Key points

Introduction

Diagnosis and management of subaxial cervical spine injuries in pediatric patients have received less attention in the published literature compared with injuries in adults. Differences in anatomy, biomechanics, fracture patterns, and management options must be taken into account and treatment must be individualized to each patient.

Introduction

Diagnosis and management of subaxial cervical spine injuries in pediatric patients have received less attention in the published literature compared with injuries in adults. Differences in anatomy, biomechanics, fracture patterns, and management options must be taken into account and treatment must be individualized to each patient.

Anatomy and biomechanics

The subaxial cervical spine includes vertebral levels C3 through C7. The first 2 levels represent a typical cervical vertebral level. C7 retains the general structure of the other cervical levels but the absolute size of this level more resembles the thoracic spine. A typical cervical vertebra includes a small body connected by short pedicles to the lamina. Spinous processes are diminutive and often bifid. The spinous process of C7 is typically large and uncommonly bifid. Transverse processes of C3-6 are small and are made smaller by the presence of the foramen transversarium. The transverse process of C7 is, conversely, larger with a smaller foramen transversarium that may also be absent.

Three anatomic differences between the pediatric and adult cervical spine are critical when considering a patient with a possible cervical spine injury. First, the articular processes in the cervical spine of pediatric patients retain a more axial orientation, reducing resistance to translation. Second, the vertebral bodies are more wedged anteriorly. Both allow for an increased amount of normal anatomic movement of the vertebral bodies of the subaxial cervical spine in children, especially those under 8 years old. In general, at C2-3 and C3-4, up to 4.5 mm of translation of the superior vertebral body relative to the inferior vertebral body in the sagittal plane may be considered normal, termed pseudosubluxation . Third, the size of the head of a child relative to the remainder of the body is proportionately larger, increasing the load borne by the cervical spine when undergoing rapids movements, such as whiplash. The fulcrum of movement in flexion injuries shifts progressively lower with increased age: C2-3 for infants and young children, C3-4 for children aged 5 to 6, and C5-6 for adolescents, similar to mature adults.

The pediatric cervical spine is significantly more elastic than the adult spine, leading to different injury patterns. The anterior longitudinal ligament (ALL) and posterior longitudinal ligament (PLL) traverse the entirety of the spine from the sacrum up and run along the anterior and posterior faces of the vertebral bodies. The ALL attaches to the anterior tubercle of C1 (also known as the atlas) superiorly. The PLL fuses with the tectorial membrane. These 2 ligaments provide the most significant stability to the subaxial cervical spine. Other ligamentous structures with a more minor contribution include capsular ligaments surrounding the facet joints and the interspinous ligaments between spinous processes. It is important to recognize that in children, these structures are inherently more lax, allowing for greater movement of the spine than in adults.

The uncovertebral joint is a joint unique to the cervical spine. Its relationship to both neural and vascular structures makes it an important anatomic landmark. The uncinate process, a bony ridge projecting superiorly from the posterior and lateral aspect of each cervical vertebral body, may be absent in young children. It articulates with the inferior aspect of the vertebral body above and is encapsulated by ligamentous tissue that extends from the PLL. This ligamentous tissue also encases the nerve roots, which lie posterior to the uncovertebral joints, and the vertebral artery, which lies laterally. It is not until the age of 8 years that the joints develop to their full extent. As a consequence, the normal resistance to rotation provided by this joint in the adult cervical spine is minimal in children under the age of 8 years.

Finally, the foramen transversarium represents a unique bony structure within the cervical spine. It provides protection for the vertebral artery as it traverses the neck while also leaving it vulnerable to injury in cases of cervical spine trauma. As discussed previously, it is typically smaller in C7 than the remainder of the cervical spine. Although the vertebral artery most commonly enters at C6, it has been found to enter at C5 (5%), C4 (1%), C7 (0.8%), and C3 (0.2%).

Epidemiology and injury patterns

Since 2005, nationwide prevalence of traumatic pediatric cervical spine injury was 2.07%, with a mortality rate of 4.87%. Motor vehicle accidents are the most common cause of pediatric cervical spine injuries (57.51%), followed by falls, sports, diving accidents, firearms, and child abuse. Upper cervical spine injury (C1-4), cervical fracture with spinal cord injury, spinal cord injury without radiographic abnormality (SCIWORA), and dislocation vary inversely with age. Obstetric complications are the primary cause of cervical spine injury in newborns, can be difficult to diagnose, and should be suspected in infants with apnea and flaccid quadriplegia after traumatic delivery. The characteristics of the cervical spine in a pediatric patient change significantly with age, with mature development not present until 8 years of age. The immaturity of the young pediatric cervical spine, including weaker ligaments and neck muscles, a relatively large head, horizontally oriented facets, and incomplete ossification expose children under the age of approximately 8 years old to an increased risk of cervical spine injury. Pure ligamentous injuries and SCIWORA are more common in children under the age of 9 whereas isolated bony injury and fracture subluxation injuries are more common in the more developed spine of older children.

Relative to other parts of the spine and spinal cord, the cervical spine and spinal cord are the most susceptible to traumatic injury in children. Three-quarters of SCIWORA and fracture subluxations with all purely ligamentous injuries in children occurred in the cervical spine.

