75 - Spine Trauma and Spinal Cord Injury

In the setting of spinal trauma, the bone, ligaments, spinal cord, and vascular structures may be injured. Anatomically, the vertebral bony spine can be divided into structural columns. The cervical spine is traditionally divided into two columns— anterior and posterior. The anterior column consists of the load-bearing vertebral bodies, intervertebral disks, anterior longitudinal ligament, and posterior longitudinal ligament (Fig. 75.1). The posterior column consists of the more posterior structures, including the pedicles, laminae, and transverse and spinous processes (Fig. 75.2). In contrast, the thoracic and lumbar vertebral spines are divided into three columns based on the modified Denis model—anterior, middle, and posterior (Fig. 75.3). The anterior column consists of the anterior longitudinal ligament, the anterior two thirds of the vertebral body, and the intervertebral disk. The middle column consists of the posterior longitudinal ligament, the posterior third of the vertebral body, and the intervertebral disk. Any disruption of the middle column predisposes a patient to significant spinal cord injury because the middle column abuts the spinal canal. The posterior column consists of the remaining posterior structures. The C1 and C2 vertebrae are anatomically unique (Fig. 75.4). C1 (atlas) is a ring-link structure without a vertebral body. It articulates superiorly with the occipital condyles. This articulation allows 50% of normal neck flexion and extension. C2 (axis) projects the dens superiorly to articulate with C1. The transverse ligament tethers the dens to the anterior arch of C1. This atlantoaxial articulation allows 50% of normal neck rotation left and right. The spinal cord spans from the foramen magnum to the L1 level, whereupon the spinal cord tapers into the conus medullaris and cauda equina, a collection of peripheral lower lumbar and sacral nerve roots. Because the spinal cord is thickest in the cervical spine, there is relatively less spinal canal space in the cervical levels than in the thoracic or lumbar spine. Thus spinal cord injuries occur more frequently with cervical spine trauma than with thoracic or lumbar spine trauma. The neurologic dermatomes can help localize the injury (Table 75.1). The vertebral arteries branch off the subclavian arteries and course superiorly within the transverse foramina of C2 to C6. These arteries then merge to form the basilar artery. • Patients with spinal pain and spine fractures should receive a thorough neurologic examination to look for spinal cord injury. • Spine fractures are associated with a high incidence of concurrent noncontiguous spine fractures and spinal cord injuries. • The National Emergency X-radiography Utilization Study criteria or the Canadian Cervical-Spine Rule criteria can be used to identify low-risk patients who do not need cervical spine imaging. • Imaging with plain films versus computed tomography of the cervical spine should be based on the pretest probability of a significant injury and the irradiation risk with computed tomography. • Spinal shock, or transient physiologic transection of the spinal cord as a result of trauma, is different from neurogenic shock, which is physiologic sympathectomy of the upper spinal cord leading to peripheral vasodilation. • Patients with a spinal cord injury caused by blunt trauma are often given high-dose corticosteroids within 8 hours of injury, although such therapy is controversial. KEY POINTS