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Spine Trauma


INTRODUCTION

Background

  • The majority (80%) of pediatric spine trauma occurs in the cervical spine and annual incidence is 1% to 2%. Pediatric spine trauma is most commonly secondary to motor vehicle accidents (52%), sports injury (27%), falls (15%), and nonaccidental trauma (3%). Spinal trauma from nonaccidental injury is more common in children younger than 2 years of age, while sports-related injuries are more common in older children and adolescents.

  • The overall mortality of pediatric cervical spine injuries is 16% to 18%, with higher mortality associated with upper cervical spine injuries (particularly atlanto-occipital dislocation), younger age, and associated head injury.

  • The pediatric age and associated spine maturity impacts the susceptibility to injury. The pediatric spine reaches a more adult configuration at ∼8 years of age. In children younger than 8 years of age, the majority of injuries occur at C1–C3, while injuries are more common from C5 and below in children older than 8 years of age.

  • Compared to adults, younger children have greater ligamentous laxity, greater head:torso ratio, weaker neck muscles, shallow occipital condyles, developing ossification centers, horizontal facets (upper cervical facet angulation of 30 degrees vs 60–70 degrees in adults; lower cervical spine angulation of 55 degrees vs 70 degrees in adults), absent uncinate processes in children under 10 years old allowing for greater rotational movement, and underdeveloped spinous processes allowing for greater flexion and extension.

Imaging

  • The primary modalities for evaluating cervical spine trauma are radiography, CT, and MRI. Often, all these modalities are used in various combinations for accurately diagnosing spinal trauma.

  • The National Emergency X-Radiography Utilization Study (NEXUS) trial established five high-risk criteria for cervical spine injury in children under 18 years of age: (1) midline cervical tenderness, (2) evidence of intoxication, (3) altered level of alertness, (4) focal neurologic deficit, and (5) painful distracting injury. The presence of any one of the five criteria placed a patient into the high-risk group; the absence of all criteria defined a patient as low risk. Among the low-risk group, no patient suffered a cervical spine injury, indicating that no imaging was necessary in this group. The high-risk group should first undergo AP and lateral spine radiographs. If a child has worsening symptoms and deficits despite negative radiographs, CT or MRI is recommended. However, many institutions bypass radiographs for children with major trauma or neurologic deficits or those who are unconscious.

  • Because there is a greater prevalence of ligamentous injury in children relative to adults, it is important for the radiologist to be knowledgeable of normative values for measurements that can indicate a ligamentous injury and require MRI for direct assessment of the ligaments. It is also important for radiologists to be familiar with the ossification centers and normal physiologic variants in the cervical spine that may be encountered.

  • MRI is the most sensitive technique for identification of spine injury, particularly the spinal ligaments, spinal cord, and soft tissue of the spinal canal. Up to 24% of children with radiographically occult injury had injuries visible on MRI.

  • This section will illustrate the imaging appearance of spinal trauma, with particular emphasis on CT and MRI findings that indicate spinal trauma, as well imaging of uncommon spinal trauma and normal anatomic variants.

REFERENCES

  • 1. Traylor K.S., Kralik S.F., Radhakrishnan R.: Pediatric spine emergencies. Sem Ultrasound CT MR 2018 Dec; 39: pp. 605-617.
  • 2. Huisman T.A., Wagner M.W., Bosemani T., Tekes A., Poretti A.: Pediatric spinal trauma. J Neuroimaging 2015 May–Jun; 25: pp. 337-353.

CRANIOCERVICAL JUNCTION CT MEASUREMENTS

Basion-Dens Interval (BDI). Measured as the shortest distance between the basion and the tip of the ossified odontoid process of C2. Normal <10 mm. Alternatively, the basion-cartilaginous dens interval can be used in children with incomplete ossification.

Atlantooccipital Interval. The largest of five perpendicular measurements between the occipital condyle and C1 on a lateral sagittal image on each side. The anterior intraoccipital synchondrosis should not be in the measurement. Normal < 2.5 mm.

Anterior Atlantodental Interval (ADI). Measured as the distance between the inferior posterior margin of the anterior arch of C1 and the anterior margin of the odontoid process. Normal <2.5 mm.

