Clearing the Pediatric C-Spine Kelly R. Millar, MD, FRCPC Emergency Physician, Alberta Children’s Hospital Assistant Professor, University of Calgary

Overview Epidemiology Anatomic considerations Clearing the pediatric c-spine Who needs imaging? What films should be ordered? Who needs a CT/MRI? Interpretation of Pediatric c-spine films Cases

Epidemiology of Pediatric Cervical Spine Injury 5% of all spinal cord injuries occur in children 1000 pediatric spinal cord injuries in the US each year 80% of spinal injuries in children < 8 yrs are cervical (vs 30-40% in adults)

Epidemiology Many small case series Often include up to age 20, so data very skewed to older “children” 2 recent large pediatric data sources have fair number of younger children: The largest prospective series is the pediatric subset of the NEXUS trial The largest retrospective series comes from the National Pediatric Trauma Registry

How common are pediatric C-spine injuries?

National Pediatric Trauma Registry Prospective, multi-center database Includes ages 0-20 Primary diagnosis traumatic injury Patel et al (2001) J Ped Surg 10 yr review (1988-98) > 75,000 pediatric injuries in database 1.5% had cervical spine injury (N = 1098)

National Pediatric Trauma Registry Kokoska et al (2001) J Ped Surg 6 year review of same database 1994 – 99 Age distribution of c-spine injuries → Younger age groups well represented Age (yrs)

Do children have the same injury patterns as adults? NO! Injuries differ in location and type Why? Developing spine has unique anatomy

Anatomic Considerations Large head Torque and acceleration stress occur higher in the c-spine Fulcrum of motion C2-C3 in young children (vs C5-C6 in adults) Younger children have an increased incidence of high C-spine injury

Location of Injury National Pediatric Trauma Registry Patel et al (2001) J Ped Surg Age Age 1- 10 yrs Age > 10 yrs C1 – C4 injury 85% 57% Kokoska et al (2001) J Ped Surg

anterior wedging of vertebral bodies horizontal alignment of facet joints Children prone to anterior dislocation Young Child Mature University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Underdeveloped neck musculature Ligamentous laxity Younger children have an increased incidence of ligamentous injury

Believed that the laxity of the peds spine acts to protect against spinal fracture in low energy trauma, however, may lead to SCIWORA in high-energy trauma More on SCIWORA in a moment…

Type of injury Age 1- 10 yrs Age > 10 yrs Fractures 42% 65% Dislocations 31% 20% SCIWORA 27% 15% National Pediatric Trauma Registry: Kokoska et al (2001) J Ped Surg

How common are neuro deficits? National Pediatric Trauma Registry: Patel et al (2001) J Ped Surg

What is SCIWORA? Def: Spinal cord injury without radiographic abnormality on plain film or CT Mechanism: transient vertebral displacement with subsequent realignment resulting in damaged spinal cord and normal appearing vertebral column Young spinal column can stretch up to 5cm Spinal cord ruptures after 5mm of traction

SCIWORA How common is it? Literature extremely inconsistent with definition and incidence Reported as 0-50% of peds spinal cord injuries National Pediatric Trauma Registry: 17% NEXUS: none!!

SCIWORA – case series Common themes: Up to half may have delayed onset of symptoms (usually within 48 hrs) SCI can be severe Chance of recovery low if complete May be related to spinal cord infarction

Epidemiology: Bottom Line C-spine injuries in children are rare, but they do occur in about 1.5% of blunt trauma patients In young children, be on look out for: High c-spine injury Ligamentous injury

How can we protect the pediatric C-spine?

Begins in Prehospital Setting: Immobilization Aim for “neutral position” Big head When laying flat on backboard, neck is flexed Must accommodate large occiput, using either an occipital depression or padding under the torso

Immobilization Best immobilization achieved by modified spine board, rigid collar and taping Too large a collar can distract the neck and worsen an injury – blocks are preferable to a poorly fitting collar

OK… Now the collar’s on… How do I get it off? Challenges: Preverbal or crying children: Difficult to assess tenderness Difficult to perform detailed neurologic exam Questions: Who needs imaging? What type of imaging is needed? When do I need a CT or MRI?

Clearing the Pediatric C-Spine PART 1: Who needs imaging? Is there any pediatric evidence? 1 prospective study Peds subset of NEXUS – Viccellio et al 1 retrospective study Isolated head injuries – Laham et al

Imaging – Peds subset of NEXUS Viccellio et al (2001) Pediatrics Prospective study of patients with blunt trauma + cervical spine radiography Used 5 low-risk criteria: No midline cervical tenderness No evidence of intoxication No altered level of consciousness No focal neurological deficit No painful distracting injury If all 5 criteria met – considered low risk

NEXUS – peds subset 3065 patients < 18 years (9% of NEXUS) Total # c-spine injuries: 30 603 / 3065 considered “low risk” (20%) All low risk patients had negative radiographic evaluations (100% sensitive)

NEXUS – peds subset Problem: Numbers are small, so 95% CI for sensitivity: 87.8% - 100% Problem: Very few injuries in younger kids Grouped as follows: 0-2 (lack of verbal skills) N = 88 (0) 3-8 (immature cervical spine) N = 817 (4) 9-17 (older children) N = 2150 (26)

