A significant proportion of patients presenting to the emergency department have cervical spinal trauma. This can result from road traffic accidents, blunt injuries and high degree falls and present with a multitude of clinical findings ranging from asymptomatic or minor reversible neurologic injury to severe irreversible deficits and even death.
Advanced trauma life support (ATLS) protocol is followed for the management of trauma patients. Airway maintenance and cervical spine protection constitute the first step of this ATLS algorithm. After trauma cervical spine is considered injured until proven otherwise.
Confident exclusion of cervical spinal injuries requires a thorough evaluation of the mechanism of trauma and patient clinical profile with clinical decisions on whether imaging is required or not. In alert and stable patients two validated decision rules, the National Emergency X-Radiography Utilization Study (NEXUS) criteria Table 1 or the Canadian C spine rule Table 2 [4] are used for excluding patients who do not require cervical spine imaging thereby greatly increasing the sensitivity of injury detection.
Table 1: NEXUS Criteria
Table 2: Canadian C spine rule
If these clinical criteria cannot be applied imaging is performed. Radiologists play an important role in ascertaining the presence and type of injury, defining characteristics, spinal stability, and assessing the prognostic values and treatment options.
CHOOSING AN IMAGING MODALITY
A common debate question in patients with cervical trauma is whether there is still a role for the traditional radiograph compared to CT.
Radiographs with two or three film projections (anteroposterior, lateral and open-mouth odontoid view) have been used since time immemorial for cervical spinal assessment. However, their low sensitivities, especially in patients with non-displaced injuries and those with significant overlying degenerative changes, has resulted in CT largely replacing it in the emergency setup.
As most patients with cervical injuries present clinically in an unconscious and unstable state, the acquisition of radiographs is either not possible or inadequate. Furthermore, Nunez et al found a high rate of missed injuries with conventional radiography (sensitivity 43 %) as compared to CT (sensitivity 98.5%) [3].
The major drawback of CT is its greater level of radiation exposure especially to the radiosensitive thyroid and increased cost, However, significant series of studies have found a very low risk to benefit ratio with higher diagnostic accuracy of CT.
Today, MDCT with its multiplanar reconstruction and three-dimensional volume rendering is the investigation of choice in patients with cervical spine injuries with high validated superiority over conventional radiographs.
APPROACH TO CERVICAL SPINAL EVALUATION IN TRAUMA PATIENTS:
Trauma patients are systematically reviewed based on their clinical profile and imaging features. Patients are classified into two broad groups
The stepwise approach includes the following:
- Identifying low and high-risk groups for spinal injury combining both the type of trauma and patient risk factors Table 3.
Table 3: High and Low risk Groups
- Using NEXUS or CCSR decision-making rules for determining patients who need imaging Table 1 and Table 2.
- Cervical spine imaging evaluation using the ABCS protocol Table 4 and identifying the Mechanism of injury Table 5. [4]
Table 4: ABCs approach to cervical spine imaging evaluation.
Table 5: Mechanism of Injuries
A - Alignment & Anatomy
B - Bony integrity
C - Cartilage (Joint) spaces
S - Soft Tissues
A - Alignment & Anatomy
Draw and look for disruption of 4 lines labeled in Fig. 1
- Anterior vertebral body line.
- Posterior vertebral body line.
- Spinolaminar line
- Prevertebral line
Fig. 1: Spinal lines
B – Bony abnormalities
Cortical discontinuity
Overt fracture lucencies/deformities
Disruption of the ring of C1.
Odontoid fractures
C – Cartilage (Joint) abnormalities
Widened or narrowed disc space/facets
S – Soft tissue abnormalities
Widened prevertebral space
>7mm at C2 level and > 22mm at C7 level - High risk of injury
Several classification systems are used for cervical spinal trauma evaluation divided between the upper and subaxial cervical spine. These include Allen and Ferguson, AO classification, Denis’s ‘3 column concept’ and a novel four-column approach by Moore et al. [1].