Atlantoaxial Interval. Measured as the shortest perpendicular distance between the lateral masses of C1 and C2 on each side. Normal <3.9 mm.

Prevertebral Soft Tissue Thickness. Measured at C2 as the narrowest distance between the posterior wall of the trachea and the anterior margin of the C2 vertebral body. Normal <6 mm.

Craniocervical Junction Ligament Anatomy. (A) Coronal 3D T2W image demonstrating the alar ligaments (yellow arrows) , transverse ligaments (red arrows) , and expected location of the apical ligament (blue line) . (B) Sagittal 3D T2W image demonstrating the apical ligament (blue arrow) , tectorial membrane (yellow arrow) , anterior and posterior atlantooccipital ligaments (red) , anterior and posterior atlantoaxial ligaments (light green arrows) , anterior and posterior longitudinal ligaments (white arrows) , and ligamentum flavum and interspinous ligaments (dark yellow arrow) . Determination of intact versus disrupted status of these ligaments is important for determination of ligamentous injury. (C) Diagram of a posterior view of the CCJ; the posterior elements have been removed and ligaments are demonstrated. In the center of the image lies the cruciate ligament. (D) Diagram of a cross-sectional view of the craniocervical junction (CCJ) demonstrating the ligamentous anatomy. (C and D from Boll DT, Haaga JR: CT and MRI of the whole body , 6th ed, Philadelphia, 2017, Elsevier.)

Powers Ratio. Measured as the distance between the basion and anterior margin of the posterior arch of C1, divided by the distance between the opisthion and the posterior margin of the anterior arch of C1. Normal <1

REFERENCES

  • 1. Singh A.K., Fulton Z., Tiwari R., et. al.: Basion-cartilaginous dens interval: an imaging parameter for craniovertebral junction assessment in children. AJNR Am J Neuroradiol 2017 Dec; 38: pp. 2380-2384.
  • 2. Booth T.N.: Cervical spine evaluation in pediatric trauma. AJR Am J Roentgenol 2012 May; 198: pp. W417-W4125.

NORMAL CRANIOCERVICAL JUNCTION LIGAMENTS

Fig. 19.1, Craniocervical Junction Ligamentous Injury. (A) Sagittal T1W and (B) sagittal T2W images demonstrate disruption of the tectorial membrane (white arrow) , apical ligament and anterior atlantooccipital ligament (yellow arrows) , and retroclival hematoma (black arrow) .

TABLE 19.1
Normal Measurements of the Cervical Spine on CT
Measurement Value
Basion-dens interval <10 mm
Anterior atlantodental interval <2.5 mm
Atlantooccipital interval <2.5 mm
Powers ratio <1
Atlantoaxial interval <3.9 mm
Prevertebral soft tissue at C2 <6 mm

CRANIOCERVICAL JUNCTION LIGAMENTOUS INJURY

Key Points

Background

  • Severe trauma resulting in ligamentous injury, instability, and potential spinal cord trauma

    Fig. 19.2, Craniocervical Junction Ligamentous Injury. (A and B) Sagittal reformat CT images demonstrate abnormal basion-dens interval measuring 15 mm, widened condylar gap measuring 10 mm, prevertebral soft tissue swelling (white arrow) , and retroclival soft tissue swelling (black arrow) .

    Fig. 19.3, Craniocervical Junction Ligamentous Injury. (A and B) Coronal T2W images demonstrate disruption of bilateral alar ligaments (white arrows) and a widened left condylar gap (yellow arrow) .

  • Usually associated with significant intracranial traumatic injury

Imaging

  • CT findings include basion dens interval >10 mm, prevertebral swelling, retroclival hematoma, widened atlantooccipital interval >2.5 mm, and widened anterior atlantodental interval >2.5 mm.

    Fig. 19.4, Craniocervical Junction Ligamentous Injury. (A) sagittal reformat CT, (B) sagittal STIR, and (C) coronal 3D T2W images demonstrate prevertebral swelling, basion-dens interval greater than 10 mm, widened C1–C2 interspinous space, ligamentous injury of the anterior atlantooccipital ligament (yellow arrow) , apical ligament (white arrow) , tectorial membrane (black arrow) , posterior atlantoaxial ligament (red arrow) , and right alar ligament (green arrow) .