NEXUS – peds subset Bottom line: Authors “cautiously endorse” the use of the NEXUS criteria in children over age 8 Not enough power to ensure that the tool is safe to use in younger children 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

Laham et al (1994) Ped Neurosurg Retrospective review of 268 children with apparent isolated HI 2 high risk criteria = incapable of verbal communication (due to age or HI) and neck pain Did x-rays in all kids No abnormal x-rays in low risk group 7.5% abnormal in high risk group Authors concluded: In isolated HI with no neuro deficits, no x-rays needed if child can communicate and has no neck pain

What about the Canadian C-Spine Rules? Have not been evaluated for use in patients < 16 years

Are there any consensus statements or guidelines? 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 Guidelines based on available evidence and expert opinion

AANS Bottom Line: Children > 8 years Evidence supports the use of NEXUS criteria: Image if any one of: Midline tenderness Focal neurological deficit Altered level of consciousness Evidence of intoxication Painful distracting injury

AANS Bottom Line: Children 8 years and under who are conversant Although evidence is lacking, expert opinion supports the use of the NEXUS criteria 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 axial load injury

What should we do with infants? NEXUS – 88 patients < 2 yo – no injuries NPTR – children < 2 yo : ~ 8 injuries per yr No studies with large enough numbers to generate evidence-based practice recommendations Have to go to expert opinion

AANS Bottom Line: Non-conversant Children Advise obtaining images in all non-conversant children who have “experienced trauma” Practically, this is not what’s done in most Canadian pediatric EDs

What should we do with infants? See them quickly Assess for altered LOC, neuro deficit, distracting injury If no injury apparent, remove immobilization equipment in protected environment Observe for spontaneous movement of neck Most small children will “clinically clear” themselves

Clearing the Pediatric C-Spine PART 2: What films do I need?

General agreement that a lateral and AP c-spine film are necessary The sensitivity of the lateral film alone in peds is comparable to the adult literature ~85%

Odontoid views? Many authors have questioned the need Swischuk surveyed 984 pediatric radiologists (432 responses) Obtained reports of 46 pediatric fractures that were missed on lateral view and seen on odontoid view Calculated a miss rate of 0.007 per year per radiologist

Odontoid views? Buhs et al (2000) J Ped Surg - Retrospective review of all c-spine injuries in children< 16 yrs over 10 year period at 4 Detroit trauma centres AGE N Occ/C1/2 Lat/AP Missed occip – C2 0-8 15 6 (40%) 13 (87%) 2 – both odont # - plain odont unobtainable (seen on CT or MRI) 9-16 36 9 (25%) 23 (65%) 2 – both odont # - 1 seen on odont / 1 on CT can’t r/o fracture with AP/lat alone

But odontoid views are hard to get in young children!!! Consider: 0-3 years: 50% of injuries are at C1 / C2 level 4-12 years: 8% of injuries are at C1 / C2 level Bottom line: If you are worried enough to image the c-spine, you need to get a good look at C1 / C2 ~need odontoid view or CT

Oblique views? Ralston et al (2003) Ped Emerg Care: Blinded retrospective review (8 year period) Blunt trauma patients ≤16 yrs AP/Lat + oblique views N = 109

Oblique views? All with normal AP/Lat had normal obliques (N = 78) If AP/Lat normal, obliques unlikely to add additional information 4 obliques resulted in revision of impression: 3 from equivocal to normal 1 from equivocal to abnormal (final dx = no injury) May be of assistance in equivocal situation

Flexion-Extension views? Ralston et al (2001) Acad Emerg Med Blinded retrospective review (6 year period) Blunt trauma patients ≤16 yrs AP/Lat (+ odont in 83%) + flex/ex views N = 129 45 patients had initial AP/Lat read as normal – all had normal flex/ex views (no revision of impressions) If primary series is normal…flex/ex views do not add info 84 patients had initial AP/Lat read as abnormal (including loss of lordosis -79 had revision of impression)

Revision of Impressions Impression After Lat/AP Impression After Lat/AP + Flex/ex Final Diagnosis (considering CT, MRI, clinical) Loss of lordosis [N=50] Normal SCIWORA (2) Ligament injury (2) Disc injury (1) Subluxation ? or Segmental kyphosis [N=22] + Subluxation (3) Ligamentous injury (2) Normal (19) Fracture (1) Soft Tissue Swelling [N=5] Normal (5)

Flexion-Extension views? Normal flex-ex views do not rule out an injury If plain films worrisome, more sensitive modalities are warranted (CT +/- MRI) May consider flex-ex after to look for major instability If the concern is significant pain despite normal plain films, quality of flex-ex view likely limited due to pain and they cannot be used to “rule out” an injury

To CT or not to CT…. Routinely used in adults trauma patients to examine c-spine There are significant concerns that exposing children to CT radiation may lead to an increased lifetime risk of cancer Try to be much more selective with the use of CT in children Limit scans to specific areas of interest

Indications for CT Valuable for: Defining anatomy in regions where an abnormality is suspected on plain film 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 CT can miss odontoid #

