PMC5203869_01
Preoperative images. Preoperative MRI (a, b, and c) and CT myelogram (d, e, and f) showed mixed-type OPLL compressing spinal cord, especially at C3-4 (OPLL canal occupying ratio: 50%). MRI showed no obvious cord signal change and cord enlargement (a, b, and c). The anterior-posterior diameters of right and left C4/5 foramen were 3.8 mm and 3.5 mm, respectively (f).
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Her OPLL was mixed type from C2 vertebral body (VB) level down to C6 VB level, discontinuation at C3/4 with most cord compression, OPLL spinal canal occupancy ratio of 50%, and no C4/5 foraminal stenosis observed (Figure 1).
MRI and CT images taken at onset of C5 palsy. MRI (a, b) and CT imaging (c, d) obtained immediately after onset of C5 palsy showed the intramedullary T2 high signal change and spinal cord enlargement from C2 vertebral body level to C4 vertebral body level (a, b) without any graft dislodgement or implant malposition (c, d).
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Imaging studies on the same day of left-arm symptoms onset demonstrated T2 high intramedullary signal change and spinal cord enlargement from C2 VB level down to C4 VB level not evident prior to surgery on cervical MRI and no graft and implant malposition on CT images (Figure 2).
Intraoperative spinal cord monitoring. Although there was no worsening of left deltoid and left AH CMAPs during the 1st (a, b) and the 2nd (c, d), each operation was observed and low amplitude of left deltoid (c) and preserved amplitude of left AH CMAPs (d) in the 2nd operation compared to the 1st operation (a, b) were recorded, which means segmental C5 palsy occurred after the postoperative period of the 1st operation.
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The left deltoid and bicep muscles demonstrated reduced amplitude throughout the second round of surgery and the amplitude and latency of the rest of the muscles in MEP and SEP were the same compared with the first round of surgery in the intraoperative spinal cord monitoring (Figure 3).
MRI taken three weeks after the second round of surgery. The spinal cord enlargement and intramedullary high intensity change disappear on T1 (a) and T2 (b) weighed MRI.
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T2 high intramedullary signal change disappeared on MRI taken three weeks after the second round of surgery (Figure 4).