Pediatric cervical spine: normal anatomy, variants, and trauma

Detection of pediatric cervical spine injury

OBJECTIVE

In evaluating the pediatric cervical spine for injury, the use of adult protocols without sufficient sensitivity to pediatric injury patterns may lead to excessive radiation doses. Data on injury location and means of detection can inform pediatric-specific guideline development.

METHODS

We retrospectively identified pediatric patients with codes from the International Classification of Diseases, 9th Revision, for cervical spine injury treated between 1980 and 2000. Collected data included physical findings, radiographic means of detection, and location of injury. Sensitivity of plain x-rays and diagnostic yield from additional radiographic studies were calculated.

RESULTS

Of 239 patients, 190 had true injuries and adequate medical records; of these, 187 had adequate radiology records. Patients without radiographic abnormality were excluded. In 34 children younger than 8 years, National Emergency X-Radiography Utilization Study criteria missed two injuries (sensitivity, 94%), with 76% of injuries occurring from occiput-C2. In 158 children older than 8 years, National Emergency X-Radiography Utilization Study criteria identified all injured patients (sensitivity, 100%), with 25% of injuries occurring from occiput-C2. For children younger than 8 years, plain-film sensitivity was 75% and combination plain-film/occiput-C3 computed tomographic scan had a sensitivity of 94%, whereas combination plain-film and flexion-extension views had 81% sensitivity. In patients older than 8 years, the sensitivities were 93%, 97%, and 94%, respectively.

CONCLUSION

Younger children tend to have more rostral (occiput-C2) injuries compared with older children. The National Emergency X-Radiography Utilization Study protocol may have lower sensitivity in young children than in adults. Limited computed tomography from occiput-C3 may increase diagnostic yield appreciably in young children compared with flexion-extension views. Further prospective studies, especially of young children, are needed to develop reliable pediatric protocols.

Pediatric cervical spine instability

Cervical spine instability in children is rare but not exceptional and may be due to many factors. Although it mostly occurs at the upper cervical spine, all vertebrae from the occiput to T1 may be involved. It may be acute or chronic, occurring secondary to trauma or due to congenital anomaly, skeletal or metabolic dystrophy or rheumatoid arthritis. It can be isolated or associated with other musculoskeletal or visceral anomalies. A thorough knowledge of embryology, anatomy, physiology and physiopathology of the cervical spine in children is essential to avoid pitfalls, recognize normal variants and identify children at risk of developing cervical spine instability and undertake the appropriate treatment.

Cervical spine trauma in the pediatric patient

Injuries to the pediatric cervical spine occur infrequently. Numerous unique anatomic and biomechanical features of the pediatric spine render it much more flexible than the adult spine. These features give rise to significant differences in the presentation, diagnosis, treatment, and prognosis of pediatric cervical trauma compared with adults. Younger children more often suffer injury to the upper cervical spine with greater neurologic injury and fewer fractures. Once the child reaches the age of 10 years, he or she develops a more adult-type spine, and injuries are thus more similar to those seen in the adult population. The unique anatomic and biomechanical differences in the pediatric spine are discussed, along with the various common and unique injuries.

Pattern, management and outcome of cervical spine injuries associated with head injuries in paediatric patients

INTRODUCTION

This study examines the management and outcome of cervical spine injuries in children with head injuries, to assess the need for surgical treatment.

MATERIAL AND METHODS

We performed a retrospective analysis (1995-2005) of 445 children admitted intubated and ventilated to the intensive care unit with head injuries.

OUTCOME MEASURES

Frankel grade for spinal injuries and Glasgow Outcome Scale (GOS) for head injuries.

RESULTS

Cervical spine injuries were detected in 11 patients (incidence 2.5%, mean age: 6.3 years, range: 21 months-15 years). The injuries were: C1/2 distraction: 2; C1/2 subluxation: 2; odontoid peg fracture with C1/2 dislocation and cord transection: 1; disruption of posterior longitudinal ligament at C2: 1; odontoid peg fracture with C2/3 distraction: 1; C2/3 subluxation: 1; C3 lamina fracture: 1; C3/4 facet fracture: 1; C6/7 fracture dislocation with cord transection: 1. One patient was managed operatively, ten patients nonoperatively, two with halo vests and eight with hard collars. There were three deaths (mortality 27%) associated with severe head injuries. At 6 months follow-up, two patients remained quadriplegic (Frankel Grade A), one of them ventilator dependent, one had residual motor function but of no practical use (Frankel Grade C), five had good spinal outcome (Frankel Grade E). Seven patients had good head injury outcomes (GOS 5), one remained disabled (GOS 3).

