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Cervical Spine Injuries in Children, Part II: Management and Special Considerations
The Journal of Emergency Medicine, Vol. 41, No. 3, pp. 252–256, 2011 Copyright © 2011 Elsevier Inc. Printed in the USA. All rights reserved 0736-4679/$–see front matter
doi:10.1016/j.jemermed.2010.03.018
Original Contributions CERVICAL SPINE INJURIES IN CHILDREN, PART II: MANAGEMENT AND SPECIAL CONSIDERATIONS Joshua S. Easter,
MD,*
Roger Barkin,
MD,†
Carlo L. Rosen,
MD,‡
and Kevin Ban,
MD§
*Department of Emergency Medicine, Children’s Hospital of Boston, Boston, Massachusetts, †Department of Pediatrics, University of Colorado, Denver, Colorado, ‡Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, §Pediatric Trauma Center at Meyer Hospital, Florence, Italy Reprint Address: Carlo L. Rosen, MD, Harvard Affiliated Emergency Medicine Residency, Beth Israel Deaconess Medical Center, One Deaconess Rd., West CC2, Boston, MA 02215
e Abstract—Background: The diagnosis and management of cervical spine injury is more complex in children than in adults. Objectives: Part I of this series stressed the importance of tailoring the evaluation of cervical spine injuries based on age, mechanism of injury, and physical examination findings. Part II will discuss the role of magnetic resonance imaging (MRI) as well as the management of pediatric cervical spine injuries in the emergency department. Discussion: Children have several common variations in their anatomy, such as pseudosubluxation of C2–C3, widening of the atlantodens interval, and ossification centers, that can appear concerning on imaging but are normal. Physicians should be alert for signs or symptoms of atlantorotary subluxation and spinal cord injury without radiologic abnormality when treating children with spinal cord injury, as these conditions have significant morbidity. MRI can identify injuries to the spinal cord that are not apparent with other modalities, and should be used when a child presents with a neurologic deficit but normal X-ray study or CT scan. Conclusion: With knowledge of these variations in pediatric anatomy, emergency physicians can appropriately identify injuries to the cervical spine and determine when further imaging is needed. © 2011 Elsevier Inc.
possess many normal anatomic variants not seen in adults, and they cannot provide complete histories or reliable physical examinations. In Part I of this series, we reviewed the important role of three-view radiographs, and the limited role of computed tomography (CT), in diagnosing cervical spine injuries. In Part II, we will review the role of magnetic resonance imaging (MRI) in the identification of injuries to the spinal cord. We will then discuss the basic management of any injuries identified by imaging. The review will conclude with an overview of injuries more common in children than adults, including spinal cord injury without radiographic abnormality and atlantoaxial rotary injuries. MAGNETIC RESONANCE IMAGING MRI plays a major role in the diagnosis of cervical spine injuries. It is better than plain film X-ray studies and CT scan at visualizing the soft tissues and identifying intervertebral disc herniation, ligamentous injury, and spinal cord edema or compression. The American Academy of Neurological Surgeons (AANS) recommends incorporating MRI to exclude spinal cord or root compression and to provide information about injury prognosis in pediatric patients. The absence of signal change within the spinal cord on T2-weighted images indicates an excellent prognosis, whereas hematomyelia or cord disruption suggests severe and permanent injury (1,2). In 52 children with normal
e Keywords— cervical spine; trauma; imaging; pediatric injury
INTRODUCTION It is often more difficult to diagnose cervical spine (Cspine) injures in children than in adults, because children
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plain films or CT scans but persistent or delayed symptoms, MRI identified previously undetectable injuries in 31% (3). Four of these 16 injuries required surgery. In each of the surgeries, the MRI helped the surgeon to operate at more levels than would have been detected based on symptoms or other imaging. The benefits of MRI in children were also seen in a retrospective analysis of 102 patients who underwent MRI when the C-spine could not be cleared with other imaging. In these patients, MRI reduced the time to C-spine clearance, reduced hospital stay by an average of 4.6 days, and provided a savings of nearly $7700 per patient (4). However, MRI should not be utilized alone, as it is not as sensitive as plain films or CT scan for identification of bony fractures (4).
MANAGEMENT Initial Immobilization When a cervical spine injury is suspected, appropriate immobilization must be achieved expediently. This is difficult in children because their heads are large in proportion to their torsos. This forces the head into flexion when a child is placed on a flat surface such as a spine board, potentially worsening any C-spine injury (5). In an analysis of 10 children ⬍ 7 years of age on a standard backboard, all had anterior angulations or translations of the spine (6). Placement in a cervical collar on the spine board does not necessarily prevent this angulation (7). Instead, correction of this misalignment requires elevation of the torso with a pad between the child and the spine board to eliminate neck flexion. The mean amount of elevation required is 2.5 cm. Children ⬍ 4 years of age require more elevation (5). The goal of elevation should be to align the patient’s external auditory meatus with the shoulders, as this eliminates flexion of the cervical spine (6). Alternatively, an occipital recess can correct this misalignment on the board (8). Taping across the torso may also help improve alignment; however, other studies have shown that this can reduce a patient’s forced vital capacity and thereby hinder respiratory function (9). Therefore, the ideal immobilization consists of placing a patient in a semi-rigid collar on a hard spine board with approximately 2.5 cm of elevation under the torso.
