DOI: https://doi.org/10.21203/rs.3.rs-2216358/v1
Lumbar spinal stenosis (LSS) is a common clinical degenerative disease of the spine. It is mainly caused by degeneration and hyperplasia of the lumbar spinal canal and lateral axilla due to aging, which leads to spatial compression of the spinal canal and aggravates the compression of blood vessels and nerve tissues. Indirectly causes pain and numbness in the waist and lower limbs, which may lead to limb dysfunction and claudication in severe cases [1]. In clinical diagnosis, there are some differences between symptomatic and radiation-induced LSS patients, which increases the difficulty of clinical diagnosis and treatment to some extent. Therefore, it is of great significance to explore new typical imaging signs of LSS for its diagnosis and treatment. Redundant nerve roots (RNRs) is a typical clinical sign, which mainly refers to the tortuousness and relaxation of the cauda equina nerve in the spinal canal. RNRs can be used as a reliable indication for clinical surgical treatment of LSS. However, the relationship between RNRs formation and LSS and other disease factors and the mechanism of action have not been clarified [2–3]. This study aims to analyze the Magnetic Resonance Imaging (MRI) features of RNRs in LSS patients with low back and leg pain and its correlation with various disease factors in LSS patients, so as to provide a reference for the subsequent clinical diagnosis and treatment of LSS.
Affected by various factors, when the central lumbar spinal canal stenosis reaches a certain degree, the dural sac will compress and deform and exert pressure on the cauda equina nerve, indirectly restricting the normal activities of patients. In lumbar spine bending state, horsetail nerve by drawing up and through the narrow place, and after lumbar back upright or stretched state, horsetail nerve can only rely on their own anatomy, maintain structure and gravity reset itself, leading to the present at the narrow level relaxation and winding, the distribution characteristics of these patients have a long-term symptoms of low back pain and restricted movement performance, MRI imaging findings were mostly disc bulging, ligamentum flavum hypertrophy, severe spinal stenosis, and lumbar osteoarthritis [4].
The results of this study showed that "rattan cord" type RNRs was the main MRI imaging feature, accounting for 30%, which was consistent with the results of previous studies [5]. From the perspective of imaging analysis, the "rattan cord" type did not show obvious tortuosity and winding, and its nerve descending was relatively smooth, which belongs to the early image sign change of RNRs. The "grape beaded" type aggravated tortuosity, and the nerve descending was in a certain state of distortion, which belongs to the middle stage image change of RNRs. However, the cauda equina nerve is surrounded by "massive" and coiled "serpentine type" image features with obvious tortuous and descending nerve characteristics. In this state, the cauda equina nerve is severely ischemic and hypoxic, which will further lead to cauda equina syndrome and limit the patient's urination and defecation function [6].
Previous studies have pointed out that there is a significant relationship between the occurrence of RNRs and LSS, and the relationship between the image manifestations of RNRs and the postoperative efficacy of LSS patients has not been clarified. Some studies believe that LSS patients with positive RNRs have a worse prognosis and more severe symptoms of limb numbness and back and leg pain [7].
The results of this study showed that age, ODI score, female sex, lumbar 4/5 lumbar spinal stenosis, sharp protrusion and multi-segmental stenosis were all risk factors for RNRs, which were basically consistent with previous studies. The mechanism of action was analyzed as follows: The lumbar spine of elderly patients often has degenerative abnormal changes, accompanied by a certain degree of lumbar spinal stenosis. In this state, the pressure of cauda equina nerve and dural sac of patients is aggravated. After 50% Cauda equina nerve compression, there will be local increased signal, and the nerve fiber breakage and vacuole formation. Horsetail nerve compression at the 75% level image shows the interrupt signal, and part of the nerve fibers disappeared, so can show the main reason for the elderly patients occurred RNRs may be as we age, in patients with lumbar spinal stenosis is aggravating, increasing on the surrounding horsetail nerve compression at the same time, which makes it the chronic compression of nerve root is aggravating, Eventually, RNRs are triggered [8]. Studies have pointed out that female patients with LSS is RNRs high-risk groups, but no statistical difference was found between the data, and the women in this study is to increase RNRs a different risk factors, the reason may be that the patient's age, regional culture and the differences in sample size data deviation, the follow-up should be further in-depth study [9]. This study shows that the position of lumbar spinal stenosis is related to RNRs. The reason why the position of lumbar spinal stenosis higher than L4 increases the risk of RNRs is mainly because there are more nerve roots above L4, so the caudal equina nerve is vulnerable to extrusion and friction when passing through the stenosis, leading to fibrous degeneration and demyelination, and further increasing the risk of RNRs [10]. Some studies have pointed out that the sharp protrusion in the stenosis belongs to calcified nucleus pulposus and posterior margin hyperplasia of the vertebral body, but not the sharp protrusion belongs to thick ligament hypertrophy, thus increasing the risk of RNRs formation, which is consistent with the results of this study. Multistage spinal canal stenosis is a superposition of the risks of multiple single-segment stenosis, which further aggravates the compression of the cauda equina nerve root and the friction between the cauda equina nerve and the dural sac, and ultimately increases the risk of RNRs formation [11].
