Tables
Table 1 Baseline characteristics comparison between group A and group B
DOI: https://doi.org/10.21203/rs.3.rs-1069511/v2
Background:
Cervical spondylotic myelopathy patients with multiple segments are usually treated with surgery via the posterior approach, but expansive open laminoplasty (ELAP) often results in heavy, rigid, and acid bilge feelings in the neck, shoulder, and back, collectively known as axial symptoms.
Objective:
To evaluate the effect of modified posterior cervical ligament complex reconstruction and single-door laminoplasty with titanium plate fixation on postoperative axial symptoms in patients.
Methods:
We conducted a retrospective study including 132 cases of cervical spondylotic myelopathy at our institute from June 2016 to March 2018. Gender, age, operation time, intraoperative blood loss, post-operative drainage volume, and follow-up time, Visual analogue scoring (VAS), cervical curvature index (CCI) and the cross-sectional area of the posterior cervical muscles of the two groups were recorded.
Results:
There was statistical significance in the incidence of axial pain 3 months after surgery (P = 0.001), 6 months after surgery (P = 0.006), and 1 year after surgery (P = 0.015). Compared to group b, the VAS score in group A was decreased 1 week (P <0.0001), one month, 3 months (P=0.0001), 6 months(P=0.0076), and 1 year(P=0.0085) after surgery. The CCI and the posterior cervical muscle area also differed significantly between the two groups (P < 0.0001).
Conclusion:
Modified single open-door laminoplasty could relieve cervical axial pain in patients with cervical spondylotic myelopathy.
Cervical spondylosis is a syndrome characterized by a series of symptoms and signs due to various reasons, which stimulates or compresses the cervical nerve roots, spinal cord and blood vessels. Cervical spondylosis is currently divided into four types: cervical spondylotic myelopathy (CSM), cervical spondylotic radiculopathy (CSR), arteria vertebralis type (AVT), and sympathetic cervical spondylosis SCS) [1]. These types of cervical spondylosis could produce different symptoms spanning neck and back pain, limb weakness, finger numbness, abdominal band feeling, lower limbs cotton feeling, walking difficulties, dizziness, vomiting, blurred vision, tachycardia, swallowing difficulties, and other symptoms [2, 3]. When conservative treatment (including drugs, traction, acupuncture, massage, etc.) fails, surgery is an essential and effective treatment [4, 5]. For cervical spondylotic myelopathy with multiple segments (≥ 3 segments) (multiple cervical spondylotic myelopathy, MCSM) [6, 7], posterior decompression surgery is often used [8, 9]. Classic Hirabayashi open-door laminoplasty is a well-known procedure to treat cervical spondylotic myelopathy [10, 11] and can help to achieve satisfactory recovery of spinal function. However, axial symptoms are the most frequent complications following this surgery [12–14]. Axial symptoms were firstly described by Kawaguchi [13] in 1999 as chronic neck, shoulder and back pain after surgery [4, 13, 15–18]. Recent reports indicated that axial symptoms (neck and shoulder pain) are associated with damage to the cervical spinous process, posterior cervical ligaments, interspinous ligaments, and supraspinous ligaments [4, 19–21]. To relieve axial symptoms, we modified single open-door laminoplasty with reconstruction of the posterior spinous ligamental complex. We reconstructed the stability of the posterior cervical ligamental complex by retaining the spinous processes and reattaching them. This study assessed whether this modified surgical method could effectively relieve axial symptoms and identified the factors that help to improve post-operative axial symptoms.
General data
This is a retrospective single-center cohort study conducted in Qilu Hospital of Shandong University, Shandong province, China. A total of 132 patients with cervical spondylotic myelopathy admitted to the hospital from March 2016 to March 2018 were included. Inclusion criteria were patients with imaging data showing multiple segments cervical myelopathy (≥3 segments)(multiple myelopathy, MCSM), while other types of cervical spondylosis were excluded. The patients were divided into two groups. Group A included patients undergoing modified single open-door laminoplasty with titanium plate fixation and reconstruction of the cervical posterior ligamental complex, while patients in group B received the same open-door laminoplasty with fixation but without reconstruction of the cervical posterior ligamental complex. There patients were followed up for 1 year after operation. The outcomes were assessed using the cervical curvature index, VAS score, and cross-sectional area (CSA) of the erector muscle on CT scanning.
