Prompt diagnosis of cervical spine (C-spine) injuries is imperative to provide early treatment and prevent secondary spinal cord injury. Motor vehicle collisions account for the majority of spinal cord injuries followed by falls and acts of violence (i.e., gunshot wounds).1 Cervical spine injuries are found in 2% to 3% of blunt trauma patients that undergo imaging.2 The cervical spine is the most common location in the spine to be injured, accounting for upward of 60% of cases.1,3 Unfortunately, a delay in diagnosis occurs in one-quarter of cases. Approximately 3% of malpractice claims are related to fractures of the spine, and these claims account for almost 10% of dollars paid.
The upper cervical spine consisting of the occiput, C1 (atlas), and C2 (axis) is unique from the remainder of the cervical spine. It is designed to allow for rotation of the head. The C1 vertebra is a ring structure that articulates with the occiput. The C2 vertebra is composed of a body with a bony projection (dens) that goes through the anterior portion of the ring of C1. The dens is stabilized by both the transverse and alar ligaments (Fig. 9–1). The transverse ligament is located along the posterior surface of the dens, attaching on either side of C1. Injury to this ligament may be catastrophic to the patient in the form of atlantoaxial instability and a high cervical cord lesion.
The transverse and alar ligaments and their importance in stabilizing the C1 and C2 vertebrae.
The lower cervical spine can be divided into two columns, where disruption of an entire column is required to alter stability.4 The anterior column consists of the anterior and posterior longitudinal ligaments and the vertebral body. The posterior column comprises the pedicle, lamina, articular facet joints, and ligamentum flavum.
Not all patients with a traumatic source of neck pain will require imaging. Two groups have attempted to safely reduce the rate of imaging of the cervical spine in the setting of trauma based on the absence of high-risk criteria.5,6 The National Emergency X-Radiography Utilization Study (NEXUS) group consisting of 34,069 patients identified five criteria that were 99.6% sensitive in excluding a clinically significant cervical spine injury (Table 9–1). The Canadian C-spine rule detected 100% of 151 clinically significant C-spine injuries in 8924 patients. In this rule, to be considered for exclusion from needing C-spine radiographs, patients must have a Glasgow Coma Scale of 15 and have no high risk features (age greater than 65, dangerous mechanism, or extremity paresthesias). Next, low risk factors are assessed. In patients with a low risk factor (simple rear-end MVC, sitting in ED, ambulatory at any time, delayed onset of neck pain, or absence of midline C-spine tenderness) neck rotation is tested. If they are able to actively rotate the neck 45 degrees to the left and right, no radiographs are needed.6
TABLE 9–1Nexus Criteria to Clinically Exclude a Cervical Spine Fracture ||Download (.pdf) TABLE 9–1 Nexus Criteria to Clinically Exclude a Cervical Spine Fracture
|If all five items are met, imaging is not performed. |
When NEXUS criteria were applied to the Canadian C-Spine Rule data set, the sensitivity of NEXUS criteria was 92.7%.7 In a prospective cohort study (in Canadian emergency departments), the Canadian C-spine Rule had higher sensitivity (99.4% vs. 90.7%) and specificity (45.1% vs. 36.8%) versus the NEXUS criteria and would have led to a reduction in radiography rates, although patient populations were different between the two studies.8
Plain radiographs have historically been used as a screening test for cervical spine injury. The typical trauma series includes an anteroposterior (AP), an open-mouth (odontoid), and a lateral view. The plain radiographs detect approximately 65% to 75% of injuries and should include the C7-T1 junction because a high number of injuries occur at C7.9–12 In the polytrauma unconscious patient, the sensitivity and adequacy of plain films is reduced and has little role, making computed tomography (CT) the imaging test of choice.12 Flexion-extension radiographs are controversial and not performed routinely, especially when CT and magnetic resonance imaging (MRI) are available.
The interpretation of plain radiographs is addressed in this chapter when discussing each injury; however, the clinician should have a systematic approach to avoid missing important injuries. Before beginning, assess the adequacy of the films, specifically whether the open-mouth view allows visualization of the dens and lateral masses and whether the lateral view demonstrates all of the cervical vertebrae and the top of T1. Next, consider the alignment of the vertebrae on the lateral view (Fig. 9–2). Look closely for any fractures of the vertebral bodies or posterior bony structures. Loss of height of a vertebral body suggests a compression fracture. An abnormal angle between vertebral bodies suggests an unstable fracture. Finally, evaluate the prevertebral soft tissues and the predental space (Fig. 9–3).
Loss of alignment of the anterior and posterior vertebral body line or the spinolaminar line suggests an unstable injury.
In adults, the prevertebral soft tissues should be <7 mm at C2; <5 mm at C3; and <22 mm at C6. In children, 14 mm is the acceptable limit at C6.