Evidence for early CT? Keenan et al (2001) AJR Retrospective study of 63 kids Head injury + C-spine plain films 21/63 had early CT c-spine with initial head CT 42/63 had plain films alone - often repeat attempts Analyzed multiple patient factors + total radiation dose received in process of imaging c-spine Found kids in high speed MVC with GCS <8 had same radiation with repeated plain films as with early CT (new generation, helical CT with recons)

How about MRI ??? Keiper et al (1998) Neurorad Retrospective case review Children with hx of blunt c-spine trauma Normal plain films + normal CT One of: Persistent or delayed neuro symptoms Persistent significant neck pain N = 52 MRI abnormal in 16/52 (31%) 4 went on to operative management

MRI ??? Flynn et al (2002) J Peds Ortho

What do these MRI studies mean for me? (…I can’t just order an MRI!) In children with normal plain films and normal CT who have either: Neurologic deficit Significant persistent neck pain ~ they may still have a significant injury, so discuss case with referring neurosurgeon Those with neuro deficits likely need urgent MRI Those with ++ pain may benefit from one or more of Aspen collar, outpatient MRI, and neurosurg follow-up (at discretion of neurosx)

Clearing the Pediatric C-Spine PART 3: Now I know what tests to do… How do I interpret pediatric C-spine films?

Follow same general approach as in adult c-spine films: A – alignment B – bones C – cartilage D – dens S – soft tissues Are some unique features in children that are important to recognize

Alignment – Subluxation of C2/C3? University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Alignment - Pseudosubluxation 24% C2 on C3 14% C3 on C4 (Age <7 years) Swischuk’s line: posterior arch of C1 to C3 – should come within 1 mm of post arch of C2 University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Bones Wedge shaped vertebral bodies Ossification centres Can appear like tear-drop fractures of the vertebral bodies University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Dens Predental space – allow up to 5 mm in young children Subdental synchondrosis - lucency at base of dens Dens fuses with body of C2 between ages 4 - 6 years A thin lucency may be appreciable on the lateral view for many years (50% up to age 11) May have ossification centre at tip of dens University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Prevertebral Soft Tissues Allowable thickness changes with age In general: Above glottis: ½ vertebral body Below glottis: 1 vertebral body Often falsely thickened 2° to neck flexion (big occiput) or expiration University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Radiographically, most of the adult characteristics are present by age 8 Characteristics of peds c-spine injuries trend towards that of adults at about age 8-10 years not equal to adults until about 15 years

Clearing the Pediatric C-Spine PART 4: Specific injuries to watch for

Case 1 5 yo girl Hit by car while riding bike VSA at scene Vitals recovered by EMS Rose et al, Am J Surg 2003;185(4)

Atlanto-Occipital Dislocation 2.5 x more common in children than adults Due to small occipital condyles and horizontal atlanto-occipital joints Suspect if distance between occipital condyles and C1 is > 5mm at any point Usually have ++ soft tissue swelling

Wackenheim Clivus Line Line from clivus should just touch posterior odontoid tip The Encyclopaedia of Medical Imaging www.amershamhealth.com

Case 2 2 yo female High speed MVA Closed HI (GCS 11) Proctor (2002) Crit Care Med

C1 – C2 Subluxation Predental space = 8mm Prevertabral soft tissue swelling > ½ vertebral body

Case 3 3 yo male Fell out of barn loft Alert, crying but consolable Says his head hurts Makes no attempt to voluntarily move neck University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray)

Dens Fracture Suspicious for dens fracture: widening of the synchondrosis anterior tilting of the odontoid (may be posteriorly tilted in normal children)

Dens Fracture Often lack neuro symptoms as spinal canal is wide at that level Most common symptoms: Occipital pain (injury to greater occipital nerve) Refusal to extend neck Believed to have high miss rate – can lead to chronic problems

What injuries should you be watching for in children < 8 years? Occiput █ ~ atlanto-occipital dislocation C1 █ ~ C1-C2 subluxation C2 ~ odontoid fractures █ C3-C7 ~ ligamentous injury

References Patel et al: J Ped Surg 2001;36(2):373-376 Viccellio et al: Pediatrics 2001;108(2):e20 Kokoska et al: J Ped Surg 2001;36(1):100-105 Radiology Cases in Pediatric Emergency Medicine, University of Hawaii (www.hawaii.edu/medicine/pediatrics/pemxray) Laham et al: Ped Neurosurg 1994;21:221-226 Swischuk et al: Ped Radiol 2000;30:186-189 Buhs et al: J Ped Surg 2000;35(6):994-997 Ralston et al: Ped Emerg Care 2003;19(2):68-72 Ralston et al: Acad Emerg Med 2001;8(3):237-245 Keenan et al: AJR 2001;177:1405-1409 Keiper et al: Neurorad 1998;40(6):359-363 Dare et al J: Neurosurg 2002;97(suppl 1):33-39 Rose et al, Am J Surg 2003;185(4) The Encyclopaedia of Medical Imaging (www.amershamhealth.com) Proctor: Crit Care Med 2002;30(11)