Spinal Injuries - Clinical Tree

The author wishes to acknowledge the contribution of John A. Herring for his work in the previous edition version of this chapter.

Traumatic Injuries of the Cervical Spine

Cervical spine injuries are rare in children and are often difficult to diagnose because of an inability to obtain a clear history and the difficulty of imaging an immature spine. Therefore, a high index of suspicion is necessary to avoid missing the diagnosis and incurring associated sequelae. Neurologic injury may be present, despite negative imaging studies. The patterns of injury in children older than 10 years are similar to those in adults, with a greater incidence of subaxial injuries than in younger children, in whom injuries more frequently occur between the occiput and C2. Most injuries do not result in neurologic injury, and nonoperative treatment usually is effective.

Anatomy

Three ossification centers are present in the immature atlas: one for the anterior ring, which usually appears by 1 year of age, and one each for the posterior neural arches. The connection between the anterior and posterior arches is composed of the neurocentral synchondroses, which fuse at 7 years of age and can be mistaken for fracture before this period. The posterior arch usually closes by the age of 3 years but can remain open or partially closed ( Fig. 28.1 ).

Fig. 28.1, Ossification centers of the atlas. Note the neurocentral synchondroses between the anterior ring and posterior neural arches.

The ossification centers of the axis include one for the body, one for each neural arch, and one for the dens ( Fig. 28.2 ). Fusion of the dens to the neural arches and the anterior body occurs between 3 and 6 years of age. During fetal development, the dens is formed from two ossification centers, which fuse during the seventh month of gestation. An ossification center at the tip of the odontoid appears between 4 and 6 years of age and fuses to the remaining odontoid by the age of 12 years. The lower cervical vertebrae follow a similar pattern of development; the ossification centers at the body and each neural arch closes by the third year, and the neurocentral synchondroses fuse between the fourth and sixth years.

Fig. 28.2, Schematic sagittal (A) and axial (B) views of the ossification centers of the axis. The four centers of ossification are depicted. The anterior arch is comprised of the body and the dens, whereas two neural arches comprise the remaining centers of ossification.

The blood supply to the odontoid is derived from the anterior and posterior ascending arteries, which branch from the vertebral arteries at the level of the third cervical vertebra and coalesce in the midline. Anastomoses between the carotid and ascending arteries occur near the apex of the odontoid process.

Epidemiology

Although cervical spine fractures in children account for a small percentage of all cervical spine fractures, cervical spine injuries account for most spine injuries in children, with up to 48% of all spine fractures in children occurring in the cervical spine. ^, ^,

In contrast to what is seen in adults, most cervical spine injuries in young children occur between the occiput and C2 because of increased ligamentous laxity and hypermobility, together with a relatively larger head size, resulting in the fulcrum of injury being above C3. ^a

a References , , , , , , , , .

Atlas and axis injuries accounted for 16% of cervical spine injuries in a large series of adults, compared with 70% in children. As the child gets older and takes on a more adult body habitus, the incidence of cervical spine injuries is more similar to the adult pattern. ^b

b References , , , , , .

The mechanism of injury depends on the age of the child. Obstetric cervical spine injury can occur, particularly in infants with hyperextension of the head in the breech presentation. Cesarean delivery may prevent this catastrophic complication. ^, ^, ^, Infants with cervical spine injury are most commonly the victims of nonaccidental trauma, usually violent shaking. ^c

c References , , , , , .

Careful clinical evaluation is important in this age group because a significant number of these injuries may have normal plain radiographs, or spinal cord injury (SCI) without radiographic abnormality (SCIWORA; see later, “Spinal Cord Injury Without Radiographic Abnormality”). ^d

d References , , , , , , , , .

In older children, cervical spine injuries are more often caused by motor vehicle accidents (MVAs), pedestrian–motor vehicle encounters, falls from heights, trampoline injuries, all-terrain vehicle (ATV) accidents, and athletic injuries. ^e

e References , , , , , , , , , , , , , .

Diagnosis

Every child evaluated after a traumatic event should be questioned about the mechanism of injury and assessed for injury to the cervical spine. Risk factors for cervical spine injury include facial abrasions or lacerations, head trauma, clavicle fractures, high-speed MVAs, and falls from a height. Painful torticollis may be present in an alert child with a cervical spine injury.

Physical examination should include a head-to-toe assessment by the entire trauma team. The head and face should be carefully inspected for lacerations and abrasions. The neck should be palpated to elicit tenderness, muscle guarding, or the presence of a gap in the spinous processes, which would indicate a posterior ligamentous injury. A complete orthopaedic assessment of all four extremities and of the remainder of the spine and pelvis should be performed. A thorough neurologic examination must be performed and should include a rectal examination when a neurologic injury is suspected. The importance of a thorough and careful examination cannot be overstated inasmuch as additional orthopaedic injuries have been reported to occur in up to 40% of children with cervical spine injuries, and closed head injuries have been reported in 58% of cases. ^, ^,

A child who arrives in the emergency department unconscious is always considered to have a cervical spine injury. The child should wear a cervical collar to stabilize the cervical spine until the patient is awake and can cooperate with the physical examination. ^, A cervical spine injury should be strongly suspected when clonus is present in the extremities without decerebrate rigidity. Surgeons should remember the importance of distracting injuries, particularly other fractures. With especially severe trauma, usually from an MVA, cervical arterial injury may occur, 11% in one series, and computed tomography (CT) angiography or magnetic resonance (MR) angiography should be considered.

