Segmentation failure of the posterior elements at the cervical spine and cervicothoracic junction: report of three cases.

Purpose: Vertebral segmentation and fusion failures are quite common and often occur as incidental findings. These anatomical variants may be associated with deformity and lead to pain and other neurological signs. They are less frequent in the cervical spine. We report three cases of rare posterior arch segmentation failure at the cervical spine and cervicothoracic junction, with an interesting pattern of laminar arrangement.

Methods: The clinical and radiological findings of three patients with unusual anatomical variants of the posterior elements of the subaxial cervical spine and cervicothoracic junction are reported.

Results: We found various association of scoliosis, partial butterfly vertebra, absent pedicle, transverse process and lateral mass anomalies. Interestingly, we report two different and unusual laminar morphologies.

Conclusion: Congenital morphological disorders may occur at the lower cervical spine and cervicothoracic junction, and they can involve the vertebral body as well as the posterior arch. We reported three cases of uncommon malformations, with a unique Y- and S-shaped laminar pattern.