What is spondylolysis in a cervical spine X-ray (X-ray)?

What is Spondylolysis in Cervical Spine X-ray

Cervical spondylolysis is a rare congenital or developmental defect appearing as a well-corticated cleft in the pars interarticularis (the region between the superior and inferior articular facets) of a cervical vertebra, most commonly at C6 or C4 levels. 1, 2

Radiographic Characteristics

The key imaging features that distinguish cervical spondylolysis from acute traumatic fractures include:

• Well-marginated, corticated cleft between the superior and inferior articular facets, indicating a chronic rather than acute process 1, 2
• Triangular "bow tie" configuration of the pillar fragments on either side of the defect 1, 2
• Posterior displacement of the dorsal triangular pillar fragment 1
• Ipsilateral pedicle hypoplasia at the affected level 1, 2
• Spina bifida frequently present at the involved vertebral level 1, 2
• Compensatory hypertrophy or hypoplasia of adjacent articular pillars above and/or below the defect 1, 2

Critical Differentiation

The most important clinical distinction is separating cervical spondylolysis from acute traumatic hangman's fracture, which has completely different management implications. 3, 2

• Traumatic fractures show sharp, non-corticated margins without the chronic remodeling changes seen in spondylolysis 1, 2
• Spondylolysis demonstrates dysplastic changes and associated congenital anomalies that are absent in acute trauma 1

Imaging Approach

• Plain radiographs (AP and lateral views) are the initial screening tool, though the diagnosis is frequently missed initially 1
• CT with multiplanar reformats is the most accurate modality for demonstrating the bony defect and characteristic features 1
• MRI may be needed if there is concern for instability, neurological compromise, or to evaluate soft tissue structures 3, 1
• Flexion-extension radiographs are essential to assess for C2/3 instability, which determines whether surgical intervention is needed 3

Clinical Significance

• Most patients with cervical spondylolysis are asymptomatic or have mild neck pain that responds to conservative management 2
• Progressive instability at the adjacent segment (typically C2/3) is the primary concern requiring surgical intervention 3
• Neurological deficits referable to the unstable segment warrant surgical stabilization 3, 2
• Conservative treatment with activity modification is successful in the vast majority of cases 2

Common Pitfalls

• Misdiagnosis as acute fracture occurred in 9 of 12 patients in one series, potentially leading to inappropriate immobilization or surgical intervention 1
• Failure to assess for instability with flexion-extension views can miss the primary indication for surgery 3
• Overlooking associated dysplastic features (spina bifida, pedicle hypoplasia) that confirm the chronic congenital nature of the lesion 1, 2