autopsies of unfavourable cases of obstruction of the common carotid in the human subject, recent lesions, more or less important, of the lungs have been disclosed, the precautionary injunction will become all the more imperative.

It may, perhaps, be reasoned thus, that pulmonary lesion is found to result from injury, by wound or ligature, of the par vagum; that the carotic ligature may be supposed, in the first instance, to affect the brain, and, through the influence of the eighth nerve, involve the lungs in disease secondarily; and that thus, after all, the brain is the organ in danger. But how is this nerve alone singled out for morbid action, the rest of the nervous system remaining undisturbed? It is plainly stated by M. Robert that, in none of his experiments, where the arterial tissue

was alone interfered with, did there occur any indication, however slight, of cerebral disturbance. We are still forced, therefore, to the belief that the brain is not affected by mere diminution of its arterial supply; and that the change of structure in the lungs, resulting from such an operation, is not effected through a perverted influence from the eighth pair of nerves.

4. The form of danger to be apprehended is congestion of the lungs; in other words, an unwonted determination of blood to that organ, caused by a sudden and serious disturbance of the due and healthful balance in the arterial circulation, and resulting either in apoplexy of the lung, if the congestion have occurred rapidly and to a great extent; or in an inflammatory action more or less destructive to the pulmonary texture.

5. To obviate this danger, it will be prudent, more especially in plethoric subjects, to draw blood-the amount varying according to the circumstances of the case-shortly before the performance of the operation, in order to prevent, or at all events diminish this probable interruption of the arterial balance. And in the after treatment of the case, further bleeding will probably be necessary, either to avert evil consequences from the determination to the lungs, which may have taken place notwithstanding all precaution, or to limit or abate the morbid action which may have not only threatened but actually occurred. It will not be sufficient to moderate the heart's action, and the arterial circulation, by antimonials, sedatives, &c.; it is essential that the actual amount of the circulating fluid be diminished.

6. This prophylactic principle need not be confined to deligations of the carotid alone. In operations on other vessels of the first class-subclavians, iliacs, femorals-important internal organs may be saved, and the number of successful issues materially increased, by a precautionary bleeding to a moderate extent, before the operation, and by a more watchful and better directed surveillance than heretofore, during the after treatment. 7. Without coming under the bann of uncharitableness, we may be allowed to suspect that in most, if not all of those cases in which important cerebral affection has supervened, the mere obstruction of the arterial current was not to blame; but that the nerves or vein accompanying the vessel had been more or less injured by the knife, the ligature, or otherwise, during the dissection; or, after the operation, casualties may have occurred in or around the wound, sufficient to account for "nervous affections" of consecutive formation; or cerebral disease has either been induced or aggravated by accidents wholly irrelevant of either the operation or the disease on account of which it was undertaken.

I have been led to place the foregoing observations before your readers, conceiving them to be of practical importance to

the operating surgeon, and fairly deducible from the experiments of M. Robert, and more especially as they seem, to a certain extent, to be borne out by the case of ligature of the common carotid, on the distal side of the tumour, published by Mr Fergusson, in the November Number of the Journal. His patient did not suffer from ulceration of the deligated artery, followed by bleeding,-the ordinary cause of death in unsuccessful cases, but died within the period of the ligature's separation. On the evening of the same day on which the operation was performed, he complained of slight dizziness and "difficulty of breathing, but was otherwise comfortable." May not that have been the result of pulmonary congestion having commenced to form? On the day after, there was "slight pain in the neck during deglutition;" but that was probably the result of inflammation in and around the wound, which is stated to have occurred to a considerable extent. On the 5th day, he is represented as "much troubled with cough, attended with difficult respiration," and "annoyed by mucus collecting in the larynx. The bronchial tubes seemed partially filled with an excess of mucus, and he occasionally, though with seeming reluctance, complained of slight pain in the chest while coughing." Now, the congestion was doing its evil work; an important morbid action had resulted, and was progressing. On the sixth day, we find him "much troubled by cough and difficult expectoration; his breathing somewhat hurried, his countenance anxious, and in his manner an appearance of distress, for which it was difficult to ascribe a direct cause." These pectoral symptoms increased; blood was now drawn for the first time, and was found to possess the inflammatory characters. The cough and expectoration were somewhat relieved, but the oppression of respiration continued to augment, and he sank on the evening of the seventh day. On dissection, the left lung was found to exhibit the mark of no recent lesion, excepting in the middle lobe, which is said to have been "of a darker colour, and more consolidated than any other part of the organ. In all parts of the upper and lower portions of the right lung, (the same side as the deligated artery,) there seemed a greater quantity of mucus than was natural, and the parenchyma of the middle lobe was gorged with blood and mucus; here and there patches of recent lymph were observable, and several of these were mingled with small effusions of pus." Were not these things the results of an inflammatory action caused by the congestion? and was not this congestion consequently the remote cause of death?-for a careful examination is said to have disclosed no other organic lesion, which could have been connected therewith. At the conclusion of the paper, Mr Fergusson states that he has "often wondered since, what might have been the effect of the abstraction of blood at an earlier period of the treat