Preservation of Muscles Attached to the C2 and C7 Spinous Processes Rather Than Subaxial Deep Extensors Reduces Adverse Effects After Cervical Laminoplasty

Study Design. Prospective study. Objective. To examine whether preservation of subaxial deep extensor muscles plays any significant role in reducing axial neck pain and unfavorable radiologic changes after cervical laminoplasty in patients with cervical spondylotic myelopathy and to confirm the benefits of preserving muscles attached to the C2 and C7 spinous processes. Summary of Background Data. Axial neck pain and unfavorable radiologic changes after cervical laminoplasty have been reported to mostly result from detachment of cervical extensor muscles, particularly muscles attached to the C2 and C7 spinous processes. Other surgeons have reported that preservation of subaxial deep extensor muscles reduces these adverse effects after cervical laminoplasty. Methods. Subjects comprised 36 patients with cervical spondylotic myelopathy who underwent C3-C6 open-door laminoplasty and were followed up for >24 months. Of these, 18 consecutive patients underwent our modified laminoplasty (muscles-preserved group) and the remaining 18 consecutive patients underwent the conventional procedure (muscles-disrupted group). Both procedures preserved all muscles attached to the C2 and C7 spinous processes. Subaxial deep extensor muscles on the hinged side were also preserved in the muscles-preserved group. Radiologic and clinical data were prospectively collected. Results. Both groups achieved equal neurologic improvement. Frequencies of axial neck pain showed no significant differences between groups. This value did not vary according to the side of preservation of subaxial deep extensor muscles or the side of muscle disruption. Postoperative loss of lordosis and range of motion of the cervical spine also demonstrated no significant difference between groups. Conclusion. These results indicate that preservation of subaxial deep extensor muscles plays no significant role in reducing axial neck pain and unfavorable radiologic changes after cervical laminoplasty, supporting the hypothesis that these adverse effects after laminoplasty largely result from detachment of muscles attached to the C2 and C7 spinous processes.