In this study, the effective sagittal diameter and median sagittal diameter in the spinal canal can be used as sensitive indicators to reflect the stenosis of the median spinal canal, while the effective cross-sectional area of the spinal canal can directly reflect the degree of lumbar spinal canal stenosis. ODI score is a good indicator to evaluate the pain of patients. Therefore, this study and the selection of the above four items as evaluation indicators for the evaluation of the degree of spinal stenosis and pain can provide a reliable basis for the mechanism analysis of the relationship between LSS related indicators and the formation of RNRs [12]. According to this study, the effective sagittal diameter, the median sagittal diameter, effective cross-sectional area, the formation of protective factors and ODI RNRs are risk factors, thus effectively sagittal diameter, the median sagittal diameter, effective cross-sectional area three indicators and ODI increase said stenosis is aggravating, the reason is that RNRs formation is mainly caused by vertebral canal volume to reduce, It is not only caused by the compression of the spinal canal by the protrusion behind the vertebral body, but also the smaller the effective cross-sectional area of the spinal canal in the segment of lumbar spinal stenosis and the more severe the degree of stenosis, the higher the incidence of RNRs. The degree of spinal stenosis is an important reason for the performance of RNRs [13].
From January 2021 to June 2022, 100 LSS patients who were admitted to our hospital due to back and leg pain were selected for analysis. The age was 53–73 years old (59.83.45 ± 3.66) years old, the male and female ratio was 53/47, and the educational level of technical secondary school and below, college and above were 47 cases and 53 cases, respectively. There were 43 cases of diabetes, 46 cases of coronary heart disease, 31 cases of smoking and 30 cases of drinking. The included subjects met the requirements of clinical MRI examination and LSS diagnostic criteria [14], with complete clinical data and aged 18 years and above. The included subjects were excluded from the study if they had any combination of lumbar tumor, nervous system injury, congenital lumbar spinal stenosis, history of spinal trauma, history of previous lumbar surgery, and lumbar spinal stenosis. According to the occurrence of RNRs, the patients were divided into positive group and negative group, with 30 cases in positive group and 70 cases in negative group.
Clinical data table using the collect information of the object of study, age, gender, educational level, history of basic diseases, cervical stenosis position, more narrow situation, highlight the sharp, vertebral canal effective radius vector, the center of the vertebral canal sagittal diameter and vertebral canal effective cross-sectional area three prominent plane vertebral MRI imaging tests such as line of pipe diameter and area of the image parameters and other information.
Mag-netom Avanto, a 1.5-T superconducting MR detector manufactured by Siemens and 8-channel phased front coil were used for MRI examination. Scanning patients replace certain cotton inspection before foreign bodies in the scan bed and took supine, some patients can be used soft mat mat high leg, wear earmuffs, Z axis flat body midline, the X axis two specified above the umbilicus, MR scan was carried out on the lumbar part, scanning sequence including spin echo and fast spin echo pulse sequence scanning technology,, The scanning field, layer thickness, TR and TE parameters in T1WI sagittal view were 280 mm, 4.0 mm, 550 ms and 8.4 ms, respectively. Above sagittal parameters on T2WI were 280 mm, 4.0 mm, 4000 ms and 105 ms, respectively. The parameters above the sagittal position of T2WI-TIRM were 280 mm, 4.0 mm, 5000ms and 63 ms. The scanning field, layer thickness, TR and TE parameters of T2WI-MSMA axis were 200 mm, 4.0 mm, 5000 ms and 103 ms, respectively. All images were transferred to a post-processing workstation and evaluated and measured by a professional radiologist with more than 2 years of experience.
The lumbar MRI T2 axial image information was imported into the PACS system, and the supporting software was used to measure the vertebral canal diameter line and area related parameters in the protrusion plane, including the median sagittal diameter of the vertebral canal, the effective sagittal diameter of the vertebral canal and the effective cross-sectional area of the vertebral canal. The straight distance from the midpoint of the posterior edge of the vertebral body to the midpoint of the posterior wall of the vertebral canal was the median sagittal diameter of the vertebral canal. The straight distance from the midpoint of the posterior margin of the herniated disc to the midpoint of the posterior wall of the spinal canal was the effective sagittal diameter of the spinal canal, as shown in Fig. 1. The area enclosed by the herniated intervertebral disc at the strictest level and the bilateral hypertrophic ligamentum flavum shows the effective cross-sectional area of the spinal canal.
