====== Cervical Spine Radiography in Pediatric cervical spine injury ======

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[[Cervical Spine Radiography]] in [[Pediatric cervical spine injury]] can be very challenging due to the wide range of normal anatomic variants and synchondroses, combined with various injuries and biomechanical forces that are unique to children. 

Features such as hypermobility between C2 and C3, the pseudo spread of the atlas on the axis, pseudo subluxation, the absence of lordosis, anterior wedging of vertebral bodies, pseudo widening of prevertebral soft tissue, and incomplete ossification of synchondrosis can be mistaken for traumatic injuries. The interpretation of a plain radiograph of the pediatric cervical spine following trauma must take into account the age of the child, the location of the injury, and the mechanism of trauma. Comprehensive knowledge of the specific anatomy and biomechanics of the childhood spine is essential for the diagnosis of suspected cervical spine injury. With it, the physician can, on one hand, differentiate normal physes or synchondroses from pathological fractures or ligamentous disruptions and, on the other, identify any possible congenital anomalies that may also be mistaken for an injury
((Adib O, Berthier E, Loisel D, Aubé C. Pediatric cervical spine in emergency:
radiographic features of normal anatomy, variants and pitfalls. Skeletal Radiol. 
2016 Dec;45(12):1607-1617. Review. PubMed PMID: 27650073.
)).

Although a child can be defined radiographically as an individual with open epiphyses, this definition is not applicable in the cervical spine. By the time a child is 8–10 years old, the cervical spine reaches adult proportions
((Bailey DK. The normal cervical spine in infants and children. Radiology 1952; 59:712-719.))
((Baker C, Kadish H, Schunk JE. Evaluation of pediatric cervical spine injuries. Am J Emerg Med 1999; 17)).

After the age of 10–12 years, the clinical sequelae of pediatric and adult trauma are similar 
((Hall DE, Boydston W. Pediatric neck injuries. Pediatr Rev. 1999
Jan;20(1):13-9; quiz 20. Review. PubMed PMID: 9919047.
)).

===== Lateral view =====
 

Optimizing the diagnostic accuracy of the lateral view requires attention to detail; the [[external auditory canal]]s and the lower cervical facets should be superimposed. Careful evaluation of the intraspinous distances, disk spaces, and neuroforamina is necessary at each level. The anterior and posterior cervical and spinolaminar lines should be assessed for subtle ligamentous disruption, recognizing that pseudosubluxation, which is a normal variant, can cause apparent disruption of the anterior and posterior cervical lines. Pseudosubluxation is seen as anterior subluxation of C2 on C3, which can occur at a progressively lower level in the older child. The amount of subluxation is typically less than 2 mm. The spinolaminar line should not be disrupted, and the C2 line, which is a line drawn tangential to the posterior margin of C2, should contact, not intersect, the upper corner of C3
((Swischuk LE. Anterior displacement of C2 in children: physiologic or pathologic? Radiology 1977; 122:759–763))
((Shaw M, Burnett H, Wilson A, Chan O. Pseudosubluxation of C2 on C3 in polytraumatized children: prevalence and significance. Clin Radiol 1999; 54:377–380)).

The younger the child, the more likely the upper cervical spine or craniovertebral junction will be affected; distraction and ligamentous injuries are more common than bony injury. Subtle, but significant, injury to the subchondral synchondrosis may escape diagnosis. Although dorsal tilting of the dens is normal, ventral tilting is not.

The Wackenheim line is defined as a line along the posterior cortical margin of the clivus, which should normally intersect the posterior one third of the dens.
The Powers ratio is calculated by dividing the distance between the basion and posterior arch of C1 by the distance between the opisthion and anterior arch of C1. A line along the posterior dens and the perpendicular measurement from that line to the basion determines the basion axial interval
((Booth TN. Cervical spine evaluation in pediatric trauma. AJR Am J Roentgenol. 
2012 May;198(5):W417-25. doi: 10.2214/AJR.11.8150. Review. PubMed PMID: 22528922.
)).

The basion dens interval, measured from the basion to tip of the dens, is the most easily obtained measurement on conventional radiographs.

Significant ligamentous injury can occur without marked prevertebral soft-tissue swelling. Hypertrophied retropharyngeal lymphoid tissue in young children should measure less than one half of the vertebral body at the C2–C3 level 
((Egloff AM, Kadom N, Vezina G, Bulas D. Pediatric cervical spine trauma imaging: a practical approach. Pediatr Radiol 2009; 39:447–456))
((Lustrin ES, Karakas SP, Ortiz AO, et al. Pediatric cervical spine: normal anatomy, variants and trauma. RadioGraphics 2003; 23:539–560))
((Smoker WR, Khanna G. Imaging the craniocervical junction. Childs Nerv Syst 2008; 24:1123–1145)).

===== Oblique radiograph =====


Oblique radiographs add little to increase the sensitivity of conventional radiographs in the pediatric population
((Ralston ME, Ecklund K, Emans JB, Torrey SB, Bailey C, Schutzman SA. Role of oblique radiographs in blunt pediatric cervical spine injury.Pediatr Emerg Care 2003; 19:68–72)).

===== Flexion-extension radiography =====

FE radiography following the initial MRI did not have a significant effect on reducing time to cervical collar removal or overall hospital length of stay. In addition, in 3 of 6 cases (50.0%) in which surgical fixation was required, MRI detected ligamentous and/or bony injury while FE radiography was normal
((Zhang JF, Umenta J, Ali A, Reynolds R, Ham PB, Thomas RD, Piryani R, Izhar M, Wrotniak B, Swayampakula AK. Cervical spine flexion-extension radiography versus magnetic resonance imaging in pediatric patients following blunt traumatic injury. Trauma Surg Acute Care Open. 2023 Feb 6;8(1):e001016. doi: 10.1136/tsaco-2022-001016. PMID: 36761391; PMCID: PMC9906377.))

Flexion-extension radiography is not indicated in the setting of an acutely traumatized young child. The dynamic evaluation of cervical stability is best performed with an active range of motion, and the traumatized child suspected of having CSI should not be subjected to passive flexion and extension in the acute setting. The examination is usually limited by the presence of muscle spasm and pain and places the patient at risk for spinal cord injury in the setting of an unstable spine, resulting in appropriate avoidance by many pediatric radiologists and trauma physicians of passively manipulating the cervical spine of an acutely injured child.
Ralston et al. 
((Ralston ME, Chung K, Barnes PD, Emans JB, Schutzman SA. Role of flexion-extension radiographs in blunt pediatric cervical spine injury. Acad Emerg Med 2001; 8:237–245))
and Dwek et al. 
((Dwek JR, Chung CB. Radiography of cervical spine injury in children: are flexion-extension radiographs useful for acute trauma? AJR 2000; 174:1617–1619))
found that flexion-extension radiographs offer no additional information when anteroposterior and lateral radiographs are normal or show straightening of the normal cervical lordosis. However, flexion-extension images are useful in the follow-up evaluation of the child previously found to have ligamentous injury associated with instability.