In other cases heiniplegia, more or less ge neral and perfect, followed the operations after a longer or shorter period. In a case related by Magendie, that of a young girl, in whom the left carotid was tied, there appeared on the sixth day paralysis of the right arm, of the pharynx and larynx, and numbness of the right lower extremity. The -paralysis gradually di minished, but the intellect was so far impaired that the patient lost the power of reading.* In Sir A. Cooper's first case, the right arm and leg were deprived of sensation and in part of motion on the seventh day after the operation; and a man, in whom Mr. Vincent tied the right carotid for aneurism, was attacked with com plete hemiplegia of the left side in half an hour after the operation, and continued in that state till his death on the seventh day. It is re markable that, in all these cases, the paralysis was situated on the side opposite to that on which the artery was tied ; a fact which alone would indicate that the cause of the paralysis was seated in the brain.
Aneurisms do not occur so frequently in the carotid arteries as in the aorta or in the large arteries of the extremities. They are most frequently found situated at the bifurcation of the common cafotid, where also calcareous and atheromatous deposits are very often met with. In the lower part of the common ca rotid an aneurism is, of course, a more for midable disease than if it were situated high up, in consequence of the impossibility of applying a ligature between the artery and the heart. Sometimes an aneurism of the aorta projects upwards into the neck, compressing and obliterating the carotid, and simulating all the characters of aneurism of its lower portion. I am not aware that there is on record any instance of aneurism of the internal carotid artery in its cervical portion, although our mu seums are not without specimens of aneurismal dilatations of it after it has entered the cranium, and as it lies by the side of the sella Turcica.
We sometimes find the cervical portion of this artery in a tortuous state, but we rarely see in it those atheromatous and earthy deposits which are met with in other parts of it.
In the dead body there is no difficulty in exposing the common carotid artery in any part of its course, but during life much em barrassment is occasioned by the alternate di latation and collapse of the internal jugular vein, corresponding with expiration and inspi ration, and sometimes by some small veins which lie in front of the artery. It may be cut down upon either above or below the omo hyoid muscle, but in the former situation the superficial position of the vessel and the less complexity of its relations render it more easy to be got at. In both situations the anterior margin of the sternomastoid muscle forms a useful guide to the artery ; but much more careful dissection is required when the operation is done in the region below the omohyoid muscle. Here great care is de manded in dissecting back the sternomastoid muscle, and in drawing the sternothyroid inwards ; the thyroid body and, on the left, the cesophagus must be avoided, and in pas sing the ligature round the artery, the ope rator must take care to avoid not only the vein and par vagum but also the inferior thyroid artery, the recurrent and sympathetic nerves and the cardiac branches of the latter, and on the left side the thoracic duct. As anomalies
in the distribution of some of the arteries in the neck are occasionally met with, the surgeon should be on his guard against such an occur rence, especially in operating in the low region where they are most likely to be met with. Two arteries may be found here occupying pretty nearly the situation of the carotid artery. One of these will be the carotid itself, the other the vertebral, which sometimes passes high up in the neck in front of the rectus capitus anticus muscle, before it enters the canal in the transverse pro cesses of the cervical vertebrx. In a case related by Mr. Allan Bums,'' the vertebral artery en tered this canal only a few lines below the bifur cation of the carotid, and in its passage up the neck, parallel to and behind the carotid, it was separated from that vessel only by its sheath. A low bifurcation of the carotid artery would be equally likely to occasion embarrassment ; and the possibility of such a condition of the cer vical vessels as well as of the anomalous course of the vertebral artery before alluded to are strong arguments in favour of the recommenda tion of Mr. Burns, that, " when the surgeon has.reached the sheath of the vessels he ought uniformly, before opening it, to press the carotid between the finger and thumb. If the pulsa tion of the tumour be not in this way con trolled, he will do well to pause before he pass a ligature round that vessel."-t- In fine we sometimes find the inferior thyroid artery cros sing in front of the common carotid in the inferior region.
It is very easy in the dead body to find the primitive carotid low down in the neck by cutting in the cellular interval between the clavicular and sternal portions of the sterno mastoid muscle, but it is not so easy to pass a ligature round it; and this difficulty is greatly magnified in the living subject, in consequence of the necessarily limited space in which the operator has to work ; the difficulty too is greatly increased by the contractions of the sternomastoid muscle.
To expose the external carotid artery shortly after its origin, it is only requisite to follow the same steps as are necessary for cutting down on the common carotid above the oinohyoid muscle. It is in general advisable to apply the ligature below the point at which the di gastric muscle crosses the artery and below the origin of the superior thyroid. Some embar rassment is likely to result from the plexus of veins which in this region often lies in front and on the sides of the artery. A ligature, however, may be passed round this artery above the digastric muscle, but it will be re quisite that the external incision shall com mence higher up. The needle must be passed between the parotid gland and the digastric tendon, the distances between these parts hav ing been previously increased by drawing down the tendon of the muscle.