Biomechanical analysis of cervical spondylotic myelopathy: the influence of dynamic factors and morphometry of the spinal cord

Objective

Patients with cervical spondylotic myelopathy (CSM) have the same clinical symptoms that vary according to the degree of spinal cord compression and the cross-sectional cord shape. We used a three-dimensional finite element method (3D-FEM) to analyze the stress distributions of the spinal cord with neck extension under three cross-sectional cord shapes.

Methods

Experimental condition for the 3D-FEM spinal cord, ligamentum flavum, and anterior compression shape (central, lateral, and diffuse types) was established. To simulate neck extension, the spinal cord was extended by 20° and the ligamentum flavum was shifted distally according to movement of the cephalad lamina.

Results

The stress distribution in the spinal cord increased due to invagination of the ligamentum flavum into the neck extension. The range of stress distribution observed for the diffuse type was wider than for the central and lateral types. In addition, the stress distribution in the spinal cord was increased by the pincer movement of the ligamentum flavum and by the anterior compression of the spinal cord. The range of stress distribution observed for the diffuse type under antero-posterior compression was also wider than for the central and lateral types.

Conclusion

This simulation model showed that the clinical symptoms of CSM due to compression of the diffuse type may be stronger than for the central and lateral types. Therefore, careful follow-up is recommended for anterior compression of the spinal cord of diffuse type.     

Biomechanical analysis of cervical spondylotic myelopathy: The influence of dynamic factors and morphometry of the spinal cord

Abstract

Objective

Patients with cervical spondylotic myelopathy (CSM) have the same clinical symptoms that vary according to the degree of spinal cord compression and the cross-sectional cord shape. We used a three-dimensional finite element method (3D-FEM) to analyze the stress distributions of the spinal cord with neck extension under three cross-sectional cord shapes.

Methods

Experimental condition for the 3D-FEM spinal cord, ligamentum flavum, and anterior compression shape (central, lateral, and diffuse types) was established. To simulate neck extension, the spinal cord was extended by 20° and the ligamentum flavum was shifted distally according to movement of the cephalad lamina.

Results

The stress distribution in the spinal cord increased due to invagination of the ligamentum flavum into the neck extension. The range of stress distribution observed for the diffuse type was wider than for the central and lateral types. In addition, the stress distribution in the spinal cord was increased by the pincer movement of the ligamentum flavum and by the anterior compression of the spinal cord. The range of stress distribution observed for the diffuse type under antero-posterior compression was also wider than for the central and lateral types.

Conclusion

This simulation model showed that the clinical symptoms of CSM due to compression of the diffuse type may be stronger than for the central and lateral types. Therefore, careful follow-up is recommended for anterior compression of the spinal cord of diffuse type.     

