h1 class=”calibre8″>10 Subaxial Cervical Trauma in the Adult Patient
Abstract
This chapter on subaxial cervical trauma in the adult patients will address the principles of understanding such injuries as well as focus on the efficient diagnosis and management. Subaxial cervical trauma is common and is defined as an injury that occurs from C3 to C7. Failure of identifying subaxial cervical trauma on initial evaluation may result in delayed treatment and devastating spinal cord injury. Such injuries are commonly seen in practice and it is important to understand the epidemiology, clinical and diagnostic features, and treatment options required to provide optimal care.
Keywords: subaxial cervical spine trauma, epidemiology, classification, diagnosis, treatment
10.1 Epidemiology
Subaxial cervical spine trauma accounts for 2 to 3% of injuries sustained by blunt trauma, 1,2 and is found in 21% of patients with traumatic spinal injury. 3 In North America, approximately 150,000 people per year suffer from cervical spine injuries. Of those, around 11,000 also suffer from spinal cord injuries. 2 Approximately 75% of all blunt cervical spine injuries occur in the subaxial cervical spine 4 with 50% of the injuries located between the levels C5 and C7. 5 Several studies have found a bimodal distribution of injuries with an increased risk of injury in young males (ages 15 to 45 years) as well as in older males and/or females (ages 65 to 85 years). Elderly females are four times more likely to suffer spinal trauma in comparison to their male counterparts. 3 Motor vehicle accidents account for a large percentage of cervical spine injuries and tend to occur in younger individuals whereas older individuals tend to have injuries that result largely from ground-level falls. 3
10.2 Initial Management
The importance of recognizing potential subaxial cervical spine trauma cannot be overlooked. A standardized clinical and radiographic evaluation is paramount to prevent worsening of such injuries and the devastating sequelae that can result due to misdiagnosis. Following stabilization, as guided by the Advanced Trauma Life Support algorithm, patients with concern for cervical spine injury should be placed in a rigid cervical collar. Collars should be sized and fitted appropriately to ensure immobilization. All patients should be log rolled with cervical spine precautions during the secondary survey to prevent further injury. Outward signs of trauma to the head, neck, and upper torso can hint to the mechanism of injury during the traumatic event.
In addition, inspection of cervical posture for malalignment, including angular or rotational, can hint to dislocation or subluxation. 5 After completion of the primary and secondary survey, a detailed history can be of aid to determine risk factors as well as energy patterns for those who sustain subaxial cervical spine trauma. History of ankylosing spondylitis, diffuse idiopathic skeletal hyperostosis (DISH), or connective tissue disorders that are associated with ligamentous hyperlaxity should be identified as it increases the risk of subaxial cervical spine trauma. 5 A thorough physical exam should be performed on all patients with suspected subaxial cervical spine injuries including palpation of the entire spine with focus on tenderness and evaluation for any “step-offs” that could be present. Assessment and evaluation of each muscle group and sensory distributions can help identify levels of potential injury. Continuing to perform subsequent and frequent neurological exams is necessary, especially when spinal cord injury is evident because it allows for determination of injury progression versus symptom improvement.
10.2.1 Diagnostic Imaging
Subaxial cervical spine injuries are often misdiagnosed. Thus, understanding the various types of imaging modalities that can be utilized to diagnose such injuries is important. This can significantly reduce the number of unnecessary diagnostic images obtained that demonstrate negative findings. Obtaining the correct diagnostic imaging will expedite diagnosis and proper care of the injured patient.
