PRACTICAL CONSIDERATIONS: VERTEBRAL ARTERY. 761 



Practical Considerations. — The vertebral artery may require ligation on 

 account of wounds, or of traumatic aneurism of the vessel itself, or (in addition to the 

 ligation of other vessels) in aortic or innominate aneurism, or to prevent or arrest 

 secondary hemorrhage after ligation of the innominate. 



Aneurism — except from wound — is excessively rare, the vessel being well sup- 

 ported, first between the scalenus anticus and the longus colli muscles and then in the 

 bony canal in the transverse processes. Only one case of spontaneous aneurism of 

 the cervical portion of the artery has been reported (Hufschmidt). 



Traumatic aneurism is more frequent, but, on account of the vessel's depth, is rare. 



Paralysis of some of the tongue muscles has been attributed to pressure on the 

 hypoglossal nerve by a vertebral aneurism and severe occipital headache to pressure 

 on the suboccipital nerve. 



Digital compression of the vertebral is possible below Chassaignac's carotid 

 tubercle {g.v.), — i.e., below the level of the cricoid cartilage, if pressure is made in 

 the line of the great vessels. Alternating pressure above and below this level is of 

 great diagnostic value in distinguishing the source of the bleeding, or of the supply of 

 blood to a pulsating tumor, after a deep wound of the neck. Pressure along the line 

 of the common carotid below the tubercle — i.e., for from two to two ana a half inches 

 above the clavicle — will usually arrest such bleeding and puistaion, no matter whether 

 the vertebral or either of the carotids is involved. Pressure above the tubercle will 

 affect only the carotids and their branches, but — except in the presence of an anomaly 

 — will leave unchanged a flow of blood or an aneurismal pulsation proceeding from 

 the vertebral. Furthermore, as in one of the not infrequent vertebral variations 

 {vide supra), the artery may not enter its vertebrarterial foramen until it reaches the 

 fifth, fourth, third, or even the second transverse process, and as, in such a case, it 

 would be effectually compressed when pressure was applied higher than the carotid 

 tubercle, it would be well always to supplement the above test by the method of 

 "lateral compression" (Rouge), — i.e., by pressing together between the thumb and 

 fingers the anterior portion of the relaxed sterno-mastoid muscle and the carotid 

 sheath and its contents. This avoids all risk of coincident compression of the verte- 

 bral, and if it arrests the temporal pulse without affecting materially the bleeding or 

 the pulsation on account of which the examination is made, it greatly increases the 

 probability that the latter are of vertebral origin (Matas). The importance of making 

 the diagnosis is shown by the fact that in sixteen out of thirty-six cases of injuries to 

 the vertebral artery the common carotid had been ligated, aggravating the hemor- 

 rhage by increasing the strain on the vertebral circulation and, of course, also increas- 

 ing the risk from shock, and later from cerebral complications (Matas). 



Ligation of the vertebral has been effected through variously placed incisions : 

 I. Low in the neck, one of three inches in length along the posterior border of the 

 sterno-mastoid and with its lower end at the clavicle, with division of some of the clav- 

 icular fibres of that muscle and of the deep fascia, will permit the recognition of the 

 carotid tubercle, the displacement inward of the sterno-mastoid and internal jugular 

 vein, the definition of the space between the scalenus anticus and the longus colli, 

 and the identification of the artery by its pulsation. The vertebral vein lies in front 

 of the artery. The pleura, the inferior thyroid vessels, the phrenic nerve, and on the 

 left side the thoracic duct must be avoided. The fibres of the cervical sympathetic 

 will be almost necessarily disturbed, and may be included in the ligature. Contrac- 

 tion of the corresponding pupil through the then unopposed action of the oculo- 

 motor, will indicate that the vessel has been secured; it will be only temporary. 



2. For a ligation in continuity, as for wound or aneurism in the suboccipital 

 region, the artery may be much more easily reached through an incision identical 

 with that used for ligating the common carotid above the omo-hyoid (page 732). 

 When the carotid sheath is well exposed it is drawn outward with its contents. 

 Chassaignac's tubercle is felt (on the cricoid level or one centimetre above it) and 

 the loi%us colli fibres below, overlying the artery, are seen. A transverse division 

 of that muscle exposes the vertebral artery in a much safer region than below and at 

 a less depth (Dawbarn). 



The collateral circulation is very freely re-established through the vessels of the 

 circle of Willis. 