Before proceeding to next section, we should probably look upon various UNSTABLE FRACTURES in cervical spine trauma patients [2] -
UNSTABLE FRACTURES |
FLEXION |
- Bilateral interfacetal dislocation
- Flexion teardrop fracture
- Wedge fracture with posterior ligamentous rupture Fig. 6, Fig. 13
Fig. 13: Axial (A), Sagittal (A), and 3D reconstructed VRT(C) CT images, show-
A (Alignment) – Disruption of spinolaminar and posterior spinous lines
B (Bones) – Fracture of lamina of C4 and C5(red arrows). There is anterior wedge fracture of C6 vertebral body with mild posterolisthesis of C6 over C7 (green arrow)
C (Cartilage) – IVD spaces and facetal joints (yellow arrows) appear normal.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
|
EXTENSION |
- Odontoid fracture type II and III
- Hangman's fracture
- Extension teardrop fracture
|
COMPRESSION |
- Burst fracture, e.g. Jefferson fracture
|
ROTATIONAL |
Fig. 14: ROTATIONAL INJURY - Coronal (A), axial (B and C), and 3D reconstructed VRT(D) CT images, show-
A (Alignment) – Alignement not maintained
B (Bones) – Fracture of pedicle of C4, C5 vertebral bodies with involvement of vertebral foramen(red arrows).
C (Cartilage) – IVD spaces appear normal.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
|
SPECIFIC INJURIES -
HANGMAN'S FRACTURE
- Traumatic Spondylolisthesis of C2.
- Fracture of the bilateral pars interarticularis of C2 with anterolisthesis of C2 over C3.
- Best evaluated on lateral view Radiograph and Saggital CT sections
- Disruption of the anterior and posterior vertebral body line.
Fig. 7: HANGMAN'S FRACTURE - Sagittal plain radiograph (A), and sagittal CT image(B), shows
A (Alignment) – Disruption of the anterio and posterior cortex lines with maintained spinolaminar lines
B (Bones) - Spondyloptosis of C2 over C3 (red arrows)
C (Cartilage) – Disruption of intervertebral disc space and facetal joints at C2-C3 level.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
JEFFERSON FRACTURES
- Burst fracture of C1 (atlas) vertebra due to axial unloading along skull vertex to occipital condyles and lateral masses of C1 with disruption of anterior and posterior arches.
- Disrupted alignment of spine at C1 vertebra.
- Fractures of anterior and posterior arches and lateral masses with/without displacement.
- Cervicocranial prevertebral swelling
Fig. 16: JEFFERSON'S FRACTURE - Coronal (A and B), and axial (C) CT images, show-
A (Alignment) –Disruption of spinolaminar line.
B (Bones) – Linear fracture of posterior arch of C1 vertebra (red arrows).
C (Cartilages) – IVD spaces appear normal
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal
ODONTOID FRACTURES
- There are 3 types of fracture patterns based on the Anderson and d’Alonzo classification-
Type I: Fracture of tip of dens. Fig. 9 and Fig. 10
Fig. 9: Type 1 odontoid fracture – Sagittal (A) and coronal (B) CT images, show-
A (Alignment) – Disruption of the anterio and posterior cortex lines with maintained spinolaminar and posterior spinous lines
B (Bones) – Linear fracture of tip of odontoid process of C2 vertebra with mildlly anteriorly displaced fractured fragment (red arrows)
C (Cartilage) – IVD spaces and facetal joints appear normal.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
Fig. 10: Type 1 odontoid fracture – Sagittal (A), coronal (B) and axial (C) CT images, shows
A (Alignment) – Disruption of the anterior and posterior cortex lines with maintained spinolaminar and posterior spinous lines
B (Bones) – Linear fracture of tip of odontoid process of C2 vertebra with anteriorly displaced and angulated fractured fragment (red arrows)
C (Cartilage) – IVD spaces and facetal joints appear normal.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
Type II: Transverse fracture at the dens-body junction Fig. 11
Fig. 11: Type II odontoid fracture – Sagittal (A) and coronal (B) CT images, show-
A (Alignment) – Disruption of the anterior and posterior cortex lines with maintained spinolaminar and posterior spinous lines
B (Bones) – Fracture of odontoid process at dens-body junction of C2 vertebra with anteriorly displaced and angulated fractured fragment (red arrows)
C (Cartilage) – IVD spaces and facetal joints appear normal.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
Type III: oblique fracture into cancellous body of C2. Fig. 12
Fig. 12: Type III odontoid fracture – Sagittal (A), Axial (B) and coronal (C) CT images, show-
A (Alignment) – Disruption of the anterior and posterior cortex lines with maintained spinolaminar and posterior spinous lines
B (Bones) – Fracture of odontoid process with fracture of C2 vertebral body with anterioinferiorly displaced fractured fragment (red arrows)
C (Cartilage) – IVD spaces and facetal joints appear normal.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
- Type II and III are usually unstable fractures.
