For patients with multilevel CMR, especially those with kyphosis, the selection of an operative procedure remains controversial. The aims of surgical treatment were not only to decompress the spinal cord and nerve root but also to restore cervical curvature by reconstructing the lordotic alignment. Traditional posterior laminoplasty or laminectomy is not sufficient to decompress nerve root compression and can even cause stretching of the nerve root due to backward shifting of the spinal cord.
Further excision of the inside edge of the facet joints could decompress the nerve foramina. Tanaka et al. found that the neural foramen is a funnel-shaped structure where the nerve root extending from the spinal cord is the widest and the root localization is the narrowest. Thus, this is the common location of compression in cases of intervertebral foramen stenosis. This anatomical characteristic provides evidence for enlarged laminectomy. The technique of foraminotomy has been continually developed since the 1990s with a satisfying result of decompressing the nerve root and preventing nerve root paralysis [7–10]. No significant complications, such as cervical instability, were noted in this study.
In this study, the ability of EL-LMSF procedure to relieve spinal cord and nerve root symptoms and correct cervical curvature was evaluated. Enlarged laminectomy was performed over a mean of 2.39 levels, and no nerve foramen was decompressed in the ACCF group. Moreover, the EL-LMSF procedure was performed with a shorter operation time and less blood loss. The JOA score was used to evaluate spinal cord function, and the VAS score was used to evaluate neck nerve root function. Corrected cervical alignment was used to evaluate radiological efficacy. No difference in JOA score was noted between the two surgical measurements. Patients treated with EL-LMSF indicated with lower VAS for neck (1.3 ± 1.7vs. 3.3 ± 1.3, P = 0.003) and better cervical lordosis (10.7 ± 4.2° vs. 8.5 ± 3.5°, P = 0.013). A lower VAS for neck and better cervical lordosis were noted in patients treated with EL-LMSF compared with the ACCF group. Thus, the EL-LMSF procedure has obvious advantages in relieving nerve root symptoms and correcting cervical curvature. Radiology assessments showed that the use of a prebent titanium rod and Mayfield frame in the surgery could help to restore lost cervical curvature properly and prevent curvature loss.
During the follow-up period, 15.2% of patients developed postoperative complications in the ACCF group, including 2 cases with transient dysphagia, 1 case with C5 palsy, 1 case with axial symptoms, and 1 with screw pullout. However, 9.5% of patients developed postoperative complications in the EL-LMSF group, including 3 cases of axial pain and 1 case of epidural hematoma. Therefore, the EL-LMSF procedure for the treatment of multilevel CMR was indicated to be a safer strategy given its reduced level of complications; however, axial pain was unavoidable.
The incidence of axial symptoms after laminectomy or laminoplasty can be as high as 30% [11, 12]. However, the underlying mechanism remains unclear. Du W et al. suggested that axial symptoms were related to cervical kyphotic deformity . It has also been reported that lateral retraction of paravertebral muscles attached to the cervical spine and removal of the lamina and ligamentum flavum in laminectomy, especially the semispinalis attached to the C2 spinous process, increases flexion mechanical stress, which may be a significant factor in the development of axial symptoms . Motosuneya et al. reported that reconstruction of the posterior tension band for cervical stenotic myelopathy decreased the incidence of axial pain . The study demonstrated that 11.9% of patients complained of postoperative axial pain around the neck and shoulder, most occurred in patients with obvious cervical kyphosis. We hypothesize that lower axial symptom severity after surgery may correlate with reconstruction of the cervical posterior tension band and restoration of cervical curvature. However, few high-quality clinical trials have reported this association.
In his retrospective analysis, Kaneyama S et al. reported that the incidence of postoperative C5 palsy was 4.6% (0 to 30%). In this study, the ACCF group had a patient with C5 palsy, whereas none of the patients in the EL-LMSF group experienced this condition. This result demonstrates that enlarged laminectomy can prevent the occurrence of postoperative C5 palsy, and many other studies have reported similar findings [16– 18].
In conclusion, enlarged laminectomy requires a longer surgical time and results in more blood loss compared with the ACCF procedure. However, the procedure has obvious advantages in relieving nerve root symptoms and correcting cervical curvature with fewer postoperative complications. EL-LMSF for the treatment of multilevel CMR is an effective and safe strategy for relieving nerve root symptoms and restoring cervical curvature. However, high-quality, large-scale clinical trials with long-term follow-up are urgently warranted.