Traumatic high-grade spondylolisthesis at C7-T1 with no neurological deficits: Case series, literature review, and biomechanical implications.

Traumatic high-grade spondylolisthesis in subaxial cervical spine is frequently associated with acute spinal cord injury and quadriparesis. There have been rare cases where such pathology demonstrates minimal to no neurological deficits. Assessment of the underlying biomechanics may provide insight into the mechanism of injury and associated neurological preservation. Patient 1 is a 63-year-old female presenting after a motor vehicle collision with significant right arm pain without neurological deficits. Imaging demonstrated C7/T1 spondyloptosis, associated with a locked facet on the left at C6/7 and a locked facet on the right at C7/T1, with a fracture of the left C7 pedicle and right C7 lamina. Patient 2 is a 60-year-old male presenting after a bicycle collision with transient bilateral upper extremity paresthesias without neurological deficits. Imaging demonstrated C7/T1 spondyloptosis, with fractures of bilateral C7 pedicles, C7/T1 facets, and C7 lamina. Patient 3 is a 36-year-old male presenting after a motor vehicle collision with diffuse tingling sensation throughout all extremities. His neurological examination was nonfocal. Imaging demonstrated a grade 4 spondylolithesis at C7/T1, associated with bilateral C7/T1 locked facets. From literature, most cases were noted to be dislocations resulting from fractures of the posterior elements. A minority of cases has been found to involve facet dislocations without fractures. Further biomechanical studies are needed to understand the underlying mechanisms.