Differential Analysis of the Spinal Cord Shift After Laminoplasty With Upper Extension to the C2 Segment and Conventional Surgery of the C3-C7 Segments.

Study Design: A retrospective controlled study. Objective: To clarify the differences of spinal cord shift between laminoplasty with extension to the C2 segment and conventional surgery of the C3-C7 segments. Summary of Background Data: For patients of spinal cord compression at C2/C3 or C2, it is difficult to achieve decompression involving only the C3-C7 segments. Therefore, a laminoplasty with upper extension to C2 is needed. Nevertheless, there is not yet a definitive conclusion regarding whether laminoplasty with extension to C2 can achieve a better spinal cord shift than an extension of the C3-C7 segments. Materials and Methods: Preoperative and final follow-up Japanese Orthopedic Association scores were recorded. MRI T2 patient images before and after surgery were used for data collection. The anterior subarachnoid spaces, spinal cord diameters, posterior subarachnoid spaces, and dural sac diameters were measured. The distance of spinal cord shift in a single plane was represented by the differences in the sum of the anterior subarachnoid spaces and the spinal cord diameters before and after surgery. The overall distances and distances of each segment backward were compared between the C2-C7 group and the C3-C7 group. All planes were also classified as segments with compression or noncompression, and the differences in backward shift were compared. Results: There were no significant differences in Japanese Orthopedic Association score between the C2-C7 and C3-C7 groups at final follow-up and no significant differences in the overall backward shift between the 2 groups. The spinal cord shift of C1, C2, and C2/C3 segments and the segment of the largest shift distance were significantly different between the 2 groups; the spinal cord shift of the segments under compression was larger than that of noncompression. Conclusions: Surgery with upper extension to the C2 segment did not increase the overall spinal cord shift; 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.