Cervical Spine Trauma
- Anatomical differences exist in children predisposing them to different injury patterns than adults.
- Radiologic findings in children are frequently normal for age and a common cause of misinterpretation.
- MRI may be used to clear pediatric patient’s cervical spine (C-spine) when otherwise difficult.
- The majority of pediatric C-spine injuries may be treated with an orthotic or halo-vest, while operative treatment may be performed using modern screw-rod constructs.
Description:The age-related anatomical differences in children predispose younger children to injury at the upper cervical spine and adolescents in the subaxial cervical spine. Younger children have a larger head-to-body ratio making the fulcrum moment higher at the upper cervical spine. The inherent ligamentous laxity of children also predisposes them to upper cervical injuries given the difference in bony architecture and larger ligament attachments at occiput-C1 and C1-C2. Younger children have open synchondroses; the largest of these is at the dens. The dentocentral synchodrosis fuses at approximately age six years. Prior to that, younger children are at risk to sustain an injury at the dens thru this growth center. Odontoid fractures at this junction are the most common C-spine injury seen in children. Subaxial injuries are most often seen in adolescents once the anatomy has further developed.
Epidemiology:Cervical spine fractures represent less than 1% of all fractures seen in the emergency setting in children. The actual incidence is thought to be around 8 in 100,000 per year, however exact numbers are difficult to ascertain given reporting variation. The fracture pattern and cause of injury is different than in adults and is age-related, given the anatomical differences in children. (Jones, 2011) Motor vehicle accidents are the leading cause of fracture in all age groups, with falls being the second most common mechanism in younger children while sports injuries are the second most common mechanism in older children.
Clinical Findings:Children with a cervical spine fracture usually present with findings of neck pain and, occasionally, torticollis. Younger children may present with significant apprehension to neck movement and frequently will hold their heads with their hands in order to avoid any movement. Transportation of a child with a cervical spine injury deserves mention given the large head-to-body ratio. When younger children are lying flat, they are in a natural position of flexion given the large head size. This is due to the occiput being level with the rest of the body. Transport of children then must be done with either a specialized transport bed with an occipital recess or with blankets/padding underneath the body to raise the torso, which functionally allows the head to fall back and avoid flexing the cervical spine.(Copley, 1998) Increased neck stability, in addition to a collar on a backboard, can be done by taping the head with IV bags on the side of the head to prevent excessive movement in an apprehensive child. Initial physical exam should focus on Advanced Trauma Life Support (ATLS) protocol, a thorough secondary survey, as well as a detailed neurologic exam.
Imaging Studies:Standard radiographic analysis (AP, lateral, and open mouth view) is done with plain radiographs, which can be difficult to evaluate in children unless the normal variations in anatomy are understood. There are normal findings, which resemble fractures, subluxations, and ligamentous injuries.(Cattell, 1965) Pseudosubluxation of C2-C3 is a common finding in 25% of children and C3-C4 subluxation in 15% of children. The posterior line of Swischuk is a radiographic line that can help in this evaluation. This line is drawn from anterior aspect of posterior arch of C1 to anterior aspect of posterior arch of C3. The anterior aspect of posterior arch of C2 should be within 1-2 mm of this line, if so it is suggestive of pseudosubluxation. The dentocentral synchondrosis is seen in children up to six years of age and is frequently mistaken as a fracture. The atlantodens interval (ADI) in children is normal up to 5 mm. A loss of normal lordosis is a common finding as well as an increase in anterior soft tissue swelling (usually indicative of crying). The vertebral morphology in young children is frequently misinterpreted as a compression injury; however, the normal stages of development start with a smaller oval shaped body with development over time into a rectangular body. Morphologic variations of rounding of the anterior body as well as anterior wedging are seen in younger children.
Computed Tomography (CT) is used when evaluating a suspected bony or ligamentous injury. Routine use as a screening tool is not appropriate given the radiation dosing, however it has clear benefit when studying documented fractures.