Emergency Assessment After appropriate stabilization of the patient, a thorough neurologic examination should be performed. The appearance of any deficits or gross injuries to the spine necessitates immediate consultation with a neurosurgeon or orthopedic surgeon. These subspecialists should have
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the opportunity to perform an examination as early in the patient’s course as possible, without delaying initial management of the airway and circulation by the emergency physician. Once the subspecialist has completed the examination, the appropriate imaging modality can be determined with assistance of the consultant.
Steroids There is significant controversy regarding the administration of steroids in spinal cord injury. The primary studies cited in support of administration of steroids in traumatic spinal cord injury are the National Association of Spinal Cord Injury Study trials (10). However, several problems exist with these studies. The primary effect, improvement in motor function, did not represent a clinically significant change. In addition, this effect was found only through post hoc analyses of the data. Finally, and most importantly with regards to pediatric spinal cord injury, the analyses excluded children. No trials have demonstrated a benefit of steroids in traumatic spinal cord injury in children. Given this lack of data, coupled with the controversy surrounding the administration of steroids in adults, steroid administration is not considered standard practice for pediatric spinal cord injuries.
SPECIAL CONSIDERATIONS Variability in Imaging Variations in the anatomy of the cervical spine further complicate the analysis of C-spine imaging in children (Table 1). Displacement of the cervical spine may be a normal variation in children, unlike in adults. For example, imaging frequently reveals pseudosubluxation of C2 on C3 in pediatric patients (Figure 1). A retrospective review of 138 children without trauma identified this pseudosubluxation on 22% of plain films (11). This phenomenon is more common in younger children, with 46% of normal children ⬍ 8 years of age having 3 mm or more of anterior-posterior displacement of C2 on C3 on flexion-extension X-ray studies (12). The dislocation of C2 on C3 can be differentiated from this pseudosubluxation by drawing Swischuk’s line, a line along the anterior aspect of the spinous processes of C1 and C3. This line should pass through, abut, or lay 2 mm anterior to the anterior spinous process of C2 (Figure 1). If this distance is more than 2 mm, it suggests a true dislocation of C2 on C3 and not pseudosubluxation (11). Children also may have displacement of the atlantodens space, with 20% of children ⬍ 7 years of age having an atlantodens interval, that is, distance between the anterior
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Table 1. Variations in the Anatomy of the Cervical Spine by Age in Pediatric Patients Age Less than 1 year 3 years
3–6 years
8 years 12–14 years 20 years
Variation in Anatomy Vertebral bodies wedged anteriorly No cervical lordosis C1 body not visible Dens ossifies Synchondroses of posterior spine fuse Differential growth of C1 on C2 (pseudoJefferson fracture) Ossification center at tip of odontoid (ossiculum terminale) Vertebral bodies no longer wedged anteriorly Three ossification centers each for C1–C7 (C2 can have four centers) Synchondrosis of body of C2 and odontoid Pseudosubluxation resolves Predens space ⬍ 5 mm Secondary ossification centers visible at tips of spinous processes Ossification center at tip of odontoid fuses Ossification centers on spinous processes fuse
aspect of the dens and the posterior aspect of the ring of the atlas, of 3 mm or greater, the upper limit of normal in adults (Figure 2) (12). When this interval is ⬎ 5 mm in children, it suggests the presence of ligamentous instability, atlantoaxial instability, a Jefferson fracture, or atlantoaxial rotatory
Figure 1. Pseudosubluxation of C2 on C3—2 mm of anterolisthesis of C2 on C3 is apparent. Swischuk’s line (solid line) shows the anterior aspect of the C2 spinous process is within 2 mm of this line, suggesting this is pseudosubluxation and not a dislocation of C2 on C3.
A B
Figure 2. Atlantodens interval—the distance between the anterior arch of the atlas (line labeled A) and anterior portion of the dens (line labeled B) should be < 5 mm.
subluxation (13). Children also frequently demonstrate spread of the atlas from the axis on the odontoid view. This pseudo-Jefferson fracture is particularly common in children ⬍ 4 years of age, in whom the lateral masses can displace as much as 6 mm from the dens in normal children (13). This arises from a discrepancy in the growth rate of the atlas compared to the axis (14). The intervertebral distance between C1 and C2 often can be wider than the other intervertebral distances in the normal pediatric cervical spine. This arises from the tight ligamentous attachments between the skull and C1 (15). Children also commonly have changes in the angulation of the spinal column that are normal variants. Fourteen percent of children do not have the normally expected cervical lordosis (12). Their vertebral bodies often show anterior wedging up to 3 mm, resembling compression fractures (16). This is particularly prominent at C3 in normal children due to repetitive force on the anterosuperior portion of the vertebral body of C3 (17). Children may have large prevertebral soft tissue spaces. The soft tissue space can expand up to 6 mm without injury, particularly with expiration or slight flexion of the spine. Ossification centers seen throughout childhood also make imaging difficult to interpret in the pediatric population. Knowledge of their characteristic locations and notation of their smooth corticated margins help differentiate ossification centers from fractures (Table 1). Pediatric patients may have three ossification centers at C1, the anterior arch and two neural arches. These fuse by 7 years of age, but before this, the separation between the three arches appears similar to a fracture (Figure 3) (18).