Concerns for potential missed injuries, complications related to prolonged immobilization in a soft collar, and radiation exposure have led to considerable work to develop standardized protocols for clearing the cervical spine in traumatically injured children. ^f

f References , , , , , , , .

Radiographic Findings

A radiographic evaluation should be performed when a cervical spine injury is suspected. The two best predictors of cervical spine injury have been described as involvement in an MVA and complaints of neck pain. However, we usually obtain radiographs in any patient with cervical tenderness, distracting injuries, altered mental status, alcohol or drug intoxication, or a neurologic deficit.

Cervical Spine Radiographs

Although plain radiographic assessment of the child may be difficult, up to 98% of injuries can be diagnosed on lateral cervical spine radiographs, so careful assessment of good-quality radiographs is the critical first step in the evaluation of children with cervical spine injury. In an unstable patient, a screening lateral radiograph of the cervical spine obtained in the emergency department should be viewed as an initial screening test, and additional views should be obtained when the condition of the patient allows ( Fig. 28.3 ). A complete radiographic examination should include anteroposterior (AP), lateral, open-mouth, and oblique views. When injury is suspected despite normal-appearing radiographs, flexion-extension lateral radiographs should be obtained to help identify pathology ( Fig. 28.4 ). When one injury is identified, it is important to obtain and carefully examine radiographs of the entire spine because multiple sites of injury may be present. The reported frequency of injury to other spinal segments in children with cervical spine (C-spine) injuries ranges from 4% to 35%.

Fig. 28.3, Screening lateral radiograph of the cervical spine. The radiograph should show all seven cervical vertebrae and also include the C7–T1 level.

Fig. 28.4, (A and B) Flexion-extension lateral radiographs.

The lateral radiograph should be examined systematically, with the examiner looking first for alignment:

1.
Alignment is checked by following the anterior and posterior lines of the vertebral bodies or the spinolaminar line described by Swischuk and Rowe ( Fig. 28.5 ). ^, This line is more important diagnostically than the line connecting the anterior and posterior lines of the vertebral bodies, which may exhibit a step-off, especially at the C2–4 levels.
2.
The posterior interspinous process distance should be assessed. Posterior ligamentous instability is manifested on the lateral radiograph by an increase in the interspinous distance, loss of parallelism between the articular processes, and posterior widening of the disk space ( Fig. 28.6 ).
3.
The prevertebral soft tissue width should be measured; normally, it is less than 5 to 6 mm anterior to the body of C2.
4.
Cervical lordosis should be examined. Although loss of cervical lordosis does not denote the presence of cervical spine injury, it may indicate muscle guarding and spasm.
5.
Because children have a higher incidence of injuries between the occiput and C3, it is important to evaluate this area carefully and obtain a good open-mouth view.

Accepted criteria for instability of the upper cervical spine in children include more than 10 degrees of forward flexion of C1 on C2 and an atlanto-dens interval (ADI) greater than 4 mm. The upper limit of the ADI in children has been suggested to be 3 ± 0.7 mm in flexion, with less than 0.5 mm of difference in ADI between flexion and extension radiographs. In adults, the transverse ligament is considered ruptured when the ADI is between 3 and 5 mm, and the transverse and alar ligaments are ruptured when the ADI is 10 to 12 mm. In the lower cervical spine, no accepted criteria have been developed for children; however, in adults, the accepted amount of angulation between the affected vertebra and adjacent segment is 11 degrees. ^, ^,

Pseudosubluxation refers to forward translation of the anterior aspect of the vertebral body relative to the inferior level, despite normal alignment of the posterior spinolaminar line (Swischuk line, see Fig. 28.5 ). This well-described radiographic variant is a result of normal physiologic development of the cervical spine. In the upper cervical spine of young patients, the facet joints are more horizontal. With growth, the facets become more vertical. Forward displacement of up to 4 mm at C2-3 is normal in children and is usually seen in those younger than 8 years ( Fig. 28.7 ). ^, ^, ^, ^,

Fig. 28.7, Pseudosubluxation of the cervical spine in children. On the lateral radiograph there is apparent subluxation of the vertebral bodies of C2 and C3. It appears that C2 is anteriorly subluxed on C3 (arrow) ; however, when the spinal laminar line of Swischuk is drawn, there is no true subluxation.