Magnetic resonance imaging (MRI) is a superior study when evaluating ligamentous injuries or the spinal cord. (Flynn, 2002) In children who are obtunded and may not be cleared within 72 hours, MRI can be used as a screening tool in order to clear the neck and allow for collar removal for ease of nursing care in the ICU.
Injuries to the atlanto-occipital region, including atlanto-occiptal dissociation (AOD), are high energy injuries caused by sudden deceleration with the head moving forward on the cervical spine. Usually these are fatal injuries, however improvement in modern emergency medical services (EMS) systems with rapid stabilization and transport have allowed survival in some children. (Astur, 2013) Modern imaging techniques and a high degree of suspicion also account for improved diagnostic capabilities in these injuries which can often be difficult to ascertain given the challenges in assessing the craniovertebral junction with plain films. In patients with true AOD, an occiput to cervical fusion is required as halo immobilization is insufficient for these ligamentous injuries.
Odontoid fractures are the most common pediatric cervical spine fracture and usually seen in younger children. The mechanism is hyperflexion and is commonly a deceleration injury in an MVC. The fracture is through the dentocentral synchondrosis in children. Presentation is usually with significant apprehension and cervical pain and lateral radiographs demonstrate the anterior and flexed position of the dens. CT scanning is usually sufficient to clarify the injury although MRI may be used as well. Neurologic function is usually intact given the ample space available for the cord at that level. Treatment revolves around reduction and immobilization in a halo vest for six to eight weeks. Reduction is safely done under anesthesia with posterior translation and hyperextension under fluoroscopy and then immobilization in this position.
Os odontoideum, while thought to be a chronic unrecognized injury to C2, usually manifests itself in an acute setting with neck pain and occasional transient neurologic deficit. The appearance of an os can be mistaken for the dentocentral synchondrosis but can easily be differentiated by CT scanning. An os is a well rounded ossicle with defined borders above the level of the C1-C2 facets. This represents an unstable finding with resultant C1-C2 instability in both flexion and extension. Treatment of os odontoideum is surgical to avoid neurologic injury. Instrumented C1-C2 fusion is performed and usually entails iliac crest grafting with transarticular screws or a C1-C2 screw-rod construct. (Hedequist, 2014)
C1-C2 Rotatory Subluxation (traumatic torticollis)
A fixed C1-C2 subluxation may be the result of minor or major trauma. The patient presents with neck pain and spasm and holds the head rotated to one side and tilted. This is the result of pathologic rotation and subluxation of the atlanto-axial joints given the appearance of a “cock robin” position with restriction at any attempt at movement. The clinical appearance of the patient with a confirmatory CT scan is usually sufficient for the diagnosis. The Fielding-Hawkins classification exists and is related to the severity of displacement; however, treatment is usually mandated depending on the presentation and length of symptoms. High speed mechanisms with torticollis deserve further work-up with MRI to rule out a traumatic C1-C2 ligamentous injury. Low speed mechanisms need no further imaging and can be managed with a soft collar, NSAID’s, and antispasmodics for the first week. Patients who do not have an initial response after a week may need to be admitted and placed in halter traction or halo traction. Reduction is usually seen with an improvement in pain and return to a normal clinical appearance. Failure of traction to reduce the subluxation then requires positioning under anesthesia with halo vest placement or operative fusion via an instrumented C1-C2 fusion. (Glotzbecker, 2014)
Subaxial injuries are more common in adolescents and are usually due to an MVC or sports. (Murphy, 2014) Injuries include spinous process avulsion fractures, ligamentous injuries, facet fractures, compression fractures, and burst fractures. Treatment revolves around the injury pattern, stability potential, and neurologic deficit/cord compression. Stable injury patterns may be treated with cervical collar immobilization whereas unstable injuries require stabilization and fusion with segmental rigid instrumentation.
Complications:Complications are specific to the injury and treatment. Loss of reduction, malunion, or nonunion may occur with non-operative or operative treatment. Risks of infection, vascular injury, or neurological injury exist with operative treatment. Complications specific to halo vest immobilization include superficial pin site infection, brain abscess, skull fracture, and skin breakdown.
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