Pediatric spinal trauma

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Why is it important to consider the normal growth and development of the spine when evaluating a child with a suspected spinal injury?

Knowledge of the developmental anatomy of the spine is important to avoid misdiagnosis of anatomic differences such as normal physes, synchondroses, and secondary ossification centers as acute fractures.

• The atlas (C1) is formed from three ossification centers: the anterior arch and two posterior neural arches. The anterior arch is ossified in only 20% of newborns.

• The axis (C2) is formed from five primary ossification centers. The area between the odontoid process and C2 body (dentocentral synchondrosis) commonly fuses by 6 years of age and may be confused with a fracture before this age. The secondary ossification center at the tip of the odontoid, the ossiculum terminale, typically fuses by age 12.

• The subaxial cervical spine (C3–C7) and the thoracic and lumbar spine develop in a similar pattern from three primary ossification centers. Secondary ossification centers can form at the tips of the spinous processes, transverse processes, and superior and inferior vertebral margins and may be misdiagnosed as fractures.

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What are some anatomic differences between the immature and the adult spine that influence patterns of spinal injury that occur in the pediatric population?

The capacity for growth and the potential for injury to the growth plate differentiate pediatric and adult spine trauma patients and contribute to the complexity of evaluation of the pediatric spine trauma patient. Unique anatomic features of the immature spine include:

• Hypermobility

• Hyperlaxity of ligamentous and capsular structures

• Presence of epiphyses and synchondroses

• Incomplete ossification

• Unique configuration of the vertebral bony elements (e.g., wedge-shaped vertebral bodies, horizontal cervical facet joints)

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What are the most common injury mechanisms in children who sustain significant spine trauma?

Motor vehicle accidents, falls, and sports-associated injuries. Birth injuries and nonaccidental injury (child abuse) are less common but important injury mechanisms to consider.

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What are the relative strengths and weaknesses of plain radiographs, computed tomography (CT) scan, and magnetic resonance imaging (MRI) in the detection of spine injuries in pediatric patients?

• Radiographs: Plain radiographs play a role in the initial imaging evaluation of the spine-injured pediatric patient. A cervical spine series consists of anteroposterior (AP) and lateral views. The lateral radiograph must clearly visualize the C7–T1 level. The open-mouth AP odontoid view is difficult to obtain in an uncooperative child and has not been shown to provide important additional information in children less than age 9. AP and lateral radiographs of the thoracic and lumbar spine are obtained if there is concern regarding injury to these spinal regions. If faced with equivocal findings or an uncooperative child with a mechanism of injury or physical examination that is suspicious for spinal injury, more advanced imaging is indicated as studies have documented that plain radiographs fail to diagnose 25%–75% of pediatric spinal injuries, especially injuries involving unossified tissues and soft tissues such as ligaments, joint capsules, intervertebral discs, and cartilaginous endplates.

• CT scans: The use of helical CT scanning for screening for spinal injury in the pediatric polytrauma patient has increased due to the high sensitivity of CT compared to plain radiography for detection of osseous injury. However, radiation exposure and future cancer risk due to organ sensitivity and longer life expectancy of pediatric patients are important concerns that limit widespread use of CT in the pediatric population.

• MRI: Advantages of MRI include lack of exposure to ionizing radiation and the ability to assess neurologic structures and detect injuries to soft tissue and unossified structures that are not detected with plain radiographs or CT scan. However, it may be challenging to obtain an expeditious MRI for evaluation of the pediatric polytrauma patient due to logistical considerations, including the frequent need for sedation during image acquisition.

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How does a child’s age affect the pattern of traumatic spine injury?

In neonates, birth trauma is the most common cause of spinal injury. In infants and young children (<3 years), nonaccidental (child abuse) and accidental trauma are common causes of injury. Prior to 8 years of age, pediatric patients have a high head-to-body ratio that predisposes children to upper cervical injury (C3 or above). These injuries are associated with a notable rate of neurologic injury and fatality. After age 8 years, injury patterns most commonly involve the subaxial cervical region and the thoracic and lumbar regions, with the most commonly injured region of the vertebral column located between L2 and the sacrum.

