A late neurological complication following posterior correction surgery of severe cervical kyphosis |
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Authors: | Yoshihiro Hojo Manabu Ito Kuniyoshi Abumi Yoshihisa Kotani Hideki Sudo Masahiko Takahata Akio Minami |
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Institution: | (1) Department of Orthopaedic Surgery, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan; |
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Abstract: | Though a possible cause of late neurological deficits after posterior cervical reconstruction surgery was reported to be an
iatrogenic foraminal stenosis caused not by implant malposition but probably by posterior shift of the lateral mass induced
by tightening screws and plates, its clinical features and pathomechanisms remain unclear. The aim of this retrospective clinical
review was to investigate the clinical features of these neurological complications and to analyze the pathomechanisms by
reviewing pre- and post-operative imaging studies. Among 227 patients who underwent cervical stabilization using cervical
pedicle screws (CPSs), six patients who underwent correction of cervical kyphosis showed postoperative late neurological complications
without any malposition of CPS (ND group). The clinical courses of the patients with deficits were reviewed from the medical
records. Radiographic assessment of the sagittal alignment was conducted using lateral radiographs. The diameter of the neural
foramen was measured on preoperative CT images. These results were compared with the other 14 patients who underwent correction
of cervical kyphosis without late postoperative neurological complications (non-ND group). The six patients in the ND group
showed no deficits in the immediate postoperative periods, but unilateral muscle weakness of the deltoid and biceps brachii
occurred at 2.8 days postoperatively on average. Preoperative sagittal alignment of fusion area showed significant kyphosis
in the ND group. The average of kyphosis correction in the ND was 17.6° per fused segment (range 9.7°–35.0°), and 4.5° (range
1.3°–10.0°) in the non-ND group. A statistically significant difference was observed in the degree of preoperative kyphosis
and the correction angles at C4–5 between the two groups. The diameter of the C4–5 foramen on the side of deficits was significantly
smaller than that of the opposite side in the ND group. Late postoperative neurological complications after correction of
cervical kyphosis were highly associated with a large amount of kyphosis correction, which may lead foraminal stenosis and
enhance posterior drift of the spinal cord. These factors may lead to both compression and traction of the nerves, which eventually
cause late neurological deficits. To avoid such complications, excessive kyphosis correction should not be performed during
posterior surgery to avoid significant posterior shift of the spinal cord and prophylactic foraminotomies are recommended
if narrow neuroforamina were evident on preoperative CT images. Regardless of revision decompression or observation, the majority
of this late neurological complication showed complete recovery over time. |
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Keywords: | Cervical kyphosis Spinal reconstruction Pedicle screw fixation Neurological complication Foraminal stenosis |
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