Clinical and radiographic evaluation

The evaluation of children who have suffered traumatic injury, especially after blunt trauma and high-energy mechanisms, like motor vehicle accidents, can be challenging. Presenting symptoms in awake patients may include neck pain, rigidity, torticollis, numbness, radicular pain, or weakness. Unconscious patients are more difficult to evaluate and should be maintained in cervical orthosis until definitive imaging and/or examination rules out injury. Younger patients with larger heads relative to their body should have appropriate torso elevation (mean 25 mm) to preserve neutral position and avoid unintentional flexion and exacerbation of kyphotic deformity while being transported by backboard.

Given the differences in shape, biomechanics, and flexibility of the pediatric cervical spine (described previously), diagnosis of cervical spine injury can be challenging. Children who have suffered significant trauma who do not meet National Emergency X-Radiography Utilization Study (NEXUS) standard criteria should undergo at least anterior/posterior and lateral cervical spine radiography. In cases of ground level falls, CT imaging is generally overused, with less than 1% detection of cervical spine fractures, all identified by NEXUS and Canadian Cervical Spine Rule for radiography criteria with 100% sensitivity. Adoption of standardized protocols based on NEXUS criteria has been shown to significantly reduce costs and unnecessary radiation exposure in children evaluated for cervical injury. Studies in adults have demonstrated the significantly higher sensitivity of CT imaging for the detection of cervical spine injuries compared with plain films, especially in intubated and head-injured patients. In the pediatric population, CT imaging has been recommended in cases of inadequate visualization, suspicious findings, or evidence of fracture/displacement on plain films and in obtunded children with a high-energy mechanism and blunt trauma.

MRI is superior to CT in delineation of soft tissue injury and is useful in cases of neurologic deficit to evaluate for disk herniation, spinal cord contusion, nerve root compression, and epidural/subdural hematoma. Despite improved soft tissue visualization, several recent studies have called into question the utility of MRI over modern-era fine-cut CT for the diagnosis of clinically relevant ligamentous instability and spinal instability in patients with head injury, although this remains controversial. Recent evaluation of the diagnostic performance of the Subaxial Cervical Spine Injury Classification (SLIC) showed improved interobserver agreement when using CT alone and limited added value for MRI in determining conservative versus surgical management. Flexion extension films in awake, cooperative patients have traditionally been used for diagnosis of delayed, dynamic instability, although several studies have questioned their utility for detecting instability in the absence of abnormalities on fine-cut CT imaging.

Multiple classification systems have been proposed to serve as a guide to rational treatment decision making in adults, although none has been widely accepted by the world community and none has been objectively validated in pediatric populations. The Cervical Spine Injury Severity Score System (CSISS) has been demonstrated to be a reliable, comprehensive scoring system to describe subaxial cervical spine injuries, with intraobserver and interobserver intraclass correlation coefficients of 0.977 and 0.883, respectively. The CSISS uses a traditional morphologic description of fractures, which is familiar to spinal neurosurgeons ( Box 1 ), combined with a 4-column model to help estimate stability based on a 20-point scale. The original SLIC included morphologic, ligamentous, and neurologic examination information in its point scale ( Table 1 ) and has been shown to have excellent intraobserver and interobserver reliability. The Spine Trauma Study Group published treatment recommendations based on this scale, with a score of 3 or less suggesting nonsurgical treatment and a score of 5 or more suggesting surgical treatment, with 4 being indeterminate. The few external validation studies that have been performed of the SLIC as a treatment algorithm have shown variable interobserver agreement on both classification and treatment choice, with some questioning its clinical utility. A new version of the SLIC that is more similar to that used for thoracolumbar fractures, the AOspine SLIC, has been recently proposed and initial experience suggests moderate to substantial reliability among spine surgeons. Despite these limitations, an accepted system, once validated in pediatric patients, could ultimately provide a useful framework to improve communication of injury patterns, determine prognosis, and suggest appropriate treatment, while standardizing reporting of injuries for analysis in future outcome studies.

In the absence of any universally accepted classification system, the radiographic findings most commonly associated with cervical instability that are generally accepted in the pediatric literature include burst fracture, widening or subluxation of facet joints, significant separation of the spinous processes, vertebral body subluxation greater than 4.5 mm at C2-3 or C3-4 (<8 years old) or greater than 3.5 mm at any level in children greater than 8 years old, angulation of the vertebral body greater than 7, teardrop injury with disk disruption, and fracture dislocation ( Box 2 ).

Box 2

• 
  

  Vertebral subluxation greater than 4.5 mm at C2-3 or C3-4 (<8 years old) or greater than 3.5 mm at any level (>8 years old)

  
  
• 
  

  Angular displacement >7 degrees

  
  
• 
  

  Tear drop injury with disk disruption

  
  
• 
  

  Unilateral/bilateral facet subluxation

  
  
• 
  

  Burst fracture

  
  
• 
  

  Fracture dislocation

  
  
• 
  

  Isolated ligamentous injury with significant facet or interspinous widening

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

Update on New Imaging Techniques for Trauma Thoracolumbar Trauma Classification Classification and Management of Pediatric Craniocervical Injuries Pediatric Thoracolumbar Spine Trauma Treatment of Odontoid Fractures in the Aging Population Complications in the Management of Patients with Spine Trauma

Stay updated, free articles. Join our Telegram channel

Join