PMC6369497_01
(a, b) Lateral plain radiographs of the cervical spine in flexion and extension at the age of 5 years. Multiple dysplastic vertebral bodies and atlantoaxial instability with os odontoideum are evident (white arrows).
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Although the stippled calcifications in the epiphysis had already disappeared, cervical radiography showed highly dysplastic vertebrae (Figure 1). At his first visit to our department, he showed no signs of myelopathy, and magnetic resonance imaging (MRI) showed no cervical spinal canal stenosis, although atlantoaxial instability due to os odontoideum was already apparent on radiography (Figure 1).
(a, b) Preoperative anterior-posterior and lateral plain radiographs of the cervical spine revealing multiple dysplastic vertebral bodies (white arrowheads). (c, d) Preoperative lateral plain radiographs of the cervical spine clearly demonstrating unstable atlantoaxial subluxation. (e) An anterior-posterior plain radiograph of the right hand revealing typical shortening of the distal phalanges (brachytelephalangy) of the thumb and middle and ring fingers. (f) Preoperative sagittal reconstructed computed tomography showing the segmented os odontoideum (white arrow). (g) Preoperative sagittal T2-weighted magnetic resonance (MR) images showing a severely compressed spinal cord at the C1/2 level with signs of myelomalacia inside the cord. A low-intensity retroodontoid mass is evident on the T2-weighted MR images. (h) Preoperative axial T2-weighted MR image at the C1/2 level revealing a severely compressed spinal cord. The white dotted lines in (g) indicate the level of (h).
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Cervical radiography revealed multiple dysplastic vertebral bodies (Figures 2(a) and 2(b)). Dynamic radiography revealed unstable atlantoaxial subluxation (Figures 2(c) and 2(d)). A plain radiograph of the right hand showed typical shortening of the distal phalanges (brachytelephalangy) of the thumb and middle and ring fingers (Figure 2(e)). Sagittal reconstruction computed tomography showed segmented os odontoideum (Figure 2(f)). MRI demonstrated severe spinal cord compression at the C1/2 level with a sign of myelomalacia inside the cord (Figures 2(g) and 2(h)). MRI also revealed a retroodontoid mass, which was thought to be a pseudotumor caused by upper cervical instability (Figures 2(g) and 2(h)).
(a, b) Lateral radiographs of the cervical spine in flexion and extension at 1 year after surgery demonstrating a stabilized O-C2 segment. (c) Sagittal reconstruction computed tomography taken at 1 year after surgery showing solid fusion between the grafted iliac bone and occipital bone (white arrow). (d) Sagittal T2-weighted magnetic resonance image taken at 1 year after surgery revealing a well-decompressed spinal cord with marked regression of the retroodontoid pseudotumor.
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Dynamic radiography revealed a stabilized O-C2 segment, although slight loosening of the pedicle screws at C2 was apparent (Figures 3(a) and 3(b)). Sagittal reconstruction computed tomography showed solid fusion between the grafted iliac bone and occipital bone (Figure 3(c)). MRI revealed a well-decompressed spinal cord with marked regression of the retroodontoid mass, which indicated that this mass was possibly a pseudotumor (Figure 3(d)).