- Alignment may be maintained or disrupted.
- Isolated fractures - dens and C2 vertebral body.
- IVD spaces and factual joints - may/may not be involved.
UNILATERAL INTERFACETAL DISLOCATIONS
- Hyperflexion-Rotation injury - Stable fractures, displaced facet adds to the stability.
- Superior facet dislocated superior (Incomplete dislocation - perched facet) and anterior to the adjacent inferior facet (Complete dislocation - jumped/locked facets).
- Perched facet - HAMBURGER/REVERSE HAMBURGER BUN SIGN on axial CT images. Fig. 5
Fig. 5: UNILATERAL FACETAL DISLOCATION - Axial CT image showing classical HAMBURGER SIGN in perched facetal joint dislocation with fracture of facet.
- Alignment lost usually.
- Anterior dislocation of superior vertebral body over the inferior vertebral body
- Unilateral facetal joint dislocated
- Associated fractures of facetal processes may be seen.
Fig. 2: Sagittal plain radiograph (A), and sagittal CT image(B), shows
A (Alignment) – Discontinuity of anterior, posterior vertebral lines and spinolaminar lines
B (Bones) - Anterolisthesis of C5 over C6 (yellow arrow) with perched unilateral facet joint with small chip fracture of inferior facet of C5 (red arrows) with fracture of spinous process of C6 vertebra (blue arrow) - UNILATERAL FACETAL DISLOCATION
C (Cartilage) – Decreased intervertebral disc space between C5-C6.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
Fig. 6: Sagittal CT images(A, B, C) show-
A (Alignment) – Discontinuity of anterior, posterior vertebral lines
B (Bones) - Anterolisthesis of C6 over C7 with wedge fracture of C7 vertebra (red arrow) with locked facetal joint (blue arrow) with chip fracture of superior articular facet of C7 vertebra (yellow arrow) - UNILATERAL FACETAL JOINT DISLOCATION
C (Cartilage) – Reduced IVD space with dislocation of facetal joint.
S (Soft tissues) – Qwidening of prevertebral space with air foci noted (green arrow)
BILATERAL INTERFACETAL DISLOCATIONS
- Predominantly a soft tissue (ligament) injury - Completely unstable.
- Alignment lost
- Anterior dislocation of superior vertebral bod
- Bilateral facetal joints dislocated
Fig. 4: BILATERAL FACETAL JOINT DISLOCATION - Sagittal CT image(A), Coronal CT (B), and axial CT (C) images show-
A (Alignment) – Discontinuity of anterior, posterior vertebral and posterior spinous lines
B (Bones) - Anterolisthesis of C6 over C7 (green arrow) with perched bilateral facet joints (red arrows) with fracture of left lateral mass of C7 vertebra involving foramen transversarium (yellow arrow) with fracture of vertebral body (blue arrow)
C (Cartilage) – Dislocation of bilateral facetal joints. (Red arrows)
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear widened.
CLAY SHOVELER FRACTURE
- Fracture of spinous process of lower cervical or upper thoracic vertebra.
- Disruption of spinolaminar or posterior spinous line.