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Studies that include MRI analyses suggest SCIWORA is a much rarer problem; one retrospective review of nearly 20,000 pediatric trauma patients found a rate of ⬍ 1% (22). Others have suggested SCIWORA may not exist, with no children showing injury on MRI after normal X-ray studies (23). If it does exist, SCIWORA may arise as a result of a non-disruptive or self-reducing inter-segment deformity to the spinal cord. Alternatively, it could result from injury to the vascular supply of the spinal cord (24). It seems to be more common in children than adults, because their bony spinal columns are more elastic (25). Therefore, after flexion or extension injuries, their spinal cords are injured despite preservation of their spinal columns. After these injuries, patients typically will have delayed onset of neurologic symptoms ranging from 30 min to 4 days (20,26). Occasionally, the only symptom may be transient paresthesias at the time of the injury (21). Figure 3. Ossification center of C1—the small osseous fragment (arrow) anterior to C1 appears similar to a fracture but is an early ossification center.
There are four ossification centers at C2, the two neural arches, the body of C2, and the odontoid. The body of C2 fuses with the odontoid between 3 and 6 years of age, and this fusion produces a synchondrosis that is visible until 11 years of age and appears similar to a fracture (19). The os terminale at the tip of the odontoid is a secondary ossification center that forms between 3 and 6 years and closes by 12 years of age (Figure 4). C3 through C7 possess three ossification centers each, the two neural arches and the body. These fuse by 3 to 6 years of age. Secondary ossification centers can form at the tips of the transverse and spinous processes and can last until 30 years of age (19). These many variations in the anatomy of the pediatric cervical spine render interpretation of imaging by ED personnel difficult. As a result, when there is high clinical or radiographic suspicion for an injury, radiographs should be reviewed in consultation with a pediatric radiologist.
Atlantoaxial Rotary Injuries Children are also prone to atlantoaxial rotary subluxation and fixation. In the latter, the anterior facet of C1 becomes locked on the anterior facet of C2, preventing rotation around the joint. There are four variations: in type I, the atlas rotates unilaterally but the transverse ligament remains intact; in type II, C1 is displaced 2–5 mm anteriorly; in type III, C1 is displaced more than 5 mm anteriorly; and in type IV, C1 is posteriorly dis-
Spinal Cord Injury without Radiographic Abnormality Spinal cord injury without radiologic abnormality (SCIWORA) is an injury in which the objective signs of myelopathy exist without any finding on plain films or CT scan (20). Many reviews have estimated that SCIWORA occurs in as many as 67% of pediatric C-spine trauma patients (21). However, more recent analyses utilizing MRI suggest that many of the injuries previously attributed to SCIWORA are visible on MRI.
Figure 4. Ossification center of the odontoid—the three ossification centers present in children up to 7 years of age are often misdiagnosed as fractures.
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placed. In all of these classifications the patient cannot turn the head past midline and attempts to move the neck are painful. Despite this, the neurologic examination remains normal, and on plain films the atlantodens interval is normal (27). In contrast, on the odontoid view, one lateral mass of C1 can appear rotated forward as well as being wider and closer to the midline. On the lateral view, the lateral mass of C1 usually is rotated anteriorly to the odontoid, and on the anteroposterior view the spinous process may be rotated (8). If the diagnosis is not apparent based on the presentation and plain films, CT scan can be helpful in providing better visualization of the bony anatomy. This should be a dynamic scan during which the patient rotates the head as far as possible to the contralateral side, as static CT scanning is unable to differentiate subluxation from normal variants (28). This dynamic study is not easily performed with MRI. Upon diagnosis, if the injury is easily reducible, the patient can be placed in a rigid collar for 4 weeks. If the injury cannot be reduced, the AANS recommends waiting a week to determine if the injury will spontaneously reduce. If it does not spontaneously correct, then closed reduction can be performed followed by hard collar immobilization. A review of 20 children and another review of 23 children found that those presenting after 21 to 30 days were more prone to recurrent subluxation, and to require surgical correction (7). CONCLUSION Injury to the cervical spine of pediatric patients is different than to that of adults. Due to their anatomy, children are prone to different types and locations of injuries. These can be difficult to identify with a history or physical examination. As a result, most children with moderate to major trauma receive plain films of the cervical spine. These also are not straightforward, as children’s changing anatomy makes it difficult to determine which findings represent true abnormalities. Many of the findings require additional imaging to differentiate them further. In children over 8 years old, this differentiation can be accomplished with a cervical CT scan focused on the area of concern. In younger children, where the radiation associated with CT limits its use, knowledge of the common injuries to the pediatric C-spine as well as its unique anatomy can help emergency physicians identify cervical spine injuries in children accurately without additional radiation. This is crucial because delayed diagnosis results in high morbidity and mortality. REFERENCES 1. Davis PC, Reisner A, Hudgins PA, et al. Spinal injuries in children: role of MR. AJNR Am J Neuroradiol 1993;14:607–17.
