Addressing Stretch Myelopathy in Multilevel Cervical Kyphosis with Posterior Surgery Using Cervical Pedicle Screws

Abstract

Study DesignTechnique description and retrospective data analysis.PurposeTo describe the technique of cervical kyphosis correction with partial facetectomies and evaluate the outcome of single-stage posterior decompression and kyphosis correction in multilevel cervical myelopathy.Overview of LiteratureKyphosis correction in multilevel cervical myelopathy involves anterior and posterior surgery. With the advent of cervical pedicle screw-rod instrumentation, single-stage posterior kyphosis correction is feasible and can address stretch myelopathy by posterior shortening.MethodsNine patients underwent single-stage posterior decompression and kyphosis correction for multilevel cervical myelopathy using cervical pedicle screw instrumentation from March 2011 to February 2014 and were evaluated preoperatively and postoperatively with modified Japanese Orthopaedic Association (mJOA) scoring and computed tomography scans for radiological measurements. Kyphosis assessment was made with Ishihara curvature index and C2–C7 Cobb's angle. The linear length of the spinal canal and the actual spinal canal length were also evaluated. The average follow-up was 40.56 months (range, 20 to 53 months).ResultsThe average preoperative C2–7 Cobb's angle of 6.3° (1° to 12°) improved to 2° (10° to −9°). Ishihara index improved from −15.8% (−30.5% to −4.7%) to −3.66% (−14.5% to +12.6%). The actual spinal canal length decreased from 83.64 mm (range, 76.8 to 91.82 mm) to 82.68 mm (range, 75.85 to 90.78 mm). The preoperative mJOA score of 7.8 (range, 3 to 11) improved to 15.0 (range, 13 to 17).ConclusionsSingle-stage posterior decompression and kyphosis correction using cervical pedicle screws for multilevel cervical myelopathy may address stretch myelopathy, in addition to decompression in the transverse plane. However, cervical lordosis was not achieved with this method as predictably as by the anterior approach. The present study shows evidence of mild shortening of cervical spinal canal and a positive correlation between canal shortening and clinical improvement.

Influence of clinical and radiological parameters on the likelihood of neurological improvement after surgery for degenerative cervical myelopathy

“…Cervical kyphosis has been posited to stretch the spinal cord and lead to worsened myelopathy, irrespective of degree of cord compression. 23,37,[42][43][44][45] Although these studies proposed a correlation between sagittalplane parameters (including C2-7 Cobb angle and SVA) and response to surgery for DCM, our findings suggest that the specific degree of cervical kyphotic angulation is a better predictor of nonresponse after surgery. Importantly, postoperative sagittal parameters were equivalent between groups, including C2-7 Cobb angle and SVA, confirming that surgery provided adequate sagittal correction (when required) in both groups of patients.…”

Techniques of cervical pedicle screw insertion in lower cervical spine - A review

“…9,10 The superior strength has allowed surgeons to use CPS for cervical deformity correction as in thoraco-lumbar spine. 11,12 Therefore surgeons have always tried to find a reliable, reproducible and safe CPS insertion technique to expand the usage of CPS with minimal complications.…”