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What characteristic findings are noted in a child who has sustained a spine injury as a result of child abuse?

Spine fractures due to nonaccidental trauma are most commonly reported in patients less than 2 years of age. These injuries may involve all regions of the spine, but are more common in the upper cervical region. Multilevel spinal injuries and neurologic injury are present in over half of these patients. Spinal injuries most often involve the vertebral bodies, with varying degrees of anterior compression, frequently involving multiple spinal levels. Avulsion fractures of the spinous processes, pars fractures, pedicle fractures, ligament injuries, anterior notching of the vertebral body near the superior endplate, decreased disc height caused by disc herniation and fracture-dislocation may be present ( Fig. 43.1 ). Other stigmata that suggest child abuse include fractures involving the skull, ribs, and long bones, as well as soft tissue injuries.

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What maternal risk factors are related to neonatal spinal cord injury?

The risk factors include small pelvic dimensions, obesity, prolonged delivery, forceps use, and shoulder dystocia. Early clinical findings that suggest a spinal cord injury include severe respiratory compromise and profound hypotonia. It should be noted that brachial plexus injury is far more common than spinal cord injury (i.e., Erb [C5/C6] or Klumpke [C7/T1] palsy). Detailed physical examination and MRI are critical in making this distinction.

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What is SCIWORA?

SCIWORA is an acronym for s pinal c ord i njury w ith o ut r adiographic a bnormality, and is defined as an injury to the spinal cord without visible changes on plain radiographs or CT. Due to the variable elasticity of the spinal column in children, forces applied to the spine may be accommodated by the spinal column but exceed the elastic limit of the spinal cord and manifest as a stretch injury to the spinal cord. It has been demonstrated that the spinal column of an infant can be stretched up to 2 inches, whereas the spinal cord can be stretched only 0.25 inches before rupturing. MRI is the imaging study of choice to diagnose patients with suspected SCIWORA as this imaging modality can demonstrate injury to the spinal cord and unossified tissues. Characteristic MRI findings include acute hemorrhage and edema of the spinal cord, ligamentous injury, disc herniation, and physeal injuries. SCIWORA most commonly involves the cervical region and cervicothoracic junction. Thoracolumbar involvement is less common but may occur in association with high-energy trauma, and typically involves the watershed region of the cord. SCIWORA injuries are treated as potentially unstable injuries as initial spinal column displacement may spontaneously reduce. Delayed-onset SCIWORA may be seen up to 4 days after injury in the setting of ligamentous instability. Brace immobilization up to 12 weeks is recommended for patients with SCIWORA. Although uncommon, recurrent SCIWORA after an initial period of neurologic stabilization may occur days to weeks after injury and may be prevented with immobilization.

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How does the addition of a shoulder harness to a lap belt influence the type of spinal injury sustained by a pediatric motor vehicle passenger?

Use of a lap belt in isolation permits the belt to act as an anterior fulcrum leading to a flexion-distraction injury mechanism in the thoracolumbar spine. The addition of a shoulder harness to a lap belt reduces this injury pattern by limiting forward flexion of the thorax during impact and reducing flexion-distraction forces on the lumbar spine. However, by restraining the thorax, a shoulder harness can increase the risk of cervical spine injuries in severe accidents. Less commonly, the shoulder harness of seat belts may be associated with injuries to the supraaortic vessels (carotid and subclavian) in association with first and second rib fractures.

10

What is the correct way to immobilize a child during initial evaluation of a suspected traumatic cervical spine injury?

Because children have a large cranium in relation to their thorax, immobilization on a standard spine board will place the cervical spine in a flexed position. Use of a double mattress to elevate the thorax or use of a pediatric spine board with a recess for the occiput is recommended to avoid undesirable displacement of cervical injuries.

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