CONCLUSION

Most children with cervical injury can be managed nonoperatively with good outcomes. Surgical management may be necessary in severe unstable injuries.

Immature sheep spines are more flexible than mature spines: an in vitro biomechanical study

STUDY DESIGN

Dynamic triaxial biomechanical testing of immature and mature ovine spine motion segments.

OBJECTIVE

To compare torque-deflection parameters of mature and immature spine motion segments and to investigate whether scaling relationships apply between mature and immature motion segment torque-deflection responses.

SUMMARY OF BACKGROUND DATA

While previous studies have examined the cervical region in a limited number of loading directions, a comprehensive multiaxial study of the response of the pediatric spine at all 3 spinal levels (cervical, thoracic, and lumbar) has not been performed.

METHODS

Motion segments from cervical, thoracic, and lumbar levels were tested under moment application about 3 axes for newborn and 2-year-old sheep. Range of motion, neutral zone, and stiffness were calculated for each motion segment and compared for immature and mature spine.

RESULTS

Immature spine motion segments exhibited a significantly larger range of motion (P < 0.001) and neutral zone (P < 0.001) and significantly lower stiffness (P < 0.001) in comparison to mature spine segments about the 3 moment axes, at the 3 spinal levels tested. There were statistically significant interactions between specimen age and the moment axis and/or spinal level for some torque-deflection parameters.

CONCLUSION

The significantly greater neutral zone of immature spine suggests greater ligament laxity. Significantly higher range of motion and lower stiffness of the immature spine may be implicated in spinal cord injury mechanisms and implies a change in relative tolerance of the spine to damage with spinal maturity. Significant statistical interactions between spinal maturity and moment axis or motion segment level suggest that scaling torque-deflection parameters from mature to immature spine may not be appropriate.

Postnatal maturation and radiology of the growing spine

Postnatal maturation of the spine is marked by the ossification process and by changes in the shape of the vertebrae, spinal curvature, spinal canal, discs, and bone marrow. Different aspects of the spine's maturation process are demonstrated on the three most common radiologic modalities used to evaluate the spine. Conventional plain spine imaging (plain spine radiography) provides a good initial evaluation of the bony spine. CT provides better bone detail and allows finer evaluation of subtle structures, the soft tissues of the spine (discs, ligaments), and the spinal cord. MRI provides excellent resolution of the bone marrow, ligaments, and discs of the spine, and can be used as an adjunct for evaluating the soft tissue of the spine and intraspinal contents.

Digital radiographic measurement of the atlantodental interval in children

The atlantodental interval (ADI) is assessed after trauma to the head and neck region to determine whether the transverse ligament of the atlas is intact. Atlantodental interval measurement from conventional screen-film radiographs is characterized by the need for magnification correction and by low reliability. Assessment of normal ADI values using digital radiography with computer-assisted measurement has not been reported. We compared with published values the digital radiographic measurements of ADI in children, examined the reliability of measurements, and examined the interaction between age, sex and ADI. Computer-assisted digital measurements of ADI in 101 children, aged 1 to 12 years, were obtained from lateral supine head-neutral radiographs. We found intraobserver reliability of 0.72 and 0.85, interobserver reliability of 0.50, a maximum ADI value of 3.5 mm, no effect of sex and age, and weak evidence for an interaction between sex and age. Computer-assisted digital ADI measurement provides higher intraobserver reliability than what has previously been reported, and interobserver reliability and a maximum ADI value similar to that found in the literature.