Oswestry Disability Index (ODI) was used to evaluate the function of patients from 9 dimensions, including pain degree, sexual life, self-care ability of daily living, lifting, walking, sitting, standing, sleeping, social activities and travel. Each dimension was scored from 0 to 5, with a total score of 0 to 45. The pain increased as the score increased.
Data were input into SPSS 26.0 software for processing, measurement data were expressed as mean ± standard deviation (‾x ± s) t-test; Count data were represented by (%), x² test; Multivariate Logistic regression was used to analyze the influencing factors of postoperative RNRs in patients with LSS. P < 0.05 indicated statistical difference.
A total of 30 cases of RNRs were included in this study, including 20 cases of "rattan cord" type with parallel tortuous distribution of cauda equina nerve in the spinal canal, and 4 cases of "grape string" type with tortuous distribution of "grape string" around the cauda equina nerve in the spinal canal. The cauda equina nerve in the spinal canal was "serpentine" type with "oval serpentine" curling and clumped distribution in 6 cases. Attached Fig. 3.
Note
3A is "Rattan cord" type, 3B is "grape beaded" type, 3C is "serpentine" type.
The age, female proportion and ODI score of the positive group were significantly higher than those of the negative group (P < 0.05), and there was no statistically significant difference between education level and history of other diseases (P > 0.05). Table 1. Spearman correlation analysis showed that ODI score was positively correlated with the incidence of RNRs (r = 0.766, P = 0.000).
| factor | n | Positive group(n = 30) | Negative group(n = 70) | t/x2 | P |
|---|---|---|---|---|---|
| Age (year) | - | 67.45 ± 5.45 | 56.56 ± 3.12 | 12.617 | < 0.001 |
| sex | 4.590 | 0.032 | |||
| man | 53 | 11 | 42 | ||
| woman | 47 | 19 | 28 | ||
| degree of education | 0.231 | 0.631 | |||
| Technical secondary school and below | 47 | 13 | 34 | ||
| College degree or above | 53 | 17 | 36 | ||
| History of diabetes | 0.701 | 0.402 | |||
| yes | 43 | 11 | 32 | ||
| deny | 57 | 19 | 38 | ||
| History of coronary heart disease | 0.276 | 0.599 | |||
| yes | 46 | 15 | 31 | ||
| deny | 54 | 15 | 39 | ||
| History of smoking | 3.048 | 0.081 | |||
| yes | 31 | 13 | 18 | ||
| deny | 69 | 17 | 52 | ||
| History of drinking | 0.907 | 0.341 | |||
| yes | 30 | 11 | 19 | ||
| deny | 70 | 19 | 51 | ||
| ODI grade | 27.45 ± 2.21 | 16.44 ± 2.02 | 24.280 | < 0.001 |
4.3 Statistical analysis of differences in factors and imaging parameters of lumbar stenosis between positive and negative groups
The proportions of lumbar 4/5 lumbar spinal stenosis, sharp protrusion, and multi-segment stenosis in the positive group were significantly higher than those in the negative group, and the effective sagittal diameter, median sagittal diameter, and effective cross-sectional area were significantly lower in the positive group, with statistical differences (P < 0.05). Table 2.
| factor | n | Positive group(n = 30) | Negative group(n = 70) | t/x2 | P |
|---|---|---|---|---|---|
| The narrow position | 4.417 | 0.036 | |||
| Waist 2 / 3 | 16 | 3 | 13 | ||
| Waist 3 / 4 | 30 | 6 | 24 | ||
| Waist 4 / 5 | 54 | 21 | 33 | ||
| Highlight the sharp situation | 8.007 | 0.005 | |||
| yes | 42 | 19 | 23 | ||
| deny | 58 | 11 | 47 | ||
| Multisegment stenosis condition | 6.338 | 0.012 | |||
| yes | 38 | 17 | 21 | ||
| deny | 62 | 13 | 49 | ||
| Effective vector diameter (mm) | 7.34 ± 1.45 | 11.45 ± 2.12 | -9.679 | < 0.001 | |
| Mid-point sagittal diameter (mm) | 13.23 ± 4.45 | 19.67 ± 5.31 | -5.820 | < 0.001 | |
| Effective cross-sectional area (mm2) | 65.33 ± 4.32 | 87.78 ± 6.44 | -17.459 | < 0.001 |
4.4 Multivariate Logistic analysis of the relationship between RNRs and disease factors in patients with lumbar spinal stenosis
Will P < 0.05 factor was used as the independent variable, and RNRs was used as the dependent variable for multivariate Logistic analysis.Age, ODI score, female sex, lumbar 4/5 lumbar spinal stenosis, sharp protrusion and multi-segmental stenosis were all risk factors for RNRs, and effective sagittal diameter, median sagittal diameter and effective cross-sectional area were protective factors. Table 3–4, FIG. 4.
