Fig. 1

Initial computed tomography: scout view (A) showing the C4–C5 complete dislocation with spondyloptosis of C4 (arrow) and severe local kyphosis resulting in flexion of the head on the anterior chest wall with evident sinuosity of the respiratory tract (arrowheads, showing angulation of the trachea). Note the close proximity between the anterior aspect of the mandible and the sternum. Reformatted sagittal images on the midline (B) and at the level of the right facet joints (C) show complete dislocation at the C4–C5 level, with spondyloptosis of the C4 vertebral body anteriorly to C5 (arrow B) and complete anterior translation of the inferior C4 facet joint “locked” at the anterior aspect of the superior C5 facet (arrow in C). Sclerosis of the adjacent vertebral angles (arrowhead in B) and periarticular calcifications posteriorly (arrowhead in C) indicate the dislocation as established for several weeks