2. Grabb PA, Pang D. Magnetic resonance imaging in the evaluation of spinal cord injury without radiographic abnormality in children. Neurosurgery 1994;35:406 –14; discussion 14. 3. Keiper MD, Zimmerman RA, Bilaniuk LT. MRI in the assessment of the supportive soft tissues of the cervical spine in acute trauma in children. Neuroradiology 1998;40:359 – 63. 4. Frank JB, Lim CK, Flynn JM, et al. The efficacy of magnetic resonance imaging in pediatric cervical spine clearance. Spine 2002;27:1176 –9. 5. Nypaver M, Treloar D. Neutral cervical spine positioning in children. Ann Emerg Med 1994;23:208 –11. 6. Herzenberg JE, Hensinger RN, Dedrick DK, Phillips WA. Emergency transport and positioning of young children who have an injury of the cervical spine. The standard backboard may be hazardous. J Bone Joint Surg Am 1989;71:15–22. 7. Treloar DJ, Nypaver M. Angulation of the pediatric cervical spine with and without cervical collar. Pediatr Emerg Care 1997;13:5– 8. 8. Management of pediatric cervical spine and spinal cord injuries. Neurosurgery 2002;50(3 Suppl):S85–99. 9. Huerta C, Griffith R, Joyce SM. Cervical spine stabilization in pediatric patients: evaluation of current techniques. Ann Emerg Med 1987;16:1121– 6. 10. Bracken MB, Shepard MJ, Collins WF Jr, et al. Methylprednisolone or naloxone treatment after acute spinal cord injury: 1-year follow-up data. Results of the second National Acute Spinal Cord Injury Study. J Neurosurg 1992;76:23–31. 11. Shaw M, Burnett H, Wilson A, et al. Pseudosubluxation of C2 on C3 in polytraumatized children—prevalence and significance. Clin Radiol 1999;54:377– 80. 12. Cattell HS, Filtzer DL. Pseudosubluxation and other normal variations in the cervical spine in children. A study of one hundred and sixty children. J Bone Joint Surg Am 1965;47:1295–309. 13. Roche C, Carty H. Spinal trauma in children. Pediatr Radiol 2001;31:677–700. 14. Budin E, Sondheimer F. Lateral spread of the atlas without fracture. Radiology 1966;87:1095– 8. 15. Bonadio WA. Cervical spine trauma in children: Part I. General concepts, normal anatomy, radiographic evaluation. Am J Emerg Med 1993;11:158 – 65. 16. 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– 45. 17. Eubanks JD, Gilmore A, Bess S, Cooperman DR. Clearing the pediatric cervical spine following injury. J Am Acad Orthop Surg 2006;14:552– 64. 18. Herman MJ, Pizzutillo PD. Cervical spine disorders in children. Orthop Clin North Am 1999;30:457– 66, ix. 19. Lustrin ES, Karakas SP, Ortiz AO, et al. Pediatric cervical spine: normal anatomy, variants, and trauma. Radiographics 2003;23:539–60. 20. Pang D, Pollack IF. Spinal cord injury without radiographic abnormality in children—the SCIWORA syndrome. J Trauma 1989;29:654–64. 21. Brown RL, Brunn MA, Garcia VF. Cervical spine injuries in children: a review of 103 patients treated consecutively at a level 1 pediatric trauma center. J Pediatr Surg 2001;36:1107–14. 22. Martin BW. Radiology in paediatric cervical spine injury. Emerg Med J 2004;21:648. 23. Viccellio P, Simon H, Pressman BD, et al. A prospective multicenter study of cervical spine injury in children. Pediatrics 2001;108:E20. 24. Akbarnia BA. Pediatric spine fractures. Orthop Clin North Am 1999;30:521–36, x. 25. Kriss VM, Kriss TC. SCIWORA (spinal cord injury without radiographic abnormality) in infants and children. Clin Pediatr (Phila) 1996;35:119 –24. 26. Hamilton MG, Myles ST. Pediatric spinal injury: review of 61 deaths. J Neurosurg 1992;77:705– 8. 27. Subach BR, McLaughlin MR, Albright AL, et al. Current management of pediatric atlantoaxial rotatory subluxation. Spine 1998; 23:2174 –9. 28. Kowalski HM, Cohen WA, Cooper P, et al. Pitfalls in the CT diagnosis of atlantoaxial rotary subluxation. AJR Am J Roentgenol 1987;149:595– 600.
