An Upper and Middle Cervical Spine Posterior Arch Defect Leading to Myelopathy and a Thoracic Spine Posterior Arch Defect.

Background: Abnormalities of the posterior arches of the upper and middle cervical spine that can cause myelopathy are rare, and no reports of such defects at the thoracic spinal level have been published.

Case Description: A 29-year-old male patient reported right arm weakness and pain for 1 year. Magnetic resonance imaging of the cervical spine showed spinal canal stenosis at the C3-4 and C4-5 levels, as well as a posterior arch defect at the C2, 3, and 4 levels that was compressing the spinal cord. Three-dimensional cervical computed tomography (CT) showed that the spinous process and a piece of lamina were fused at each of the posterior C2, 3, and 4 levels, producing a free-floating bony structure. Spina bifida occulta was observed at C1. Osseous formation had failed between the lateral mass and spinous process at the C2 and C3 levels bilaterally, and the C4 level unilaterally. Three-dimensional thoracolumbar CT showed blocked vertebrae and spinous process fusion at T11 and T12. Osseous formation had failed between the lamina and spinous process at the T11 level unilaterally, and the T12 level bilaterally. The free-floating bony structure was successfully removed surgically.

Conclusions: A posterior arch defect of the upper and middle cervical spine leading to myelopathy combined with the same defect at the thoracic spine is a rare disease. If this congenital defect is detected at any spinal level, whole-spine CT can be helpful for accurately diagnosing the congenital anomaly.