Multiplanar computed tomography (CT) scans of the cervical spine have become the imaging modality of choice in the initial work-up of trauma patients. They have a sensitivity and specificity of 99 and 100%, respectively. In comparison, plain radiographs of the cervical spine have a sensitivity ranging from 43 to 70%. 6,7 CT scans are rapidly accessible and provide sufficient information in a timely fashion, which is necessary for accurately diagnosing severe injuries that require emergent intervention. Although ligamentous injuries cannot be fully assessed by CT scans, recent studies have suggested a CT scan with sagittal and coronal reconstruction is sufficient for diagnosis and further imaging is not warranted. 5
The role of magnetic resonance imaging (MRI) has been controversial because despite its high sensitivity, it has a low specificity, which can lead to false positive results. 5 Nonetheless, MRI provides detailed information regarding the discoligamentous complex (DLC) as well as subaxial instablility. 5 The role of MRI was found to be important in older patients more than 60 years of age, and in patients that are obtunded, have cervical spondylosis, polytrauma, and patients with neurological deficits. These were noted to be predisposing factors for further injuries that were missed on CT scan but identified on MRI. 8 Kaiser et al described that with the resolution of CT scans increasing, the rate of missed clinically significant injuries remains at 6%. 9 It is impossible to predict patients who have occult injuries when CT scan of cervical spine is negative, even when a minor mechanism of injury may be responsible. The authors concluded that all blunt trauma patients with altered mental status should continue to undergo MRI for adequate cervical spine clearance even with a negative CT scan. 9 In contrast, Khanna et al concluded that the use of MRI for cervical spine clearance adds little information with the presence of a negative CT scan and a normal neurological examination. 10 The authors did state that MRI may have a role on a delayed basis in patients with persistent neck pain. 10
10.2.2 Cervical Traction
Prompt reduction with cervical traction is of utmost importance for patients with cervical dislocation. Early reduction results in decompression of the spinal canal in patients with neurological impairments and helps to obtain alignment prior to surgery. 11 Traction is not warranted for the management of extension-distraction injuries as this may lead to worsening deformity and risk for neurological compromise. 12 With traction, realignment of up to 70% of cervical dislocations can be achieved. 13 A retrospective review of 53 patients with cervical facet dislocations showed that closed reduction was achieved in 90% of patients by using a combination of traction, positioning, and occasional manipulation. Of this group, 68% had significant neurological improvement. 14
Cervical traction can be safely done after admission to the intensive care unit to limit transport once completed. Patients should be given adequate pain control and light sedation to tolerate the procedure while maintaining responsiveness to participate in neurological exams during manipulation. Gardner–Wells tongs may be applied, and traction can be performed in the flexion, extension, or neutral positions depending on placement in relationship to the pinna. 11 Approximately 5 pounds of weight should be added per level of injury. Any manipulation requires subsequent close clinical and radiological observation to avoid overdistraction and further neurological injuries. In the setting of unilateral locked facets, the surgeon can reduce the injury by flexing and rotating the cervical spine. The manipulation can only be done in patients with a reliable neurological exam. 15 Once reduced, cervical extension and lighter traction should be maintained to prevent loss of reduction.
The surgeon should avoid traction in patients who are obtunded, inebriated, sedated/intubated, or unable to comply with a neurological exam. 15 In these situations, intraoperative or open reduction may be necessary. Contraindications include rostral injuries, such as atlantoaxial or occipital cervical dislocations. 16 MRI prior to closed reduction can be used to identify traumatic cervical disc herniation, but ultimately delays spinal decompression. Early reductions have the potential to improve neurological function and should always be attempted in a timely fashion. 15
10.3 Classification
A myriad of classification systems has been used to aid in the decision-making process for subaxial cervical trauma. Earlier classification systems relied on plain radiographic imaging as well as mechanisms of injury. These early classification systems did not, however, factor in the patient or the patient’s neurological status.
10.3.1 Classification Systems
One of the first universally accepted classification systems for indirect, lower cervical spine fractures and dislocations was described by Allen et al in 1982. 17 The Allen–Ferguson system focused on the mechanism of injury which could be extrapolated from plain radiographic images. The system was generated from a retrospective analysis of 165 patients with closed, indirect fractures and dislocations of the lower cervical spine. Injuries were classified into six categories which included flexion-compression, vertical compression, flexion-distraction, extension-compression, extension-distraction, and lateral flexion. Each of these categories were further divided into subcategories, which correlated to the severity of injury. This classification system was modified by Harris et al in 1986 and focused on rotational rather than distractive forces. 18 The categories in the Harris system included flexion, flexion-rotation, hyperextension-rotation, vertical compression, extension, and lateral flexion.
