Retrospective cohort study between selective and standard C3-7 laminoplasty. Minimum 2-year follow-up study

Abstract

A total of 64 patients with cervical spondylotic myelopathy (CSM) were assessed in this study. Forty-two patients underwent selective expansive open-door laminoplasty (ELAP). Twenty-two patients who underwent conventional C3-7 ELAP served as controls. There were no significant differences in recovery rate of JOA scores, C2-C7 angle or cervical range of motion between two groups. Incidence of axial symptoms and segmental motor paralysis in selective ELAP was significantly lower than those in the C3-7 ELAP. Size of anterior compression mass, postoperative spinal cord positions and decompression conditions were evaluated using preoperative or postoperative MRI in 50 of 64 patients. There was a positive correlation between number of expanded laminae and maximum anterior spaces of spinal cord. Incomplete decompression was developed in three of 37 patients in selective ELAP and in two of 13 patients in C3-7ELAP. Mean size of anterior compression mass at incomplete decompression levels was significantly greater than that at complete decompression levels. Since, there was less posterior movement of the spinal cord in selective ELAP than that in C3-7ELAP, minute concerns about size of anterior compression mass is necessary to decide the number of expanded laminae. Overall, selective ELAP was less invasive and useful in reducing axial symptoms and segmental motor paralysis. This new surgical strategy was effective in improving the surgical outcomes of CSM, and short-term results were satisfactory.

Fig. 1

Case presentation of selective ELAP. a Preoperative MRI shows three-level stenosis from C4/5–C6/7. The stenosis levels were defined by the disappearance of the subarachnoid space. b Intraoperative photograph. In this three levels stenosis case, the laminae from C4 to C6 laminae were opened in conjunction with upper half laminectomy of C7. c Postoperative MRI

Fig. 2

Size of anterior compression mass and anterior space of spinal cord. Figure shows C4–C6 expansive open-door laminoplasty in conjunction with C7 upper half laminectomy of three-level stenosis case. A baseline (dotted line) was drawn to link the middle point of posterior vertebral body margin and the anterior compression mass (a) and anterior space of the spinal cord (b) were measured at the disc levels

Fig. 3

Anterior space of spinal cord. The anterior space of spinal cord increased in the middle position of the laminoplasty. The maximum anterior space of spinal cord showed a tendency to increase in proportion to the number of expanded laminae

Fig. 4

Maximum anterior space of spinal cord associated with number of expanded laminae. There was a significant correlation between the maximum anterior space of spinal cord and the number of expanded laminae (r = 0.38, P = 0.006)

Fig. 5

Size of anterior compression mass associated with postoperative decompression condition. The mean size of anterior compression mass was 6.4 ± 0.2 mm at incomplete decompression levels and 3.7 ± 0.1 mm at complete decompression levels (P < 0.001)