Surgical technique
Modified single open-door laminoplasty was designed to preserve the spinous process, supraspinal ligament, and unilateral paravertebral muscles. To perform the surgery, a midline skin incision was made from C3 to C6, while C2 and C7 were preserved because many posterior cervical muscles are attached to them. Part of the bottom of the C2 and C7 spinous process were removed by air drill to decompress a longer buffer for the backward movement of the spinal cord. The unilateral paravertebral muscles of the open side were dissected to expose the ipsilateral laminae. The spinous processes were cut at the base using bone shears. Subsequently, the contralateral paravertebral muscles and separated spinous processes were peeled off from the laminae to make a gutter on the hinge side. Finally, the lamina door was lifted, and a titanium micro-plate was placed to prevent its closure. The cut spinous processes, cervical posterior muscles, and ligaments were reset to the laminae and were firmly sutured.
General evaluation index
Age, gender，operation time, intraoperative blood loss, postoperative drainage volume, and follow-up time of the patients in group A and B were recorded and compared.
Axial symptoms (AS)
Visual analogue scoring (VAS)[18] was used to compare axial symptoms in the patients in group A and B 1, 3, 6 months, and 1 year after surgery. A score of 0 indicates no pain, 1-3 indicates mild pain (sleep is not affected), 4-6 indicates moderate pain (sleep is affected), and 7-10 indicates severe pain (sleep is severely affected). VAS score greater than 4 indicates severe axial pain [16]. The incidence of axial pain, severe axial pain, and VAS scores in the same time period were statistically compared between the two groups.
Cervical curvature index (CCI)
The CCI was measured using the ISHI-Hare method [22-24]. The C2 to C6 vertebral posterior margin on X-ray was connected to create the R line for all patients before and after surgery. The R line was perpendicular to the posterior edge of the C3, C4, and C5 vertebrae. Their distances were respectively expressed as r1, r2, r3, and CCI = Σri/R. The pre- and post-operative CCI values between the two groups were statistically compared.
Measurement of the muscle cross-sectional area (CSA) of the posterior cervical spine
The cross-sectional area of the posterior cervical muscles was measured using a method previously described by Fujimura [22]. The cross-sectional area of the posterior cervical muscles at the level of C3/4, C4/5, and C5/6 discs was measured by Photoshop on preoperative and post-operative CT films. The total area of the muscles at the back of the cervical vertebra was measured by 3 cross-sectional areas, and the cross-sectional area and total cross-sectional area of the two groups were statistically compared.
Statistical method
The relevant data collected were analyzed by SPSS 24.0 statistical software. Pearson’s correlation analysis was used for the correlation data. Continuous categorical variables were analyzed using the t test and chi-square test, respectively. P < 0.05 indicated statistically significant differences (* P < 0.05, ** P < 0.01, and *** P < 0.001).
Baseline characteristics of patients in the study.
All patients were completely followed up for this study. Two patients in group A died 50 and 60 days after surgery due to respiratory and digestive diseases. One patient in group B died 30 days after surgery due to digestive system disease. The follow-up was terminated one year after surgery. There was no statistically significant difference in age，gender，operation time，intraoperative and post-operative blood loss, follow-up time between group A and B. (table 1)
Preoperative and post-operative imaging data of patients in group A and B
The preoperative and post-operative imaging data of the patients in group A and B were compared (fig 1). All of the patients in group A and B achieved bone healing (postoperative imaging showed no bone defect or edema around the internal implant, and the position of the internal fixation was satisfactory) in post-operative examinations. There was no loosening, slipping, or fractures of the internally fixed titanium plates and screws. None of the patients presented with increased neurological symptoms.