Retroclival hematoma in the pediatric population. Report of two cases and review of the literature

Case reports of retroclival hematoma are infrequent, and little is known about the mechanism of formation of the lesion, its management strategy, and the outcome in affected patients. The authors report two cases of posttraumatic retroclival hematoma in children and discuss the available literature. Both patients were treated with cervical immobilization and had good outcomes. Retroclival hematomas are rare. Most reported cases involve pediatric patients in whom the hematomas developed in association with trauma. Spinal trauma in children mainly occurs at the craniovertebral junction due to a high fulcrum of cervical motion and results in ligamentous injuries more often than fractures. The formation of epidural hematomas posterior to the clivus is likely to be due to either clivus fracture or ligament disruption. A high index of suspicion is essential in making the diagnosis. Magnetic resonance imaging is superior to computed tomography in demonstrating retroclival hematomas because of its superiority in delineating the extradural spaces and the integrity of the ligaments. The authors conclude that in most cases retroclival hematomas can be treated conservatively and good outcomes can be expected.

[Spasmodic torticollis caused by metoclopramide: a rare etiology of C1-C2 rotatory pseudoluxation in children]

Torticollis in children must always instigate a search for trauma. Many other etiologies can be found. The authors report a case of postmedicinal atlantoaxial rotatory pseudoluxation (AARP) occurring in a child. This child had fallen down in the morning with head trauma followed by headache. Clinically, a stiff neck with an irreducible right rotation of his neck, and an osteotendinous hyperreflexia were noted. There was a C1-C2 rotatory dislocation with no traumatic lesion on the cervical CT scan. After a few hours, the torticollis spontaneously reduced and then reappeared on the left side. This clinical fluctuation and the absorption of metoclopramide (Primpéran) started in the morning for acute gastroenteritis provided the diagnosis of AARP. This entity was confirmed by the good clinical and radiological follow-up and was caused by the substantial ligament laxity of the craniovertebral junction encountered in children. The analysis of medical imaging and the systematic search for a medicinal cause helped make the right diagnosis.

Anterior approach to the subaxial cervical spine in children: a brief review

Although it was originally developed to address degenerative problems, including disc herniations and cervical spondylotic myelopathy in the adult population, the anterior approach to the subaxial spine has proven to be useful for select indications in the pediatric population. The authors review indications for surgery, bone grafting, and instrumentation as they pertain to children.

Developmental biomechanics of the cervical spine: Tension and compression

Epidemiological data and clinical indicia reveal devastating consequences associated with pediatric neck injuries. Unfortunately, neither injury prevention nor clinical management strategies will be able to effectively reduce these injuries or their effects on children, without an understanding of the cervical spine developmental biomechanics. Thus, we investigated the relationship between spinal development and the functional (stiffness) and failure biomechanical characteristics of the cervical spine in a baboon model. A correlation study design was used to define the relationships between spinal tissue maturation and spinal biomechanics in both tension and compression. Eighteen baboon cervical spine specimens distributed across the developmental spectrum (1-26 human equivalent years) were dissected into osteoligamentous functional spinal units. Using a servo-hydraulic MTS, these specimens (Oc-C2, C3-C4, C5-C6, C7-T1) were non-destructively tested in tension and compression and then displaced to failure in tension while measuring the six-axes of loads and displacements. The functions describing the developmental biomechanical response of the cervical spine for stiffness and normalized stiffness exhibited a significant direct relationship in both tension and compression loading. Similarly, the tensile failure load and normalized failure load demonstrated significant maturational increases. Further, differences in biomechanical response were observed between the spinal levels examined and all levels exhibited clinically relevant failure patterns. These data support our understanding of the child cervical spine from a developmental biomechanics perspective and facilitate the development of injury prevention or management schema for the mitigation of child spine injuries and their deleterious effects.

Subluxación atloaxoidea. “Os odontoideum”. Reducción y fijación posterior con alambres sublaminares en Cl anclados en tornillos pediculares de C2. Caso clínico

This report describes a case of atlanto-axial dislocation associated with os odontoideum. This 18-year-old male had a traumatic episode when he was 2 years old. As a result he suffered progressive chronic myelopathy on the verge of death. For the reduction and fixation of the atlanto-axial dislocation, sublaminar wires have been used anchored to C1 and to screws placed in the pedicles of C2. The authors present a surgical technique that has not been previously described.