doi:10.1016/j.jemermed.2010.03.018
Original Contributions CERVICAL SPINE INJURIES IN CHILDREN, PART II: MANAGEMENT AND SPECIAL CONSIDERATIONS Joshua S. Easter,
MD,*
Roger Barkin,
MD,†
Carlo L. Rosen,
MD,‡
and Kevin Ban,
MD§
*Department of Emergency Medicine, Children’s Hospital of Boston, Boston, Massachusetts, †Department of Pediatrics, University of Colorado, Denver, Colorado, ‡Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, §Pediatric Trauma Center at Meyer Hospital, Florence, Italy Reprint Address: Carlo L. Rosen, MD, Harvard Affiliated Emergency Medicine Residency, Beth Israel Deaconess Medical Center, One Deaconess Rd., West CC2, Boston, MA 02215
e Abstract—Background: The diagnosis and management of cervical spine injury is more complex in children than in adults. Objectives: Part I of this series stressed the importance of tailoring the evaluation of cervical spine injuries based on age, mechanism of injury, and physical examination findings. Part II will discuss the role of magnetic resonance imaging (MRI) as well as the management of pediatric cervical spine injuries in the emergency department. Discussion: Children have several common variations in their anatomy, such as pseudosubluxation of C2–C3, widening of the atlantodens interval, and ossification centers, that can appear concerning on imaging but are normal. Physicians should be alert for signs or symptoms of atlantorotary subluxation and spinal cord injury without radiologic abnormality when treating children with spinal cord injury, as these conditions have significant morbidity. MRI can identify injuries to the spinal cord that are not apparent with other modalities, and should be used when a child presents with a neurologic deficit but normal X-ray study or CT scan. Conclusion: With knowledge of these variations in pediatric anatomy, emergency physicians can appropriately identify injuries to the cervical spine and determine when further imaging is needed. © 2011 Elsevier Inc.
possess many normal anatomic variants not seen in adults, and they cannot provide complete histories or reliable physical examinations. In Part I of this series, we reviewed the important role of three-view radiographs, and the limited role of computed tomography (CT), in diagnosing cervical spine injuries. In Part II, we will review the role of magnetic resonance imaging (MRI) in the identification of injuries to the spinal cord. We will then discuss the basic management of any injuries identified by imaging. The review will conclude with an overview of injuries more common in children than adults, including spinal cord injury without radiographic abnormality and atlantoaxial rotary injuries. MAGNETIC RESONANCE IMAGING MRI plays a major role in the diagnosis of cervical spine injuries. It is better than plain film X-ray studies and CT scan at visualizing the soft tissues and identifying intervertebral disc herniation, ligamentous injury, and spinal cord edema or compression. The American Academy of Neurological Surgeons (AANS) recommends incorporating MRI to exclude spinal cord or root compression and to provide information about injury prognosis in pediatric patients. The absence of signal change within the spinal cord on T2-weighted images indicates an excellent prognosis, whereas hematomyelia or cord disruption suggests severe and permanent injury (1,2). In 52 children with normal
e Keywords— cervical spine; trauma; imaging; pediatric injury
INTRODUCTION It is often more difficult to diagnose cervical spine (Cspine) injures in children than in adults, because children
RECEIVED: 26 March 2010; ACCEPTED: 26 March 2010 252
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plain films or CT scans but persistent or delayed symptoms, MRI identified previously undetectable injuries in 31% (3). Four of these 16 injuries required surgery. In each of the surgeries, the MRI helped the surgeon to operate at more levels than would have been detected based on symptoms or other imaging. The benefits of MRI in children were also seen in a retrospective analysis of 102 patients who underwent MRI when the C-spine could not be cleared with other imaging. In these patients, MRI reduced the time to C-spine clearance, reduced hospital stay by an average of 4.6 days, and provided a savings of nearly $7700 per patient (4). However, MRI should not be utilized alone, as it is not as sensitive as plain films or CT scan for identification of bony fractures (4).
MANAGEMENT Initial Immobilization When a cervical spine injury is suspected, appropriate immobilization must be achieved expediently. This is difficult in children because their heads are large in proportion to their torsos. This forces the head into flexion when a child is placed on a flat surface such as a spine board, potentially worsening any C-spine injury (5). In an analysis of 10 children ⬍ 7 years of age on a standard backboard, all had anterior angulations or translations of the spine (6). Placement in a cervical collar on the spine board does not necessarily prevent this angulation (7). Instead, correction of this misalignment requires elevation of the torso with a pad between the child and the spine board to eliminate neck flexion. The mean amount of elevation required is 2.5 cm. Children ⬍ 4 years of age require more elevation (5). The goal of elevation should be to align the patient’s external auditory meatus with the shoulders, as this eliminates flexion of the cervical spine (6). Alternatively, an occipital recess can correct this misalignment on the board (8). Taping across the torso may also help improve alignment; however, other studies have shown that this can reduce a patient’s forced vital capacity and thereby hinder respiratory function (9). Therefore, the ideal immobilization consists of placing a patient in a semi-rigid collar on a hard spine board with approximately 2.5 cm of elevation under the torso.