AS and postoperative outcomes between group A and B
The incidence of AS in group A and B was not statistically significant one month after surgery. However, group B had significantly higher incidence of AS 3 months, 6 months, and 1 year after surgery (fig 2a). Similar results were observed for severe AS in the two groups (fig 2b). At each time point after surgery, the VAS scores differ significantly between group A and B (fig 3). There was no difference in preoperative CCI values of patients in the two groups. However, patients in group A had lower CCI compared to those in group B. The preoperative and post-operative CCI values of patients in the group A were not different, while patients in group B had higher CCI post-operative CCI values compared to their preoperative value (fig 4a), Next, we compared the changes of preoperative and post-operative CCI value between group A and B, and patients in group A had less change in CCI value after surgery than group B (fig 4b). Finally, we also compared the preoperative and post-operative changes in the posterior cervical muscle area between group A and B. The results showed that patients in group A were associated with significantly smaller changes in the posterior cervical muscle area of the C3/4, C4/5, C5/6 levels, and the total posterior cervical muscle areas (fig 5).
Cervical spondylosis is a degenerative disease. The main causes include chronic fatigue, cervical disc herniation, osteogenesis, arthritis, ligament thickening and ossification, and trauma. These disorders cause severe clinical symptoms due to compression to the spinal cord, nerve roots, vertebral arteries, and sympathetic nerves [25]. Cervical spondylosis is divided into four types: cervical spondylotic myelopathy, cervical spondylotic radiculopathy, arteria vertebralis, and sympathetic cervical spondylosis [26]. For most patients, conservative symptomatic treatment with medications, acupunctures, tractions, and massages could relieve symptoms. However, for a few patients, conservative treatment may not be effective, and the symptoms may be aggravated over time, causing continuous pain. Posterior cervical surgery has been used as an alternative method since 1950 to treat cervical spondylosis. The advantage of posterior cervical spine surgery is that it avoids damage to the trachea, esophagus, important blood vessels, and nerves in front of the cervical spine, thus reducing the risk of surgery [27]. However, the posterior cervical spine also has its own defects, which can break down in the rear of the cervical muscle ligament complex, result in the destruction of the cervical vertebra rear anatomical structure and loss of stability [28, 29], and cause post-operative stiffness, acid bilges, and pain in the neck, shoulder, and back, called axial symptoms (AS) [13]. After decades of development, single open-door laminoplasty has become a major surgical method for the treatment of multilevel cervical spondylotic myelopathy [1]. To alleviate axial symptoms after surgery, this surgical method has been continuously improved in clinical work, including posterior reconstruction, minor invasive surgery, and internal fixation [30–32]. In reconstructive surgery, expanded laminoplasty with preserved posterior spinous ligament complex proposed by Kawaguchi et al. could significantly alleviate axial symptoms in patients after surgery [33]. This modified surgical method restores the anatomical structure of the back of the cervical vertebra to the full extent, increasing the stability of the cervical vertebra after surgery, guaranteeing the physiological curvature and post-operative mobility of the cervical vertebra.
We conducted this retrospective study to further explore whether modified single open-door laminoplasty with reconstruction of the posterior spinous ligament complex (MLRP) has a significant effect on relieving axial symptoms after surgery and explore the possible factors leading to this result. Through analysis of the collected data, we found that the occurrence and severity of post-operative axial pain were not correlated with age, gender, operation time, intraoperative blood loss, and post-operative drainage volume of patients. In terms of the post-operative VAS scores, there was no statistical difference in the incidence of axial pain 1 month after surgery between groups A and B; However, the difference was significant 3 months, 6 months, and 1 year after surgery. The procedure did not reduce the incidence of post-operative axial pain in the first month post-surgery, but during the next follow-up from 3 months to 1 year, the incidence of AS in group A was significantly lower than in group B. No patients in group A no longer suffered from severe axial pain 1 month after surgery, while the patients in group B still suffered from severe axial pain until 1 year after surgery. Generally speaking, compared with traditional single open-door laminoplasty, the modified surgical method with reconstruction of the posterior spinous ligament complex has obvious advantages in relieving patients' post-operative axial pain. The occurrence of post-operative axial pain in group A was significantly lower than in group B.