Other Studies

Further imaging studies, including CT or MRI, are indicated when abnormalities are seen on the initial plain radiographs and when a cervical spine injury is suspected despite normal radiographs. CT is best used for children suspected of having osseous fractures, facet dislocations, or vertebral endplate fractures. ^, When fractures extend into the transverse foramina, and with severe subluxations, noninvasive angiography should be considered to discover vascular injuries. MR imaging (MRI) is best used to evaluate soft tissue injuries, including posterior ligamentous injury, a herniated disk, encroachment of the neuroforamina, spinal cord lesions and edema, and a posttraumatic spinal cord cyst. MRI may have some prognostic value in distinguishing patients with spinal cord edema, who generally recover neurologically, from patients with intraspinal hemorrhage, who often do not recover. MRI may also be useful for demonstrating injuries to the spinal cord that are remote from the bony injury.

A number of studies have assessed the role of CT and MRI scans to clear the cervical spine in adults and children with altered mental status or a distracting injury. Both these modalities have been shown to be highly sensitive and specific in identifying occult injury. These screening protocols have been shown to decrease the length of hospital stay and may be more effective than dynamic radiographs. Although many protocols have been proposed, there is no universally accepted standard to date. ^g

g References , , , , , , , , , , .

Frank and co-workers reported the results of a protocol to use MRI for clearing the cervical spine in obtunded and intubated pediatric trauma patients who could not be cleared within 72 hours. They reported decreased time to clearance of the cervical spine and decreased length of stay and believed that the MRI protocol was effective and cost-efficient.

Treatment

Because a child’s head is proportionally larger than the body, positioning the patient to prevent acute flexion of the neck is important during transport and evaluation. Adult proportions begin to emerge in children at 8 years of age. Anterior angulation or translation on lateral radiographs have been identified in young children with unstable C-spine injuries when positioned on a traditional backboard ( Fig. 28.8A ), so a bed or backboard with a posterior recess to allow posterior positioning of the head is recommended to prevent flexion of the cervical spine (see Fig. 28.8B ). Initially, the child should be examined with a cervical collar in place. Although a rigid collar provides some stability to the neck, residual motion can occur; however, this can be limited with the use of tape and sandbags. These devices should be gently removed while a second examiner applies a stabilizing force with mild in-line traction as the posterior elements are palpated. The hard collar is then replaced and appropriate imaging studies performed. When ventilatory support is required, the best method of intubation is controversial. ^, ^, ^, ^, It appears that gentle in-line traction with orotracheal or nasotracheal intubation is safe and does not lead to further neurologic injury. Pharmacologic treatment of patients with neurologic injuries is discussed later (“Pharmacologic Treatment of Spinal Cord Injury”).

Fig. 28.8, Proper transport of a child with a suspected cervical injury. (A) Because of the proportionally large head of a child, a standard backboard will result in cervical spine flexion. (B) A more appropriate transport backboard is one that includes a double mattress pad or a sunken headrest so that the head can fall back and provide a more normal lordotic position of the cervical spine.

Atlantooccipital Dislocation

This relatively rare injury usually occurs in MVAs and is associated with high mortality. Although atlantooccipital dislocation is often fatal, some children will survive this injury. There are numerous case reports of other children who have survived traumatic atlantooccipital dislocation; however, most survivors have neurologic complications. ^h

h References , , , , , , , , , , , , , .

Radiographic assessment of atlantooccipital dislocation can be difficult because radiographs obtained in the emergency department may appear normal. These injuries may be suspected from subtle plain film findings, such as an increased interspinous process distance. Although a number of radiographic measurements have been described, we prefer to use the Powers ratio when evaluating this injury ( Fig. 28.9 ). Historically, when atlantooccipital injury was strongly suspected in the absence of good radiographic evidence, the diagnosis was made with a lateral radiograph taken with mild traction carefully applied to the head; however, MRI has increasingly been used to identify this injury and other, more subtle injuries to the tectorial membrane. ^,

Fig. 28.9, Powers ratio. This ratio is determined by drawing a line from the posterior arch of the atlas (C) to the basion (B) and dividing this by the distance from the anterior arch of the atlas (A) to the opisthion (O) . A normal Powers ratio is less than 0.9. A ratio greater than 1.0 is diagnostic of atlantooccipital dislocation.

Treatment consists of halo application and stabilization and posterior fusion from the occiput to C1 or C2. ⁱ

i References , , , , , , .

Postoperatively, the patient is immobilized in a halo vest or halo cast ( Fig. 28.10 ). Although internal fixation in a young child is difficult, we have placed sutures or metal wire around the posterior elements of C1 and C2 and through the base of the skull. In older children, fixation with bicortical occipital screws and facet screws with contoured rods may provide stable fixation. Dural leak and venous sinus injury have been reported. Hedequist and co-workers reported a 100% fusion rate when pediatric fractures were treated with modern C-spine instrumentation systems often used for adults. Following instrumentation, halo immobilization is often required, especially in active children. The duration of immobilization should be 3 to 4 months. Patients with more stable injuries, such as tectorial membrane abnormalities noted on MRI scans, can be managed with immobilization without fusion. ^,

Fig. 28.10, Treatment of atlantooccipital dislocation. (A) Lateral radiograph demonstrating atlantooccipital dislocation. (B) Lateral radiograph obtained after halo application with reduction. (C) Lateral radiograph demonstrating fusion 4 months after injury and fusion from the occiput to C2.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here