The AO Classification System
In 1994, Magerl et al described a classification system for thoracolumbar spine injuries, which was commonly applied to cervical spine injuries and primarily relied on pathomorphological criteria and plain radiographic imaging. 19 Classification criteria included the main mechanism of injury and pathomorphological uniformity as well as consideration of prognostic aspects regarding healing potential. The AO system classified injuries as type A (axial force resulting in vertebral body compression), type B (anterior and posterior element injuries with distraction), and type C (anterior and posterior element injuries with rotation; ▶ Table 10.1). 19 The AO subaxial cervical spine injury classification system did provide adequate reliability and was thought to be a valuable tool for communication, patient care, and research purposes. 20
Type | A | B | C | ||||||
Group | A1 | A2 | A3 | B1 | B2 | B3 | C1 | C2 | C3 |
Subgroup | A1.1 | A2.1 | A3.1 | B1.1 | B2.1 | B3.1 | C1.1 | C2.1 | C3.1 |
A1.2 | A2.2 | A3.2 | B1.2 | B2.2 | B3.2 | C1.2 | C2.2 | C3.2 | |
A1.3 | A2.3 | A3.3 | B2.3 | B3.3 | C1.3 | C2.3 | |||
Source: Magerl et al. 19 | |||||||||
Subaxial Injury Classification System
The Subaxial Injury Classification (SLIC) System and injury severity score was developed based on weaknesses of previous classification systems. 21 As discussed, previous systems were developed based solely on the force vectors extrapolated from the injury patterns seen on plain radiographic films. Vaccaro et al describes the importance of incorporating both neurological status and emphasis on the stability of different injuries. 21 It allows the physician to account for three major characteristics to assist in decision-making, which include injury morphology, integrity of the DLC, and the neurological status of the patient. 22 These three factors are evaluated independently and the summation provides a final score which can assist in management. SLIC is one of the most widely used systems today and is summarized in ▶ Table 10.2. 21
Points | |
Injury morphology | |
| 0 |
| 1 |
| +1 |
| 2 |
| 3 |
Integrity of the DLC | |
| 0 |
| 1 |
| 2 |
Neurologic status | |
| 0 |
| 1 |
| 2 |
| 3 |
| +1 |
Score | Treatment |
≥ 5 | Operative |
4 | Operative vs. nonoperative |
≤ 3 | Nonoperative |
Abbreviation: DLC, discoligamentous complex. Source: Vaccaro et al. 21 | |
Many believe that the SLIC system can be integrated with daily practice and can be easily applied while remaining comprehensive. Studies have also shown that it is reproducible among surgeons. 23 A retrospective analysis of patients previously treated for subaxial cervical spine trauma determined that when the SLIC system was applied, 90% of those patients matched the conservative or surgical approaches that were proposed. 24 However, larger and higher quality evidence that can validate the SLIC system are lacking.
10.4 Nonsurgical Management
In the setting of subaxial cervical spine injuries, nonsurgical management with external immobilization can be considered for injuries that are deemed stable. There is no consensus regarding the types of injuries stable enough for nonoperative treatment. However, the stability of the injury pattern, neurological status of the patient, and the patient’s comorbidities are all factors that should be considered. 5 If using the SLIC system, a score of 3 or less can be considered stable and treated with cervical orthoses. Such management can also be done in patients with a SLIC score of 4. However, the decision for nonoperative versus operative treatment may be based on the surgeon’s experience and patient’s comorbidities. 5
Nonoperative treatment should be restricted to only bony injuries and should not be considered for patients with DLC injuries. 25 Although cervical orthosis is not required in the stable injury, it does emphasize the importance of activity restrictions and provides comfort. 5,15 Cervical orthosis can provide adequate stability in fractures without ligamentous injuries. This varies when it comes to fractures of the cervical facet that are less predictable in terms of instability. In a retrospective series of 68 patients with cervical facet fracture-dislocation injuries, external immobilization could provide stability in injuries with < 1 mm of displacement. 26 Typically, external immobilization for stable fractures is required for at least 6 to 12 weeks with close interval follow-up. Prior to cervical spine clearance, the physician should obtain dynamic plain cervical spine radiographs to rule out evidence of instability. If no abnormalities are present, immobilization can be discontinued.
In patients with ligamentous injuries, the physician should be extremely cautious when foregoing surgical management for external immobilization. A review of 64 patients with subaxial cervical spine injuries strongly correlated the presence of ligamentous injury with or without severe vertebral body injury to failure of nonoperative management. When these injuries were not present, the authors were able to conclude that successful treatment with bracing was achieved. 27 Even after immobilization, pain can persist and instability can continue. Further imaging should be done at that time to determine the burden of injury and evaluate for possible surgical treatment (▶ Fig. 10.1).
Fig. 10.1 (a) Axial computed tomography (CT) scan of the cervical spine showing a left C6 facet fracture extending into the pedicle. Sagittal view also shows extent of fracture without dislocation/distraction or sagittal imbalance. Magnetic resonance imaging (MRI) of the cervical spine stir sequence shows significant posterior ligamentous injury extending from C2 to C7. Decision was made to manage patient nonoperatively with cervical orthosis. (b) Anteroposterior and lateral plain radiographs of the cervical spine completed at 6 weeks follow-up for clearance of cervical orthosis. Images were significant for a left C5–C6 unilateral jumped facet with anterolisthesis of C5 on C6. MRI of the C spine with stenosis and posterior displacement of the spinal cord at the level of injury. (continued)
Related posts:
Traumatic Atlantoaxial Rotatory Fixation
Cranioskeletal Traction for the Management of Trauma to the Cervical Spine
Trauma in Patients with Rheumatoid Arthritis of the Cervical Spine
Penetrating Injuries to the Cervical Spine
Clinical Trials Update: Where Do We Go from Here?
Initial Assessment (Including Imaging) of Cervical Spinal Cord Injury
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