What to look for in a cervical x-ray, particularly the lateral view (Pa Lat), in a patient with trauma, pain, and limited neck movement?

Systematic Evaluation of Cervical Spine Lateral X-ray

When evaluating a lateral cervical x-ray in trauma, you must first ensure the film is technically adequate by confirming visualization from the craniocervical junction (occipito-atlantal articulation) to the cervicothoracic junction (C7-T1), as approximately 60% of cervical injuries occur at the cervicothoracic junction which is frequently not visualized. 1, 2

Critical Technical Adequacy Assessment

Before interpreting any findings, verify the film quality:

• Complete visualization required: Base of skull through C7-T1 junction must be visible 1, 2
• Cervicothoracic junction visibility: If C7-T1 is not visible, arm traction only succeeds in 7.7% of cases; a swimmer's lateral view is needed 1
• Adequate penetration: All vertebral bony structures and soft tissue relations must be visible 1

Critical pitfall: Up to 49% of lateral films fail to adequately visualize the cervicothoracic junction, and 50-90% of missed injuries result from poor quality films, inadequate views, or misinterpretation 1, 2

Systematic Evaluation Algorithm

1. Alignment Assessment

Evaluate four parallel lines on the lateral view:

• Anterior vertebral body line 2
• Posterior vertebral body line 2
• Spinolaminar line 2
• Posterior spinous process tips 2

Look for:

• Disruption in vertebral body alignment indicating fracture or dislocation 2
• Widened interspinous distances (>1.5 times adjacent level) suggesting posterior ligamentous injury 2
• Loss of normal cervical lordosis, which may indicate muscle spasm from injury 2

2. Bony Structure Evaluation

Examine each vertebra systematically:

• Vertebral body height and contour: Look for compression fractures, burst fractures, or obvious fracture lines 2
• Pedicles and laminae: Assess for fractures 2
• Spinous processes: Check for fractures or abnormal spacing 2
• Facet joints: Evaluate for subluxation or dislocation 2

3. Soft Tissue Assessment

Prevertebral soft tissue measurements are critical:

• At C3: >6 mm is abnormal (sensitivity 59% for cervical injury) 1
• At C6: >22 mm is abnormal (sensitivity only 5% for cervical injury) 1

Important caveat: These measurements become unreliable after intubation (tracheal or gastric) or while wearing a cervical collar 1, 2

Prevertebral soft tissue swelling has low sensitivity but high specificity, indicating ligamentous injury in 50% of cases when present 1, 2

Critical Limitations You Must Understand

The lateral view alone misses approximately 15% of cervical spine injuries even when technically adequate and interpreted by an expert (sensitivity 73.4-89.7%). 1, 2

Additional concerning statistics:

• 10-20% of missed injuries result from misinterpretation of suboptimal radiographs 1, 2
• A single lateral view has poor specificity of only 47-70% 1
• In the NEXUS study, adequate three-view series still missed 2.81% of all injuries 1

When Lateral X-ray is Insufficient

You should not rely on lateral x-ray alone in trauma evaluation. The ACR Appropriateness Criteria (2019) clearly state that CT has largely supplanted radiographs, with CT identifying three times more fractures than plain films 1

Mandatory Additional Imaging:

Three-view series minimum: 1, 2

• Cross-table lateral view
• Open-mouth odontoid view
• Anteroposterior view

Advance to CT when: 1, 2

• Any abnormal or ambiguous findings on x-ray
• High clinical suspicion despite normal x-ray
• Technically inadequate x-ray (cannot visualize C7-T1)
• Patient has altered mental status or is obtunded

Consider MRI when: 1, 2

• Neurological deficits present
• Suspected ligamentous injury
• CT negative but high clinical suspicion persists
• MRI identifies soft-tissue injuries in 5-24% of patients with negative CT 1

Practical Clinical Approach

In modern trauma care, if the patient meets NEXUS or Canadian C-Spine Rule criteria for imaging, proceed directly to CT rather than plain films, as CT is the gold standard for identifying cervical spine fractures. 1 Plain radiographs identify only about one-third of fractures visible on CT 1

The lateral cervical x-ray retains limited utility as a problem-solving tool when motion artifact degrades CT quality—a normal lateral radiograph in the area of patient motion may obviate repeat CT 1