Differential Analysis Of The Spinal Cord Shift After Laminoplasty With Upper Extension To The C2 Segment And Conventional Surgery Of The C3-7 Segments

Objective:This study aimed to clarify the differences in distances of spinal cordshift between laminoplasty with extension to the C2 segment and conventional surgery of the C3-7segments and to better understand laminoplasty.Methods:The median sagittal MRI T2 scan images for the patients before and after surgery were used for the data collection.Including the anterior subarachnoid spaces(ASS),spinal cord diameters,(SCD),posterior subarachnoid spaces(PSS),and dural sac diameters(DSD),were measured for the two planes of the midpoint of the posterior margin of vertebral body and intervertebral disc in the C1-C7.The distance of spinal cord shiftin a single plane is represented by the difference in the sum of the ASS and the SCD before and after surgery.The overall backward shift distance of the spinal cord is the average of the backward shift distance for each measurement plane of the C1-7segments.The overall and each segment posterior shift distances of spinal cordwere compared for the C2-7 group and C3-7 group.All of the planes were also classified as segments with compression or without compression,and the difference in the backward shift was compared.Results:There were significant spinal cord shift after surgery in both groups,while there was no statistically significant difference in the overall backward shift distance between the two groups.The backward shift distances of the spinal cord C1,C2,and C2/3segments and the segment with the largest backward shift distance were significantly different;the comparison of the segments with and without compression in all cases showed that the spinal cord shift of the segments under compression was larger than noncompression.Conclusion:Surgery with upper extension to the C2 segment did not increase the overall backward shift distance of the spinal cord for a better decompression effect;instead,a better effect was achieved by the effective decompression of local compressed segments,thus obtaining an effective expansion and shift of the spinal cord.