Emergency Assessment After appropriate stabilization of the patient, a thorough neurologic examination should be performed. The appearance of any deficits or gross injuries to the spine necessitates immediate consultation with a neurosurgeon or orthopedic surgeon. These subspecialists should have
253
the opportunity to perform an examination as early in the patient’s course as possible, without delaying initial management of the airway and circulation by the emergency physician. Once the subspecialist has completed the examination, the appropriate imaging modality can be determined with assistance of the consultant.
Steroids There is significant controversy regarding the administration of steroids in spinal cord injury. The primary studies cited in support of administration of steroids in traumatic spinal cord injury are the National Association of Spinal Cord Injury Study trials (10). However, several problems exist with these studies. The primary effect, improvement in motor function, did not represent a clinically significant change. In addition, this effect was found only through post hoc analyses of the data. Finally, and most importantly with regards to pediatric spinal cord injury, the analyses excluded children. No trials have demonstrated a benefit of steroids in traumatic spinal cord injury in children. Given this lack of data, coupled with the controversy surrounding the administration of steroids in adults, steroid administration is not considered standard practice for pediatric spinal cord injuries.
SPECIAL CONSIDERATIONS Variability in Imaging Variations in the anatomy of the cervical spine further complicate the analysis of C-spine imaging in children (Table 1). Displacement of the cervical spine may be a normal variation in children, unlike in adults. For example, imaging frequently reveals pseudosubluxation of C2 on C3 in pediatric patients (Figure 1). A retrospective review of 138 children without trauma identified this pseudosubluxation on 22% of plain films (11). This phenomenon is more common in younger children, with 46% of normal children ⬍ 8 years of age having 3 mm or more of anterior-posterior displacement of C2 on C3 on flexion-extension X-ray studies (12). The dislocation of C2 on C3 can be differentiated from this pseudosubluxation by drawing Swischuk’s line, a line along the anterior aspect of the spinous processes of C1 and C3. This line should pass through, abut, or lay 2 mm anterior to the anterior spinous process of C2 (Figure 1). If this distance is more than 2 mm, it suggests a true dislocation of C2 on C3 and not pseudosubluxation (11). Children also may have displacement of the atlantodens space, with 20% of children ⬍ 7 years of age having an atlantodens interval, that is, distance between the anterior
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Table 1. Variations in the Anatomy of the Cervical Spine by Age in Pediatric Patients Age Less than 1 year 3 years
3–6 years
8 years 12–14 years 20 years
Variation in Anatomy Vertebral bodies wedged anteriorly No cervical lordosis C1 body not visible Dens ossifies Synchondroses of posterior spine fuse Differential growth of C1 on C2 (pseudoJefferson fracture) Ossification center at tip of odontoid (ossiculum terminale) Vertebral bodies no longer wedged anteriorly Three ossification centers each for C1–C7 (C2 can have four centers) Synchondrosis of body of C2 and odontoid Pseudosubluxation resolves Predens space ⬍ 5 mm Secondary ossification centers visible at tips of spinous processes Ossification center at tip of odontoid fuses Ossification centers on spinous processes fuse
aspect of the dens and the posterior aspect of the ring of the atlas, of 3 mm or greater, the upper limit of normal in adults (Figure 2) (12). When this interval is ⬎ 5 mm in children, it suggests the presence of ligamentous instability, atlantoaxial instability, a Jefferson fracture, or atlantoaxial rotatory
Figure 1. Pseudosubluxation of C2 on C3—2 mm of anterolisthesis of C2 on C3 is apparent. Swischuk’s line (solid line) shows the anterior aspect of the C2 spinous process is within 2 mm of this line, suggesting this is pseudosubluxation and not a dislocation of C2 on C3.
A B
Figure 2. Atlantodens interval—the distance between the anterior arch of the atlas (line labeled A) and anterior portion of the dens (line labeled B) should be < 5 mm.
subluxation (13). Children also frequently demonstrate spread of the atlas from the axis on the odontoid view. This pseudo-Jefferson fracture is particularly common in children ⬍ 4 years of age, in whom the lateral masses can displace as much as 6 mm from the dens in normal children (13). This arises from a discrepancy in the growth rate of the atlas compared to the axis (14). The intervertebral distance between C1 and C2 often can be wider than the other intervertebral distances in the normal pediatric cervical spine. This arises from the tight ligamentous attachments between the skull and C1 (15). Children also commonly have changes in the angulation of the spinal column that are normal variants. Fourteen percent of children do not have the normally expected cervical lordosis (12). Their vertebral bodies often show anterior wedging up to 3 mm, resembling compression fractures (16). This is particularly prominent at C3 in normal children due to repetitive force on the anterosuperior portion of the vertebral body of C3 (17). Children may have large prevertebral soft tissue spaces. The soft tissue space can expand up to 6 mm without injury, particularly with expiration or slight flexion of the spine. Ossification centers seen throughout childhood also make imaging difficult to interpret in the pediatric population. Knowledge of their characteristic locations and notation of their smooth corticated margins help differentiate ossification centers from fractures (Table 1). Pediatric patients may have three ossification centers at C1, the anterior arch and two neural arches. These fuse by 7 years of age, but before this, the separation between the three arches appears similar to a fracture (Figure 3) (18).
