| Objective： Clinical studies have indicated that posterior cervicallaminectomy is one of the effective methods for treating multi-section ofcervical spondylotic myelopathy (CSM), ossification of cervical posteriorlongitudinal ligament (OPLL) and cervical spinal canal stenosis of spinal cordcompression caused by cervical stenosis. The indirect decompressive effectdepends on the range of posterior cervical laminectomy but also thephysiological lordosis of cervical vertebrae. The shift extent of postoperativecervical cord related to the lordosis had been shown in some studies.According to the bowstring principle, physiological cervical lordosis causingshift of cervical cord to avoid compressing from osteophyma and slipped diskbetween the vertebrae and spinal cord after posterior cervical laminectomy.But the shift of cervical cord will not significantly be improved in the patientswith cervical kyphosis. Thus the cervical kyphosis is a relativecontraindication for posterior cervical laminectomy. At present, the correlationbetween eikonic parameters in posterior cervical laminectomy and spinalcord shift have been in debate and posterior cervical laminectomy lateral massscrew internal fixation was used in few study. Lateral mass screw internalfixation was induced to reduce the effect of cervical curvature caused byposterior cervical laminectomy, and the lateral mass screw internal fixationcould orthopaedic cervical kyphosis. The slight shift of spinal cord aftercervical surgery have poor efficiency but the large degree in spinal shift couldlead to heavy axial symptoms and C5nerve root palsy. Based on prior studies,further investigation was took to search the correlation between the shift ofspinal cord and cervical curvature in patients pre-and post operation.Methods：17patients (male:11cases) with CSM or OPLL who received the operation of posterior cervical laminectomy lateral mass screw internalfixation were enrolled continuously from March2008to October2011inspinal orthopedic of the Third Hospital of Hebei Medical University. Therange of age in patients was47years to74years and the pathogenetic durationafter onset was6to36months. Patients with C3-C6, C4-C7, C3-C7cervicalsegments involved was seen in7cases,6cases,4cases respectively andcorresponding segments were decompressed. Cervical X-ray films, CT andMRI were checked pre-operation. After3months postoperatively, cervicalX-ray films and MRI were reviewed. The eikonic records above werecollected to measure the Cervical Curvature Index (CCI) and cervical Cobbangle pre-and post operative respectively. The Average Clearance of Spinalcord (ACS) was only measured on the postoperative MRI. All of the data weremeasured three times to obtain the mean. The correlation between the CCI,Cobb angle pre-and post operation and postoperative ACS was evaluatedpreliminarily depending on the scatter plot. Comparison and correlationanalysis of measurement data tested in paired t-test. Statistics analyses wereperformed with the SPSS19.0package for Windows. We considered P＞α(α=0.05) as statistically significant.Results：The preoperative CCI was10.78%±10.28%, postoperative CCIwas11.73%±9.96%,0.95%±6.28%changed of CCI in postoperative thanthat in preoperative, the preoperative Cobb angle12.19°±9.72°,postoperative Cobb angle was10.85°±11.70°,-1.34°±4.38°changed ofCobb angle in postoperative than that in preoperative, postoperative ACS was2.35mm±0.88mm. The linear correlation between CCI, Cobb angle pre-andpost operation and postoperative ACS had be shown by the scatter plot ofthem and the paired t-test analysis, P<0.05. All operation for the patients weresuccessful,1patient had wound fat liquefaction and han taken out stitches13days later through strengthen the wound care;5patients had neck axialsymptom postoperative and had recovered gradually through receivedphysiotherapy and symptomatic treatment; one cases of patients hadpostoperative C5nerve root palsy and had recovered gradually about6weeks later through received physiotherapy and functional exercise. Thepostoperative ACS of the patient who had C5nerve root palsy was3.89,significantly higher than the average.Conclusion：Based on the preliminary studies, operation style waslimited in posterior cervical laminectomy lateral mass screw internal fixationto reduce the effect of cervical curvature caused by posterior cervicallaminectomy simply, and the lateral mass screw internal fixation couldorthopaedic cervical kyphosis. The shift of cervical cord strongly correlatedwith cervical curvature pre-and post operation. The larger the angle ofCervical lordosis was, the farther the shift of spinal cord changed. Then theextent of spinal cord shift would be prejudged to evaluate the therapeuticeffect. Cervical lordosis closed to physiological curvature should be recoveredfor patients with cacoethic cervical curvature in operation. Especially forpatients with cervical lordosis in lager extent, the enlargement of cervicallordosis should be avoided. |
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