PMC6698508_01
A) Computed tomography showed C2-7 ossification of the posterior longitudinal ligament. The most stenotic level was at C4-5. Furthermore, continuous ossification of the anterior longitudinal ligament was observed at C7-L3 and continuous ossification of the supra-spinous process ligament at T4-L1; C7-L3 was fused and had no motion segment. B) Axial CT slice of C4-5. C) Magnetic resonance imaging revealed spinal cord compression at C4-7.
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Magnetic resonance imaging revealed stenosis from C3/4 to C6/7 (Fig. 1).
Preoperatively, the O-C2 angles were 16  (neutral), 6  (flexion), and 31  (extension); the C2-7 angles were 28  (neutral), 15  (flexion), and 33  (extension). Postoperatively, the O-C2 angles were 16  (neutral), -2  (flexion), and 24  (extension). The C2-7 angle was 28 , which showed no change, and the pharyngeal tilt angle (PTA) changed from 84  to 94 .. The PTA was described as the angle between the McGregor's line and the line that links the center of the C2 pedicle and the center of the vertebral body at the apex of the cervical sagittal curvature.
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The C2-7 sagittal vertical axis (SVA) was 32.5 mm, and the pharyngeal tilt angle (PTA) was 84  (Fig. 2). The C2-7 SVA was 36 mm, and the PTA was 94  (Fig. 2).
A) Barium esophagography revealed an occlusion at the C5/6 level osteophyte (arrow).. B, C) The barium was still clogged up on esophagography despite C5/6 anterior osteophyte removal. The hyoid (black circle) moved vertically but not anteriorly because of the weakness of the laryngeal muscle and difficulty in moving the neck forward.
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The hyoid moved vertically but not anteriorly because of the weakness of the laryngeal muscle and difficulty in moving the neck forward (Fig. 3).