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Studies that include MRI analyses suggest SCIWORA is a much rarer problem; one retrospective review of nearly 20,000 pediatric trauma patients found a rate of ⬍ 1% (22). Others have suggested SCIWORA may not exist, with no children showing injury on MRI after normal X-ray studies (23). If it does exist, SCIWORA may arise as a result of a non-disruptive or self-reducing inter-segment deformity to the spinal cord. Alternatively, it could result from injury to the vascular supply of the spinal cord (24). It seems to be more common in children than adults, because their bony spinal columns are more elastic (25). Therefore, after flexion or extension injuries, their spinal cords are injured despite preservation of their spinal columns. After these injuries, patients typically will have delayed onset of neurologic symptoms ranging from 30 min to 4 days (20,26). Occasionally, the only symptom may be transient paresthesias at the time of the injury (21). Figure 3. Ossification center of C1—the small osseous fragment (arrow) anterior to C1 appears similar to a fracture but is an early ossification center.
There are four ossification centers at C2, the two neural arches, the body of C2, and the odontoid. The body of C2 fuses with the odontoid between 3 and 6 years of age, and this fusion produces a synchondrosis that is visible until 11 years of age and appears similar to a fracture (19). The os terminale at the tip of the odontoid is a secondary ossification center that forms between 3 and 6 years and closes by 12 years of age (Figure 4). C3 through C7 possess three ossification centers each, the two neural arches and the body. These fuse by 3 to 6 years of age. Secondary ossification centers can form at the tips of the transverse and spinous processes and can last until 30 years of age (19). These many variations in the anatomy of the pediatric cervical spine render interpretation of imaging by ED personnel difficult. As a result, when there is high clinical or radiographic suspicion for an injury, radiographs should be reviewed in consultation with a pediatric radiologist.
Atlantoaxial Rotary Injuries Children are also prone to atlantoaxial rotary subluxation and fixation. In the latter, the anterior facet of C1 becomes locked on the anterior facet of C2, preventing rotation around the joint. There are four variations: in type I, the atlas rotates unilaterally but the transverse ligament remains intact; in type II, C1 is displaced 2–5 mm anteriorly; in type III, C1 is displaced more than 5 mm anteriorly; and in type IV, C1 is posteriorly dis-
Spinal Cord Injury without Radiographic Abnormality Spinal cord injury without radiologic abnormality (SCIWORA) is an injury in which the objective signs of myelopathy exist without any finding on plain films or CT scan (20). Many reviews have estimated that SCIWORA occurs in as many as 67% of pediatric C-spine trauma patients (21). However, more recent analyses utilizing MRI suggest that many of the injuries previously attributed to SCIWORA are visible on MRI.
Figure 4. Ossification center of the odontoid—the three ossification centers present in children up to 7 years of age are often misdiagnosed as fractures.
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placed. In all of these classifications the patient cannot turn the head past midline and attempts to move the neck are painful. Despite this, the neurologic examination remains normal, and on plain films the atlantodens interval is normal (27). In contrast, on the odontoid view, one lateral mass of C1 can appear rotated forward as well as being wider and closer to the midline. On the lateral view, the lateral mass of C1 usually is rotated anteriorly to the odontoid, and on the anteroposterior view the spinous process may be rotated (8). If the diagnosis is not apparent based on the presentation and plain films, CT scan can be helpful in providing better visualization of the bony anatomy. This should be a dynamic scan during which the patient rotates the head as far as possible to the contralateral side, as static CT scanning is unable to differentiate subluxation from normal variants (28). This dynamic study is not easily performed with MRI. Upon diagnosis, if the injury is easily reducible, the patient can be placed in a rigid collar for 4 weeks. If the injury cannot be reduced, the AANS recommends waiting a week to determine if the injury will spontaneously reduce. If it does not spontaneously correct, then closed reduction can be performed followed by hard collar immobilization. A review of 20 children and another review of 23 children found that those presenting after 21 to 30 days were more prone to recurrent subluxation, and to require surgical correction (7). CONCLUSION Injury to the cervical spine of pediatric patients is different than to that of adults. Due to their anatomy, children are prone to different types and locations of injuries. These can be difficult to identify with a history or physical examination. As a result, most children with moderate to major trauma receive plain films of the cervical spine. These also are not straightforward, as children’s changing anatomy makes it difficult to determine which findings represent true abnormalities. Many of the findings require additional imaging to differentiate them further. In children over 8 years old, this differentiation can be accomplished with a cervical CT scan focused on the area of concern. In younger children, where the radiation associated with CT limits its use, knowledge of the common injuries to the pediatric C-spine as well as its unique anatomy can help emergency physicians identify cervical spine injuries in children accurately without additional radiation. This is crucial because delayed diagnosis results in high morbidity and mortality. REFERENCES 1. Davis PC, Reisner A, Hudgins PA, et al. Spinal injuries in children: role of MR. AJNR Am J Neuroradiol 1993;14:607–17.