    Fig. 19.5, Craniocervical Junction Ligamentous Injury. (A and B) Sagittal reformat CT images and (C) sagittal STIR image demonstrate prevertebral edema and ligamentous injury of the anterior longitudinal ligament, anterior atlantooccipital ligament (white arrow) , and posterior atlantoaxial ligament (yellow arrow) .

  • MRI necessary to visualize the disrupted ligaments, including the transverse and alar ligaments, tectorial membrane, and anterior and posterior atlanto-occiptal and atlantoaxial ligaments.

  • Important to perform high-resolution 3D T2W imaging to improve diagnostic accuracy.

    Fig. 19.8, C2 Synchondrosis Fracture. (A) Sagittal reformat CT and (B) sagittal T2W images demonstrate abnormal anterior tilt of the odontoid, abnormal edema along the C2 synchondrosis (white arrow) , prevertebral edema, and widening of the C1–C2 interspinous space from ligamentous injury of the posterior atlantoaxial ligament (yellow arrow) .

  • MRI may also reveal retroclival and prevertebral hematomas, as well as compression and/or injury to the lower brainstem or upper cervical spinal cord.

    Fig. 19.6, Craniocervical Junction Ligamentous Injury. (A) Sagittal reformat CT and (B) sagittal T2W images demonstrate abnormal basion dens interval greater than 10 mm, widened C1–C2 and C3–C4 interspinous spaces, ligamentous injury of the posterior atlantoaxial ligament (white arrow) , tectorial membrane (black arrow) , probable apical ligament disruption, interspinous ligaments of C2–3, C3–4, and C4–5, and trabecular microfractures of thoracic vertebrae (yellow arrows) .

    Fig. 19.7, Craniocervical Junction Ligamentous Injury. (A and B) Sagittal and coronal reformat CT and (C and D) sagittal T2W images demonstrate prevertebral edema, spinal cord injury with hemorrhage (green arrow) , ligamentous injury of the anterior atlantooccipital ligament, anterior and posterior atlantoaxial ligaments (yellow arrows) , apical ligament (orange arrow) , left alar ligament (not shown except for small avulsion fragment on coronal CT), widened facet joints indicative of facet capsular ligament tears at occipital–C1 and C1–C2, C5–6, anterior and posterior longitudinal ligament tear (white arrows) , widened interspinous space due to interspinous ligament and ligamentum flavum tears at C5–6 (red arrow) , and intervertebral disc transection and endplate avulsions at C5–6 (black arrow) .

REFERENCES

  • 1. Lustrin E.S., Karakas S.P., Ortiz A.O., et. al.: Pediatric cervical spine: normal anatomy, variants, and trauma. Radiographics 2003 May–Jun; 23: pp. 539-560.
  • 2. Meoded A., Singhi S., Poretti A., et. al.: Tectorial membrane injury: frequently overlooked in pediatric traumatic head injury. AJNR Am J Neuroradiol 2011 Nov–Dec; 32: pp. 1806-1811.

C2 SYNCHONDROSIS FRACTURE

Key Points

Background

  • Hyperflexion mechanism

    Fig. 19.9, Facet Dislocation. (A and B) Sagittal reformat CT and (C) sagittal T2W images demonstrate malalignment with C4–C5 anterolisthesis, narrowed C4–C5 disc space, prevertebral edema, ligamentous injury of the anterior and posterior longitudinal ligaments, C3–C4 and C4–C5 interspinous ligaments, disc herniation, spinal cord compression, and cord edema.

  • Spinal injury finding found in younger patients because the cartilage between the odontoid and body of C2 does not ossify until age 5 to 7 years.

Imaging

  • Results in angulation of the dens with respect to the C2 body

  • May have associated prevertebral soft tissue swelling, widened C1–C2 interspinous space, disruption of spinolaminar line, ligamentous injury of anterior longitudinal ligament (ALL), and posterior atlantoaxial ligament (PLL)

REFERENCE

  • 1. Rusin J.A., Ruess L., Daulton R.S.: New C2 synchondrosal fracture classification system. Pediatr Radiol 2015 Jun; 45: pp. 872-881.

FACET DISLOCATION

Key Points

Background

  • Severe traumatic injury resulting in dislocation of the facets, ligamentous injury and usually spinal cord injury

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