Because plain radiographs are less sensitive and frequently inadequate at demonstrating the entirety of the cervical spine, CT scan of the cervical spine is the more common initial imaging study of choice in trauma patients. The sensitivity for detecting injuries is 97% to 100% and the specificity is 99.5%.13–17 A negative CT scan that includes sagittal reconstructions has been shown to exclude both fracture and clinically significant ligamentous injury even in patients with persistent neck pain.18 Cervical spine immobilization can often be discontinued with a normal CT at the discretion of the physician.12,16 In addition, when a fracture is seen on plain radiographs, CT is useful to further define the traumatic injury. MRI is useful for soft tissue, ligamentous, disk, or spinal cord injuries but is poor for detecting osseous injuries. Additional disadvantages include a high false-positive rate in trauma and obvious time and patient access constraints in the emergency setting.12,16,17 Isolated clinically significant cervical spine or ligamentous injury with a negative CT is extremely rare.16
Neurogenic shock occurs most commonly after cervical spine injury (19% of patients), followed by thoracic (7%) and lumbar (3%) injuries. Vital signs demonstrate a low systolic blood pressure (<100 mm Hg) and bradycardia (<60–80 beats/min). These abnormalities usually occur several hours after cord injury. The pathogenesis is related to loss of sympathetic tone and decreased peripheral vascular resistance. Bradycardia is present because the disruption of sympathetic activity to the heart resulting in unopposed vagal activity. Neurogenic shock should be distinguished from the term “spinal shock,” which refers to an initial loss with a gradual recovery of some neurologic function after a spinal cord injury.
Knowledge of the location of nerve tracts within the spinal cord will help the clinician understand the syndromes that occur after injury (Fig. 9–4). A patient with a complete cord syndrome will present early with flaccid paralysis and loss of sensation below the injury. Reflexes are absent and there will be no response to the Babinski test. Priapism may appear and generally lasts for a day. Within 1 to 3 days, hyperactive reflexes, a positive Babinski, and spasticity develop reflecting the upper motor neuron injury.
The anatomy of a cross section of cervical spinal cord.
Incomplete cord injury is usually more challenging to diagnose. Several classic variants exist, but there is significant disparity in presentation. The anterior cord syndrome occurs in most cases from hyperflexion of the cervical spine. The anterior two-thirds of the cord are affected but the dorsal columns, controlling light touch, proprioception, and vibratory sense, are spared to a variable degree (Fig. 9–5A). Central cord syndrome is due to hyperextension injury and occurs frequently in patients with preexisting cervical degenerative joint disease. In this setting, the central portion of the cord is compressed between the ligamentum flavum and bony osteophytes. Clinically, the patient will exhibit motor impairment that is greatest in the upper extremities with variable amounts of sensory loss and bladder dysfunction (Fig. 9–5B). Finally, the Brown-Sequard syndrome is a rare condition due to unilateral loss of cord function from hemisection of the spinal cord (Fig. 9–5C). The patient will exhibit paralysis with loss of proprioception, vibration, and light touch on the side of the damage and loss of pain and temperature sensation on the contralateral side.
Incomplete spinal cord syndromes. A. Anterior cord. B. Central. C. Brown-Sequard.
Neurogenic shock should be considered in the patient with hypotension, bradycardia, and traumatic spinal cord injury once other causes of shock have been excluded. There is no consensus on the optimal treatment of neurogenic shock. Crystalloid fluid infusion and cervical stabilization may be all that is necessary in mild cases. Pressors are indicated if vascular instability persists.
In patients with blunt traumatic spinal cord injury, high-dose steroids were considered as a treatment option early postinjury.19,20 Even within the recommended 8-hour window, steroids carry a significant incidence of complications such as sepsis and pneumonia. In addition, the evidence for the efficacy of steroids to produce a small gain in the total motor and sensory score was seen only in a post-hoc analysis. This fact increases the likelihood that a statistical difference will be found when one does not exist and generally precludes the results from being used to change clinical practice.21 Therefore, without compelling evidence for the efficacy of a high-dose steroid regimen, many feel that steroids should be used with caution or not at all.22,23 Several medical societies have stated that this treatment is not a “standard of care” and recent literature recommends not using steroids in spinal cord injury as the risk of harm outweighs the potential benefit.24,25
The cervical spine is divided into two segments for the purposes of this chapter. High cervical spine injuries are those that involve the occiput, C1, and C2. The remainder of the chapter focuses on injuries to the third through seventh cervical vertebrae. This discussion categorizes injuries based on the mechanism of injury. Clinical stability of each injury is discussed. Loss of stability refers to the inability of the spine to maintain relationships under normal physiologic loads. With instability comes the inherent risk of secondary spinal cord injury if spinal immobilization is not adhered to.