2. Grabb PA, Pang D. Magnetic resonance imaging in the evaluation of spinal cord injury without radiographic abnormality in children. Neurosurgery 1994;35:406 –14; discussion 14. 3. Keiper MD, Zimmerman RA, Bilaniuk LT. MRI in the assessment of the supportive soft tissues of the cervical spine in acute trauma in children. Neuroradiology 1998;40:359 – 63. 4. Frank JB, Lim CK, Flynn JM, et al. The efficacy of magnetic resonance imaging in pediatric cervical spine clearance. Spine 2002;27:1176 –9. 5. Nypaver M, Treloar D. Neutral cervical spine positioning in children. Ann Emerg Med 1994;23:208 –11. 6. Herzenberg JE, Hensinger RN, Dedrick DK, Phillips WA. Emergency transport and positioning of young children who have an injury of the cervical spine. The standard backboard may be hazardous. J Bone Joint Surg Am 1989;71:15–22. 7. Treloar DJ, Nypaver M. Angulation of the pediatric cervical spine with and without cervical collar. Pediatr Emerg Care 1997;13:5– 8. 8. Management of pediatric cervical spine and spinal cord injuries. Neurosurgery 2002;50(3 Suppl):S85–99. 9. Huerta C, Griffith R, Joyce SM. Cervical spine stabilization in pediatric patients: evaluation of current techniques. Ann Emerg Med 1987;16:1121– 6. 10. Bracken MB, Shepard MJ, Collins WF Jr, et al. Methylprednisolone or naloxone treatment after acute spinal cord injury: 1-year follow-up data. Results of the second National Acute Spinal Cord Injury Study. J Neurosurg 1992;76:23–31. 11. Shaw M, Burnett H, Wilson A, et al. Pseudosubluxation of C2 on C3 in polytraumatized children—prevalence and significance. Clin Radiol 1999;54:377– 80. 12. Cattell HS, Filtzer DL. Pseudosubluxation and other normal variations in the cervical spine in children. A study of one hundred and sixty children. J Bone Joint Surg Am 1965;47:1295–309. 13. Roche C, Carty H. Spinal trauma in children. Pediatr Radiol 2001;31:677–700. 14. Budin E, Sondheimer F. Lateral spread of the atlas without fracture. Radiology 1966;87:1095– 8. 15. Bonadio WA. Cervical spine trauma in children: Part I. General concepts, normal anatomy, radiographic evaluation. Am J Emerg Med 1993;11:158 – 65. 16. 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– 45. 17. Eubanks JD, Gilmore A, Bess S, Cooperman DR. Clearing the pediatric cervical spine following injury. J Am Acad Orthop Surg 2006;14:552– 64. 18. Herman MJ, Pizzutillo PD. Cervical spine disorders in children. Orthop Clin North Am 1999;30:457– 66, ix. 19. Lustrin ES, Karakas SP, Ortiz AO, et al. Pediatric cervical spine: normal anatomy, variants, and trauma. Radiographics 2003;23:539–60. 20. Pang D, Pollack IF. Spinal cord injury without radiographic abnormality in children—the SCIWORA syndrome. J Trauma 1989;29:654–64. 21. Brown RL, Brunn MA, Garcia VF. Cervical spine injuries in children: a review of 103 patients treated consecutively at a level 1 pediatric trauma center. J Pediatr Surg 2001;36:1107–14. 22. Martin BW. Radiology in paediatric cervical spine injury. Emerg Med J 2004;21:648. 23. Viccellio P, Simon H, Pressman BD, et al. A prospective multicenter study of cervical spine injury in children. Pediatrics 2001;108:E20. 24. Akbarnia BA. Pediatric spine fractures. Orthop Clin North Am 1999;30:521–36, x. 25. Kriss VM, Kriss TC. SCIWORA (spinal cord injury without radiographic abnormality) in infants and children. Clin Pediatr (Phila) 1996;35:119 –24. 26. Hamilton MG, Myles ST. Pediatric spinal injury: review of 61 deaths. J Neurosurg 1992;77:705– 8. 27. Subach BR, McLaughlin MR, Albright AL, et al. Current management of pediatric atlantoaxial rotatory subluxation. Spine 1998; 23:2174 –9. 28. Kowalski HM, Cohen WA, Cooper P, et al. Pitfalls in the CT diagnosis of atlantoaxial rotary subluxation. AJR Am J Roentgenol 1987;149:595– 600.