To study the reasons leading to this advantage, we measured the preoperative and post-operative X-rays of the patients in groups A and B, calculated the cervical curvature index (CCI) value of the patients, and conducted a statistical comparison. In group A, the comparison of the CCI values before and after surgery was not statistically changed, while in group B, the CCI values before and after surgery was statistically decreased. In addition, the changes between postoperative CCI and preoperative CCI in the two groups was also statistically significant. This proves that traditional single open-door laminoplasty significantly changes the curvature of patients' cervical vertebra because of instability and destroys the posterior cervical muscle-ligament complex and spinous processes. The instability of the cervical spine after single open-door laminoplasty was regarded as the main reason for the reduction in post-operative axial pain, leading to post-operative rehabilitation.
However, MLRP may protect the muscles and ligaments that maintain the stability of the cervical spine. We analyzed the pre- and postoperative CT slices on the cervical back muscle cross-sectional areas. The results showed that the change in the value of the posterior cervical muscle cross-sectional area in group A was significantly lower than in group B, which may be because simple single open-door laminoplasty destroys the adhesion point of the muscle behind the spinous process, leading to significant post-operative muscle atrophy. This may be another important factor in the relief of post-operative axial pain in patients who undergo MLRP.
This retrospective study confirmed that MLRP could be of considerable significance in relieving patients' AS after surgery. Two relative factors are post-operative changes in the cervical curvature index and the cross-sectional area of the posterior cervical muscles. MLRP protects the posterior cervical muscles and prevents instability of the cervical spine via the reconstruction of the posterior cervical muscle-ligament complex and spinous processes. This study provides a novel alternative surgery to decrease axial pain in patients with cervical spondylotic myelopathy.
The incidence and severity of postoperative axial symptoms are significantly lower after modified single open-door laminoplasty with reconstruction of the posterior spinous ligament complex than the simple single open-door laminoplasty. This result could be related to changes in the cervical curvature index and the degree of atrophy of the posterior cervical muscles affected by the reconstruction of the posterior spinous process ligament complex of the cervical spine.
CSM, cervical spondylotic myelopathy,
CSR, cervical spondylotic radiculopathy,
AVT, arteria vertebralis type,
SCS, sympathetic cervical spondylosis,
CT, computed tomography,
MRI, magnetic resonance image,
MCSM, multiple cervical spondylotic myelopathy,
AS, axial symptoms,
CCI, cervical curvature index,
VAS, visual analogue scale,
ELAP, expansive open-door laminoplasty
Ethics approval and consent to participate
The protocol was reviewed and approved by the Medical Ethics Committee of Qilu Hospital of Shandong University (Ethical Approval: Grant no.：KYLL-2017-372). All steps of the study were in accordance with the ethical standards. All methods were carried out in accordance with relevant guidelines and regulations by the medical ethics committee, and written informed consent was obtained from all the participants.
Consent for publication
Not applicable.
Availability of data and materials
All data analyzed during this step of study are included in this published article.
Competing interests
The authors declare that they have no conflict of interest.
Funding
This study was supported by the National Natural Science Foundation of China (grant number 81601067), the Medical Science Development Program of Shandong Province, China (grant number 2016WS0361).
Authors’contributions
Yayun Zhang and Hua Zhao wrote the main manuscript text , Liangxi Chen and Meipeng Zhu prepared figures 1-3, Yimin Dong, Renpeng Peng and Hongwei Zhao prepared figures 4-5, and XinPan prepared table1. All authors reviewed the manuscript.
Acknowledgements
The authors appreciate the participants in this study.
Table 1 Baseline characteristics comparison between group A and group B