| factor | variable name | assignment |
|---|---|---|
| Age (year) | X1 | ≥ 80 = 1, ༜80 = 2 |
| sex | X2 | Female = 1, male = 2 |
| lumbar spinal stenosis | X3 | Waist 2 / 3 = 1, waist 3 / 4 = 2, waist 4 / 5 = 3 |
| Highlight sharp | X4 | Yes = 1, No = 2 |
| Multisegmental stenosis | X5 | Yes = 1, No = 2 |
| ODI grade | X6 | - |
| Effective sagittal diameter | X7 | - |
| The center sagittal diameter | X8 | - |
| net sectional area | X9 | - |
| RNRs | Y | Yes = 1, No = 2 |
| influencing factor age | B | S.E. | Wald | P | OR | 95%CI | |
|---|---|---|---|---|---|---|---|
| toplimit | lower limit | ||||||
| Gender (female) | 1.05 | 1.215 | 4.561 | 0.023 | 0.236 | 0.042 | 0.886 |
| Highlight sharp | 3.38 | 1.233 | 6.985 | 0.006 | 0.128 | 0.016 | 0.636 |
| Multisegmental stenosis | 1.192 | 0.365 | 9.013 | 0.000 | 0.082 | 0.015 | 0.411 |
| Position of lumbar spinal stenosis (waist 4 / 5) | 3.278 | 1.122 | 6.974 | 0.004 | 0.127 | 0.007 | 0.632 |
| ODI grade | 1.048 | 1.224 | 4.569 | 0.032 | 0.225 | 0.049 | 0.875 |
| Effective sagittal diameter | 1.181 | 0.354 | 9.002 | 0.000 | 0.073 | 0.011 | 0.400 |
| The center sagittal diameter | -0.182 | 0.211 | 7.035 | 0.007 | 0.831 | 0.409 | 1.248 |
| net sectional area | -0.088 | 0.190 | 9.063 | 0.001 | 0.923 | 0.539 | 1.298 |
| influencing factor | -0.252 | 0.082 | 7.024 | 0.005 | 0.781 | 0.620 | 0.944 |
In conclusion, "rattan cord", "grape string" and "serine" are typical imaging changes of RNRs. Older age, female age, position of lumbar spinal stenosis, sharp protrusion, multi-segmental stenosis, ODI score, dural sac area at the stenosis level, effective sagittal diameter, median sagittal diameter, and effective cross-sectional area are the main influencing factors of RNRs formation. RNRs can be used as a new target for clinical diagnosis and treatment of LSS.
Ethics approval and consent to participate
All methods were carried out in accordance with relevant guidelines and regulations. The study was approved by the Affiliated Hospital of Chengde Medical College’s ethics committee.
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Competing interests
The authors declare that they have no competing interests.
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Yawen Cao contributed to the conception of the study, Dan Zhang performed the experiment and performed the data analyses, Shenglin Wang wrote the manuscript. All authors read and approved the fnal manuscript.
None.
[Abstract] Backgroud: To investigate the magnetic resonance imaging (MRI) characteristics of Cauda equina nerve redundancy (RNRs) in patients with lumbar spinal stenosis (LSS) and low back and leg pain and its correlation with clinical risk factors. Methods: A total of 100 LSS patients admitted to our hospital due to back and leg pain from January 2021 to June 2022 were selected and analyzed. According to the occurrence of RNRs, they were divided into positive group and negative group, with 30 cases in the positive group and 70 cases in the negative group. The "rattan cord" type was the main type of RNRs, accounting for 30.00%. Results: Compared with the negative group, age, female, lumbar 4/5 spinal stenosis, sharp protrusion, multi-segment stenosis, and significantly increased ODI score in the positive group were all risk factors for RNRs. The effective sagittal diameter, median sagittal diameter and effective cross-sectional area of the positive group were significantly decreased and were protective factors for RNRs. ODI score was positively correlated with the incidence of RNRs (P < 0.05). The main MRI image change of RNRs is "rattan cord". Conclusion: The formation of RNRs is affected by many factors, such as age, gender, position of lumbar spinal stenosis, sharp protrusion, multi-segmental stenosis, ODI score, effective sagittal diameter, median sagittal diameter, effective cross-sectional area and so on.
[Keywords] Cauda equina nerve redundancy; Lumbar spinal stenosis; Lumbocrural pain; Correlation; Magnetic resonance (NMR); Lumbar spinal stenosis
All the experiments, including any relevant details were approved by Affiliated Hospital of Chengde Medical College.
We confirmed that informed consent was obtained from all subjects and/or their legal guardian(s).