PMC4533371_01
A: Cervical spine x-ray obrtained three years bofore her first visit to us shows C2 spondylolysis (arrow) and kyphotic deformity of the whole spine. B: The flexion and extension x-ray at this point shows the gap in the C2 pars defect (arrow) widens from 0 mm in extension to 4 mm in flexion. C: The flexion and extension x-ray at her first visit to us shows the gap of C2 pars defect (arrow) widened 6 mm in flexion, which suggests progressive cervical spinal instability.
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F1
Repeat lateral cervical spine x-ray demonstrated C2 spondylolysis (Fig. 1A, arrow) and hyperlordosis at C1/2 segment as well as an angular deformity at the C2/3 disc space. Repeat flexion and extension x-ray showed the gap in the C2 spondylolysis widened from 0 mm in extension to 4 mm in flexion (Fig. 1B, arrow). The flexion and extension x-ray showed C2 spondylolysis with a gap that widened from 0 mm in extension to 6 mm in flexion (Fig. 1C). C2 pars interarticularis had widened over time compared to the imaging obtained 3 years beforehand (Fig. 1B), suggestive of progressive cervical spinal instability.
Sagittal cervical spine computed tomography (paramedian plane on the left side; A-C, paramedian plane on the right side; D-F, midline plane; G) reveals a deformity of the odontoid with posterior angulation of the tip, a partial absence of the posterior arch C1 and a fusion of the posterior arch of C2 and C3 with a bilateral spondylolysis (arrow) of the C2 pars interarticularis. Cervical spine magnetic resonance imaging (H) demonstrates no evidence of spinal cord compression, ligament injury, hematoma and soft tissue injury, which help us rule out hangman fracture.
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F2
CT sagittal image (Fig. 2A-G) revealed a deformity of the odontoid with posterior angulation of the tip, a partial absence of the posterior arch of C1, and a fusion of the posterior arch of C2 and C3 with a bilateral C2 spondylolysis. CT axial image (Fig. 3A-J) demonstrated well-corticated clefts on both sides of the spondylolytic defects. Cervical spine magnetic resonance imaging (MRI) demonstrated no evidence of spinal cord compression, spinal cord signal change, ligament injury, disc disruption, soft tissue injury, or hematoma (Fig. 2H).
Axial images of cervical spine computed tomography (A-J) show a partial absence of the posterior arch of C1 (A-D) and triangular pillar fragments with well-corticated and well-defined margins on both sides of the spondylolytic defects of C2 (E-J). These imaging characteristics indicate congenital dysgenesis of pars interarticularis, which is completely distinct from acute hangman's fracture.
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F3
CT sagittal image (Fig. 2A-G) revealed a deformity of the odontoid with posterior angulation of the tip, a partial absence of the posterior arch of C1, and a fusion of the posterior arch of C2 and C3 with a bilateral C2 spondylolysis. CT axial image (Fig. 3A-J) demonstrated well-corticated clefts on both sides of the spondylolytic defects. Cervical spine magnetic resonance imaging (MRI) demonstrated no evidence of spinal cord compression, spinal cord signal change, ligament injury, disc disruption, soft tissue injury, or hematoma (Fig. 2H).
Cervical spine x-ray at 1-year postoperative follow-up revealed rigid fixation and excellent spinal alignment.
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F4
At 1-year follow-up, the patient was completely neurologically intact and cervical spine x-rays showed rigid fixation and excellent spine alignment (Fig. 4).