Correlation between cervical curvature and spinal cord shift, surgical outcome after expansive open-door laminoplasty

English Keywords:Laminoplasty  Cervical curvature  Kyphosis  Spinal cord shift  Outcome

English Abstract:

  【Abstract】 Objectives: To observe the spinal cord shift and surgical outcome of different types of cervical curvature after expansive open-door laminoplasty for cervical myelopathy, and to investigate the relationship between cervical curvature and spinal cord shift. Methods: 63 cases of cervical myelopathy undergoing traditional expansive open-door laminoplasty between January 2005 and December 2011 were reviewed retrospectively, the pathogenesis included cervical spondylotic myelopathy(26 cases), ossification of posterior longitudinal ligament(OPLL, 20 cases) and developmental cervical spinal stenosis(17 cases). Traditional expansive open-door laminoplasty was performed because of multisegmental disc disease, multilevel OPLL or developmental cervical stenosis. All cases were divided into three groups according to the cervical curvature: the kyphosis group(n=16), the straight group(n=18) and the normal alignment group(n=29). The posterior shift of center of spinal cord(PCS) at each level of laminoplasty(C3-C7) was measured and calculated through the midsagittal images of MRI T2-weighted before and after surgery. Statistic analysis was performed to analyze the difference of PCS at each level(C3-C7) among three groups. The neurofunction for each patient was estimated by using the Japanese Orthopedic Association(JOA) score before surgery and at final follow-up, and the JOA recovery rate was calculated. Statistic analysis was performed to analyze the difference of the JOA recovery rate at final follow-up among three groups. Results: There was no statistical difference in the age, sex ratio, duration of symptoms, entity, follow-up time or the preoperative JOA score(P>0.05). Posterior migration of spinal cord was observed in all three groups, and there was no significant difference with respect to the mean PCS at C3-C7 level among three groups(P>0.05). The mean follow-up was 47±24(range 15-90) months, and the mean JOA recovery rate at final follow-up of each group was 59.81%, 69.25% and 54.44% respectively, which showed no statistical difference(P>0.05). No linear correlation was found between the JOA recovery rate at latest follow-up and the postoperative PCS at C5 level(r=0.110, P=0.390). Conclusions: The spinal cord shift can be observed in patients regardless of different types of preoperative cervical curvature, and all showed good neurofunctional recovery.