Minimally Invasive Laminoplasty For Cervical Spondylotic Myelopathy Using Microendoscopy

Background and Objective The incidence of cervical spondylotic myelopathy is 12%-30% in cervical spondylosis.The incidence of cervical spondylotic myelopathy increases with age.There are a variety of methods for the treatment of cervical spondylotic myelopathy,and each has its advantages and disadvantages.Therefore,there is still controversy about the choice of surgical methods.Anterior cervical surgery is effective in the treatment of single segment lesions.But anterior cervical fixation may cause intervertebral disc degeneration in adjacent segments.Posterior cervical surgery methods including laminectomy and laminoplasty.Many scholars hold that multisegmental cervical spondylotic myelopathy should be treated with posterior cervical surgery,and better nerve recovery can be achieved.Posterior cervical surgery damage the posterior anatomical structure of cervical spine too much.And it results to many surgical complications,such as axonal symptoms,C5 nerve root paralysis,and so on.In recent years,scholars at home and abroad have been exploring a method for the surgical of cervical spondylotic myelopathy to reduce surgical complications.In recent years,we have invented a cervical microendoscopic laminoplasty,which could achieve better decompression under the premise of preserving most of the normal osteo-ligamentous anatomy of the cervical spine,and it increase the stability of cervical vertebra after operation and effectively reduc the incidence of complications.The aim of this study was to explore the indications feasibility,clinical outcome and safety of minimally invasive laminoplasty technique for cervical spondylotic myelopathy(CSM),to analysis the related factors of the operation and provide valuable reference for the selection of surgical methods for CSM.Experimental method From January 2011 to December 2013,51 patients with CSM treated by this technique in our hospital were reviewed in this study.All these patients were followed up at least 9 months.There were 28 males and 23 females with a mean age of 58 years(range 41-76 years).All patients were found to have cervical disc herniation with spinal cord compression.Among these patients,2 segments(C5-6),3 segments(C3-5/C4-6),4 segments(C3-6)and 5 segments(C3-7)laminoplasty performed in 5,7,22 and 17 cases respectively.Therapy effect and axial symptom were evaluated according to Japanese Orthopedic Association(JOA)scores and visual analogue scales(VAS)respectively.Cervical curvature index(CCI)and range of motion(ROM)were judged by X-ray.The sagittal diameter of cervical spine,canal enlargement and bony healing were judged by CT scans.Spinal cord signal intensity changes and spinal cord decompression status judged by MRI.Statistical analysis of JOA score,VAS score,CCI and ROM were performed by paired design t test.Results The mean operative time was(115±21.9)min,ranging 58-139 min.The mean blood loss was(227+73.2)ml,ranging 110-380 ml.The follow-up time ranged 9-36 months with an average of 20±5.91 months.The mean JOA scores had improved from 8.02±1.69 pre-operatively to 13.02±1.48 post-operatively.The results were excellent in 17 cases,good in 28 and fair in 4.The VAS scores of axial pain significantly improved to 2.22±0.90 at the final follow-up compared with 4.96±1.39 preoperatively.Axial symptom were excellent in 18 cases,good in 21 and fair in 12.Pre-operative was 15.40%±4.50% and postoperative was 15.09%±4.87%,there was no significant difference.ROM of pre-operative was 40.98° ±8.27° and postoperative was 38.88° ±9.53°,and there was no significant difference.The sagittal diameter of the spinal canal increased 1.3-3.2mm postoperatively with an average of(2.320±0.42)mm.A total of 204 vertebral lamina were bilaterally slotted and fixed.146 lamina were observed bone healing at the last follow-up.The bone healing rate was 71.6%.Complications such as upper limb motion dysfunction occurred in 1 case muscle strength restored after treatment of methylprednisolone sodium succinate,and little screw looseness in occurred 1 case,and no special treatment was given.Conclusion CMEL is a new surgical approach which causes less damage to the spinous process-ligament complex and the deep extensor muscles,and the procedure can be used for CSM effectively and safely.