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Vascular Injuries


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  • Chapter Synopsis

  • Vertebral artery injury during cervical spine surgery is a rare but devastating complication. The vertebral artery is most susceptible to injury anteriorly at C7, laterally from C3 to C7, and posteriorly at C1 and C2. A thorough understanding of normal arterial and osseous anatomy, as well as common aberrancies, can reduce the risk of injury. Despite taking all possible precautions, inadvertent injury to this vessel can still occur, thus making an understanding of treatment options following an injury a necessity for all surgeons performing these procedures. The purpose of this chapter is to review the vertebral normal and anomalous vertebral anatomy, identify points of risk during specific cervical spine procedures, and provide a general treatment algorithm for management of intraoperative vertebral artery injuries.

  • Important Points

  • Normal vertebral artery anatomy includes passage anterior to the transverse foramen of C7 and through the foramina of C3 to C6.

  • The transverse foramen of C2 is an oblique channel through the axis, and the artery courses medially in the vertebral groove on the superior aspect of the atlas.

  • At a distance ranging from 8 to 18 mm from the midline, the artery abruptly changes course, traveling anteriorly and superiorly toward the foramen magnum.

  • In the event of injury, repair should be attempted when possible, with tamponade and angiographic coiling as other potential treatment options.

  • Clinical and Surgical Pearls

  • During anterior spine surgery, the vertebral artery is most susceptible to injury anterior to C7 and laterally from C3 to C7.

  • Posterior C1-C2 transarticular screw fixation (Magerl) has a relatively high reported rate of vertebral artery injury and has largely been replaced by C1-C2 fusion with a screw-rod construct (Harms).

  • Posterior subaxial spine instrumentation has exceedingly low rates of vertebral artery injury, although injury during pedicle screw placement has been reported.

  • Clinical and Surgical Pitfalls

  • Numerous vertebral anomalies can place the vertebral artery at risk if they are not recognized preoperatively.

  • From C3 to C6, the artery is typically protected by the transverse foramen at the level of the uncovertebral joint. However, care should be taken while exposing the C7 uncovertebral joint, given the anterior position of the vertebral artery at this level.

  • The presence of an aberrant entry level of the vertebral artery places it at risk anteriorly at potentially any level if this aberrant anatomy is not recognized preoperatively.

  • During anterior cervical corpectomy, the recommended width of decompression is approximately 16 mm.

Vertebral artery injury during surgical procedures of the cervical spine is a rare but devastating complication. The various procedures commonly performed by spine surgeons place the artery at risk in different ways. The vertebral artery is most susceptible to injury anteriorly at C7, laterally from C3 to C7, and posteriorly at C1 and C2. A complete understanding of normal and aberrant anatomy, strict preoperative evaluation of imaging studies, and meticulous surgical technique can minimize these risks. Despite taking all possible precautions, inadvertent injury to this vessel can still occur, thus making an understanding of treatment options following an injury a necessity for all surgeons performing these procedures. Should an injury occur, implementation of an appropriate treatment algorithm can mitigate the morbidity of this feared complication. The purpose of this chapter is to review the vertebral normal and anomalous vertebral anatomy, identify points of risk during specific cervical spine procedures, and provide a general treatment algorithm for management of intraoperative vertebral artery injuries.

Vertebral Artery Anatomy

The vertebral arteries are branches of the first portion of the subclavian arteries. These paired arteries are generally unequal in size, with the left the larger and dominant of the two. The typical course of the vertebral artery allows for its classic division into four segments: V1 to V4. The first segment (V1) starts with branching of the vertebral artery from the subclavian artery and follows as it courses anterior to the transverse foramen of C7 and into the transverse foramen of C6. The second segment (V2) includes the section of the artery as it passes through the successive vertebral foramina from C6 to C1. V3 comprises the portion from the superior aspect of the arch of the atlas to the foramen magnum, whereas V4 extends from the foramen magnum to the confluence with the contralateral vertebral artery; together, they form the basilar artery ( Figs. 50-1 and 50-2 ).

FIGURE 50-1, Schematic representation of normal vertebral artery anatomy with passage through the transverse foramina of C1 to C6. Note the midline orientation of the longus colli musculature. The inset depicts relationships of the artery within a transverse foramen, most notably with the exiting nerve root and associated uncovertebral joint.

FIGURE 50-2, Coronal reconstruction of a computed tomography angiogram demonstrating normal passage and filling of bilateral vertebral arteries.

Various anatomic relationships throughout the course of the vertebral artery are important to the spine surgeon. In the V2 region, the artery normally remains 1.5 mm or more lateral to the uncovertebral joint. Further, the bony architecture within the region of the V2 segment dictates a mildly convergent course of the arteries through this section; the mean interforaminal distance at C6 is approximately 29 mm compared with 26 mm at C3. Similarly, the mean distance from the medial edge of the longus colli to the medial edge of the vertebral artery decreases from 11.5 mm at C6 to 9 mm at C3. Whereas the transverse foramina of the subaxial spine are ring shaped, the transverse foramen of C2 is an angulated canal bordered by the pedicle and lateral mass. Its inferior and lateral openings allow the artery to deviate 45 degrees laterally before continuing its ascent to enter the transverse foramen of C1.

The V3 segment becomes important to the spine surgeon mostly during the posterior approach to the atlantoaxial joint. As the artery exits the foramen of C1, it travels posteriorly and medially inside the vertebral artery groove on the superior aspect of the atlas. At a distance ranging from 8 to 18 mm from the midline, the artery abruptly changes course, traveling anteriorly and superiorly toward the foramen magnum.

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