X-ray Skills 2:
Cervical Spine X-ray Interpretation
A lateral cervical spine x-ray is obtained as an initial
trauma series
x-ray. Unstable cervical spine injuries will be detected about 80% of
the time
with this single view. Some unstable injuries are not seen with routine
x-rays,
so spine immobilization is necessary whenever significant force could
have
caused an injury and maintained until complete evaluation after initial
resuscitation. Complete spine immobilization is difficult to obtain and
maintain
during patient movement from cart to car, etc. The lateral cervical
spine x-ray is
useful only because it will detect certain ominous injuries early, with
resulting
concern for rigorous immobilization by the team and involvement of a
neurosurgeon
at an early stage before progression of the injury can occur.
What to look for on the lateral cervical spine x-ray:
- The prevertebral space at the level of C-3 should be less than 5 mm in adults. PEDS: This space is difficult to interpret in children because it can vary widely with swallowing, breathing, and crying. The prevertebral space in children should not exceed two-thirds of the width of the body of C-2. The prevertebral space below the larynx should not exceed the width of the body of C-6.
- The anterior alignment of the vertebral bodies. The vertebral bodies should form a smooth curve anteriorly; however, degenerative changes can make interpretation difficult. Look for bony flecks off of the superior aspects of the vertebral bodies that signify ligamentous injury. A bone chip off of the inferior aspect of a vertebral body is called a tear-drop sign and is ominous for instability and cord injury. Also, carefully note the alignment of the odontoid process with the body of C-2. Fractures of the shaft of the odontoid above the body of C-2 are called Type I odontoid fractures and are usually stable. Fractures at the base of the process (Type II) are unstable and ominous as are fractures involving both the odontoid process and the body of C-2 (Type III).
- The predental space. This space should not exceed 3 mm in adults or (PEDS) 4 mm in children. Increased distance here signifies disruption of the transverse ligament that holds the odontoid process against C-1 and may accompany fractures of C-1. This is an unstable and ominous injury.
- The posterior alignment of the vertebral bodies and intervertebral disk spaces. Subluxation of a vertebral body, bony fragments, and intervertebral disks into the spinal canal are ominous signs. A narrowed disk space can be a clue that extrusion of a disk into the spinal canal has occurred; C-7 can be subluxed on T-1, so be sure that you can see this junction. Obtain a swimmer’s view x-ray if this area is not seen on a standard lateral x-ray.
- The arch of C-1 and the atlanto-occipital alignment. Although it may be normally incomplete, the arch of C-1 should be carefully examined because it can be a clue to the presence of a burst fracture (Jefferson’s fracture) caused by a blow to the top of the head. This is an unstable injury. Atlanto-occipital disruption is almost always immediately fatal, but a rare case will present still alive. Look for alignment of the clivus with the odontoid process.
- The pedicles, laminae, and lateral masses. The pedicles connect the lateral masses to the vertebral bodies; the lamina connect the lateral masses to the spinous processes. Fractures through these structures can cause instability. The hangman’s fracture is a fracture through these structures of the C-2 vertebral body. The lateral masses of the vertebral bodies articulate with each other at facet joints. If the disk and ligaments between two vertebral bodies are disrupted, the bodies can rotate on each other to an abnormal degree resulting in dislocation of one or both facet joints resulting in “locked facets.” The alignment of the lateral masses should be consistent on x-ray.
- The spinolaminal line. Disruption of the spinolaminal line is an important indicator of subluxation that might not otherwise be apparent. Always draw a line from the posterior limit of the spinal canal at C-1 to the same point of C-3. The same point of C-2 should be within 1 mm of this line. If not, presume an unstable injury of the odontoid or pedicle fractures of C-2.
- Spinal stenosis. The width of the spinal canal on x-ray is normally 13 mm. Patients with spinal stenosis because of degenerative disease are at risk of spinalcord injury with minor trauma.
- Spinous process angulation. Angulation of the spinous processes of 11 or more degrees signifies fracture or ligamentous disruption.
Examine C-spine X-rays
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Check
the predental space:
Check the posterior alignment of the vertebral bodies Check the width of the spinal canal (between spinolaminar line and posterior vertebral lines) Check the alignment of the spinolaminar line Check the first 3 points of the spinolaminar line for straightness Check the spinous processes for fracture |
Assess
airway for foreign bodies and obstruction Check for prevertebral swelling
Look at rami of the mandible Check for uniformity of:
Look at junction between C7 and T1. |