- Fracture involving posterior elements of lower cervical vertebra.
Fig. 21: CLAY SHOVELER FRACTURE - Sagittal (A), and axial CT image(B), shows
A (Alignment) – Discontinuity of spinolaminar and posterior spinous lines
B (Bones) - Comminuted fracture of right lateral mass, bilateral lamina and spinous process of C7 vertebra (red arrows).
C (Cartilage) – C6-C7 facetal joint dislocation with fracture.
(Soft tissues) – Fat planes lost in paravertebral soft tissue.
TEARDROP FRACTURE
- Extreme flexion or extension with axial loading/ compression.
- Anteroinferior aspect of the vertebral body forms teardrop fragment with larger posterior part displaced backward into the spinal canal.
- Disruption of alignment
- Fracture of vertebral body with antero-inferior teardrop fragment.
- Facetal joints dislocation and IVD space narrowing common.
Fig. 3: TEARDROP FRACTURE - Sagittal CT image, shows
A (Alignment) – Discontinuity of anterior and posterior vertebral lines.
B (Bones) - Comminuted fracture of C7 vertebral body with anteriorly displaced tear drop fragment from anteroinferior aspect of vertebral body(blue arrow) and posterior displacement of large posterior part of vertebral body into the spinal canal (red arrow).
C (Cartilage) – Decreased IVD space between C6-C7 and C7-T1.
S (Soft tissues) – Widening of prevertebral space at C7 level
Fig. 20: TEARDROP FRACTURE - Sagittal (A) and axial (B) CT image, shows
A (Alignment) – Discontinuity of anterior, posterior vertebral lines, spinolaminar and posterior spinous line.
B (Bones) - Comminuted fracture of C7 vertebral body with anteriorly displaced tear drop fragment from anteroinferior aspect of vertebral body(red arrows) and posterior displacement of large posterior part of vertebral body into the spinal canal (blue arrow). There is associated comminuted fracture of posterior elements of C7 verterba (yellow arrows) and wedge fracture of anterior end plate of T1 vertebra (green arrow).
C (Cartilage) – Decreased IVD space between C6-C7 and C7-T1.
S (Soft tissues) – Widening of prevertebral space at C7 level with fractured fragments in prevertebral space.
BURST/COMPRESSION FRACTURES
- Loss of vertebral body height without evidence of distraction or translation
- Retropulsion of fracture fragment into spinal canal.
- Disruption of anterior or posterior vertebral body line.
- Fracture of vertebral body
- IVD space or facetal joint disruption common.
Fig. 8: COMPRESSION/BURST FRACTURE - Sagittal plain radiograph (A), and sagittal CT image(B), shows
A (Alignment) – Discontinuity of anterior, posterior vertebral and spinolaminar lines
B (Bones) - Anterolisthesis of C4 over C5 (blue arrow) with locked bilateral facetal joints (green arrows). Sagittal CT image (B) of the same patient shows the C4 burst fracture. Additionally a small posterior retropulsed fracture fragment is seen within the spinal canal (red arrow), which is missed on plain radiograph.
C (Cartilage) – Decreased intervertebral disc space between C4-C5 and bilateral facetal dislocation.
S (Soft tissues) – Prevertebral and paravertebral soft tissue appear normal.
Fig. 15: COMPRESSION FRACTURE WITH ROTATIONAL/HYPERFLEXION INJURY- Coronal (A), axial (B and C), and 3D reconstructed VRT(D) CT images, show-
A (Alignment) –Disruption of alignment of cervical spine.
B (Bones) – Comminuted fracture of C6 vertebral body with superiorly displaced right fractured fragment (yellow arrows), and inferiorly displaced left fractured fragment (red arrows), which are seen lying adjacent to C5 and C7 vertebral bodies. There is associated fracture of pedicle of C4, C5 vertebral bodies (blue arrows)
C (Cartilages) – Disruption of C5-C6 and C6-C7 IVD space.
S (Soft tissues) – Prevertebral and paravertebral soft tissue show swelling in form of loss of fat planes.