J Korean Neurosurg Soc.  2021 Sep;64(5):837-842. 10.3340/jkns.2020.0293.

A Concomitant Occurrence of the Atlantoaxial Subluxation with Rare Vertebral Formation and Segmentation Defects

• Choi MK
• Kim SB
• Lee JH

• KMID: 2519711
• DOI: http://doi.org/10.3340/jkns.2020.0293

Abstract

An atlantoaxial subluxation from the unstable Os odontoideum by the failure of proper integrations between the embryological somites might be a commonly reported pathology. However, its suspicious origin or paralleled occurrence with other congenital anomalies of vertebral body might be a relatively rare phenomenon. The authors present two cases, who simply presented with clinical signs of prolonged, intractable cervicalgia without any neurological deficits, revealed this rare feature of C1–2 subluxation from the unstable, orthotropic type of Os odontoideum that coincide with congenitally fused cervical vertebral bodies between C2–3. Surprisingly, in one case, when traced from the lower cervical down to the thoracic-lumbar levels during the preoperative work-up process, was also compromised with multi-level butterfly vertebrae formations. Presented cases highlight the association of various congenital vertebrae anomalies and the rationale to fuse only affected joints.

Keyword

Atlanto-axial joint; Congenital anomaly; Os odontoideum; Joint instability

Figure

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  Fig. 1. The dynamic radiographies for the patient during the flexion (A) and extension (B) feature an unstable atlantoaxial dislocated condition. Note the complete reducibility for this condition during the patient’s self-flexional maneuver. The congenitally fused vertebrae between C2 and C3 with its prominent bony bridging formation between the spinous processes is also noted.

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  Fig. 2. The 3-dimensional reconstructed coronal (A) and sagittal (B) scans by the cervical spine computed tomography reveal an orthotopic type of Os odontoideum, margined and separated from the caudal C2 body by clean cortical bone. The fused, bony bridging phenomena are prominent along the both anterior and posterior vertebral body margins as well as between the lateral masses of the C2, C3, and C4.

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  Fig. 3. The 3-dimensional reconstructed coronal (A) and sagittal (B) computed tomography scans with the inclusion of the whole vertebral levels clearly depict the extension of the multilevel butterfly vertebrae formations from the lower cervical to thoracic-lumbar junctional levels with the few intervening normal shaped vertebrae.

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  Fig. 4. The dynamic radiographs during the neck flexion (A) and extension (B) taken 9 months’ post-operative period after the reduction with allograft on-layed feature a full radiological restoration of the inherent atlantoaxial dislocated instability.

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  Fig. 5. The plain radiographs, lateral view of the case 2 showed the AAD feature with slightly retropulsed os odontoideum over C2 body proper (black arrow), which was untowardly stabilized by cortical rim connection with ventral portion of the C3 vertebra (white arrow). Note the decreased anterior-posterior diameter of the vertebral bodies at the fused C2, C3, as well as C4 levels as compared with the lower subaxial cervical bodies.

Reference

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