Pediatric C-spine Clearance: Can we use NEXUS?

Let’s face it. As emergency physicians, clearing the C-spine on an injured adult seems like a daily practice. We have evidenced based rules that we can use as guidelines and often if there is any doubt about injury or if the patient is obtunded/unable to accurately give a history, a one time dose of radiation is not really a huge problem. Pediatric C-spines are an entirely different story. Nothing is more frightening than seeing the crying 2 year old boarded and collared after an accident and wondering if there is any way to clear his C-spine without exposing him to unnecessary radiation. And to top it all off, he’s most likely frightened and crying and not really able to explain to you what he is feeling. Here we will talk about some of the current practices with clearing the pediatric C-spine as well as the evidence (or lack thereof) behind this frightening subject.

The table below reports the normal measurement for pediatric C-spines

Parameter	Normal Value
C-1 facet-occipital condyle distance	≤ 5 mm
Atlanto-dens interval	≤ 4 mm
Pseudosubluxation of C2 on C3	≤ 4 mm
Pseudosubluxation of C3 on C4	≤ 3 mm
Retropharyngeal space	≤ 8 mm (at C-2)
Retrotracheal space	≤ 14 mm (at C-6, under age 15 yr.)
Tong ratio (canal to vertebral body)	≥ 0.8
Space available for cord	≥ 14 mm

The pediatric C-spine does not become like the adult until about the age of 8 years. Considering the large difference in ratio of head size to body, the infant will experience different inertial forces compared to fully matured individuals. Ligaments and joint capsules are more lax, facets are more horizontal, and the vertebral bodies are wedge shaped. All of these factors increase the risk of injury to the levels of C1 and C2. Cervical spine injuries occur mainly in the upper cervical spine above C4 in patients 8 years of age or younger which most often involve the occiput, C1, and C2 complex and thus carries increased risk of fatality. Patients older than 8 years of age typically sustain more injuries below C4 and carry a much lower fatality rate. Up to 30% of traumatic spine injuries in children present as a traumatic myelopathy known as spinal cord injury without radiographic abnormality (SCIWORA).

Unique Anatomic Features of Children Age 8 and Younger

Large head-to-body ratio
Ligamentous laxity
Relative paraspinal muscle weakness
Horizontal, shallow facet joints
Increased spinal column elasticity
Forces dissipated over several adjacent segments
SCIWORA possible
Presence of the ring apophysis
Fractures traverse vertebral body growth plate.

Obviously no exam is complete without a history and physical, so after that’s all done the next thing is, “who needs imaging”?

Is there any pediatric evidence?

l 1 prospective study

l Peds subset of NEXUS – Viccellio et al

l Canadian C-spine Rule

NEXUS and Viccellio- The objective of this study was to examine the incidence and spectrum of spine injury in patients who are younger than 18 years and to evaluate the efficacy of the National Emergency X-Radiography Utilization Study (NEXUS) decision instrument for obtaining cervical spine radiography in pediatric trauma victims. Subset of 34.000 patients in the NEXUS study that evaluated the 3065 patients (9.0% of all NEXUS patients) who were younger than 18 years in this cohort, 30 of whom (0.98%) sustained a C-Spine injury. Included in the study were 88 children who were younger than 2, 817 who were between 2 and 8, and 2160 who were 8 to 17. Fractures of the lower cervical vertebrae (C5-C7) accounted for 45.9% of pediatric CSIs. No case of spinal cord injury without radiographic abnormality (SCIWORA) was reported in any child in this study, although 22 cases were reported in adults. Only 4 of the 30 injured children were younger than 9 years, and none was younger than 2 years. Tenderness and distracting injury were the 2 most common abnormalities noted in patients with and without CSI. The decision rule correctly identified all pediatric CSI victims (sensitivity: 100.0%; 95% confidence interval: 87.8%-100.0%) and correctly designated 603 patients as low risk for CSI (negative predictive value: 100.0%; 95% confidence interval: 99.4%-100.0%).

Bottom line:

l Authors “cautiously endorse” the use of the NEXUS criteria in children over age 8

l Not enough power to ensure that the tool is safe to use in younger children

l However, authors state that there is not a single case in the medical literature of a child with a c-spine injury who would have been classified as low risk using NEXUS

Canadian C-spine Rule- Has not been evaluated for use in patients < 16 years.

Are there any consensus statements or guidelines?

l American Association of Neurosurgeons (Guidelines committee of the section on disorders of the spine) [AANS]

Management of Pediatric Cervical Spine and Spinal Cord Injuries

Neurosurgery 2002;50(3) March supp

l Guidelines based on available evidence and expert opinion and they state that we can use Nexus in children >8 years of age.

l Although evidence is lacking for those <8, expert opinion supports the use of the NEXUS criteria and given lack of evidence, and possible communication barriers in young children, it would be reasonable to consider imaging in high risk mechanisms:

high speed MVC
fall > 8 ft or significant height for age
axial load injury

What about infants?

l See them quickly

l Assess for altered LOC, neuro deficit, distracting injury

l If no injury apparent, remove immobilization equipment in protected environment

l Observe for spontaneous movement of neck

l Most small children will “clinically clear” themselves

Imaging

1) General agreement that a lateral and AP c-spine film are necessary. C-spine XRays can be used in children as they are often better quality than in adults and the sensitivity of the lateral film alone in peds is comparable to the adult literature ~85%

2) What about the odontoid view? In older children, this view must be added, but in the younger patient where this is difficult to obtain, what do we do? Let’s consider this:

0-3 years: 50% of injuries are at C1 / C2 level
4-12 years: 8% of injuries are at C1 / C2 level
Buhs et al (2000) J Ped Surg – Retrospective review of all c-spine injuries in children< 16 yrs over 10 year period at 4Detroit trauma centres
Bottom line: AP/Lat are not enough if the suspicion is high and you need to get a good look at C1/C2. The only answer may be to get a CT of C1-2.

3) Other studies looked at oblique and flex-ex views. Basically, if the AP/Lat are normal, oblique and flex-ex films are unlikely to add additional information.

4) CT is valuable for viewing regions not visualized on plain film ie – skullbase to C3 in intubated patient

Remember: a large proportion of young children with c-spine injury will have an isolated ligamentous injury, a normal CT cannot be used to exclude a c-spine injury.

5) What about MRI? What should I do for the child that has a normal set of XRays as well as a normal CT but still has some appreciable neurologic deficit and persistent neck pain

They may still have a significant injury, so discuss case with referring neurosurgeon
Those with neuro deficits likely need urgent MRIà a) Flynn et al (2002) J Peds Ortho b) Keiper et al (1998) Neurorad
Those with ++ pain may benefit from one or more ofAspencollar, outpatient MRI, and neurosurgery follow-up.