脊髓型颈椎病患者颈脊髓与椎管匹配关系和脊髓致压因素的动态变化分析

【摘要】 目的：观察脊髓型颈椎病（cervical spondylotic myelopathy,CSM）患者颈脊髓与颈椎管匹配关系的动态变化,分析脊髓椎管匹配关系及脊髓致压因素与脊髓受压风险的关系。方法：收集2018年1月~2021年7月在我院行颈椎动态磁共振成像（dynamic magnetic resonance imaging,DMRI）检查的CSM患者的影像学资料,排除图像不清晰、屈伸角度不理想者,共纳入63例患者,其中男37例,女26例;年龄50~67岁（56.6±4.9岁）。在DMRI横断面T2像上测量颈椎前屈、中立、后伸体位下C3~C7椎间盘水平脊髓面积及硬膜囊面积,计算脊髓与硬膜囊面积的比值（即椎管占有率）;横断面T2像上测量椎间盘突出程度,矢状面T2像上测量黄韧带厚度;横断面T2像上观察脊髓的受压程度,采用改良Muhle分级标准进行脊髓受压分级;观察椎间盘的退变程度,应用Pfirrmann分级标准进行评估。将所有观察节段分为椎间盘突出组及椎间盘非突出组进行比较,分析椎间盘突出是否影响脊髓椎管的匹配关系及黄韧带厚度变化。结果：共测量252个颈椎节段,其中C3/4椎间盘非突出节段33个,突出节段30个;C4/5非突出节段21个,突出节段42个;C5/6非突出节段17个,突出节段46个;C6/7非突出节段27个, 突出节段36个。椎间盘非突出组与突出组都满足脊髓横断面积后伸位>中立位>前屈位,硬膜囊面积前屈位>中立位>后伸位,椎管占有率后伸位>中立位>前屈位,差异均有统计学意义（P＜0.05）。椎间盘突出组中立位与非突出组前屈位、中立位C5/6椎管占有率在C3～C7四个节段中最高,差异均有统计学意义（P＜0.05）。椎间盘突出程度后伸位>中立位>前屈位,脊髓受压分级后伸位>中立位>前屈位,黄韧带的厚度后伸位>中立位>前屈位,差异有统计学意义（P＜0.05）;椎间盘突出组的椎间盘退变等级高于非突出组,差异有统计学意义（P＜0.05）。椎间盘突出组黄韧带较厚,与非突出组比较差异有统计学意义（P＜0.05）。结论：DMRI可显示CSM患者颈脊髓与椎管匹配关系的动态变化,颈椎由前屈位向后伸位运动时椎管占有率增高,脊髓受压风险增大,其中C5/6节段所受影响最明显。     

皮导节段性脊髓诱发电位在脊髓型颈椎病中的应用

本文通过对１０只成兔、 ２０名神经功能正常看、 ３例椎管狭窄症不伴有脊髓功能障碍和 ３０例脊髓型颈椎病者经皮导出的皮导节段性脊髓诱发电位 （ｐｅｒｃｕｔａｎｅｏｕｓ ｓｅｇｍｅｎｔａｌ ｓｐｉｎａｌ ｃｏｒｄ ｅｖｏｋｅｄｐｏｔｅｎｔｉａｌ，ＰＳＳＣＥＰ）进行对比分析研究后，证实了从颈背侧中线皮下导出的Ｐ１、Ｎ１和Ｐ２波不仅能对脊髓型颈椎病做出脊髓功能定位诊断，而且对估计预后和制定正确手术方案都有一定参考和实用价值。     

Molecular biology of cervical myelopathy and spinal cord injury: role of oligodendrocyte apoptosis

BACKGROUND CONTEXT: Rational design of treatment strategies for cervical myelopathy and spinal cord injury requires a working knowledge of the molecular biology underlying these pathological processes. The cellular process of apoptosis is an important component of tissue and organ development as well as the natural response to disease and injury. Recent studies have convincingly demonstrated that apoptosis also plays a pivotal role in numerous pathological processes, contributing to the adverse effects of various diseases and traumatic conditions. A growing body of evidence has implicated apoptosis as a key determinant of the extent of neurological damage and dysfunction after acute spinal cord injury and in chronic cervical myelopathy. PURPOSE: To provide clinicians and research investigators interested in spinal cord injury and myelopathy with a practical and up-to-date basic science review of cellular apoptosis in the context of spinal cord pathology. STUDY DESIGN/SETTING: A review of recently published or presented data from molecular biological, animal model and human clinical studies. METHODS: A computer-based comprehensive review of the English-language scientific and medical literature was performed in order to identify relevant publications with emphasis given to more recent studies. RESULTS: Investigation into the role of apoptosis in spinal cord injury and myelopathy has drawn the interest of an increasing number of researchers and has yielded a substantial amount of new information. CONCLUSIONS: Apoptosis is a fundamental biological process that contributes to preservation of health as well as development of disease. There is now strong evidence to support a significant role for apoptosis in secondary injury mechanisms after acute spinal cord injury as well in the progressive neurological deficits observed in such conditions as spondylotic cervical myelopathy.     

不同载荷条件下颈脊髓过伸损伤的应力分布特征

目的 利用有限元法研究不同载荷条件下颈脊髓过伸损伤时脊髓内不同区域的应力分布特征. 方法 利用颈脊髓的三维有限元模型(此模型由8484个节点和14 297个单元组成),进入Ansys前处理器,设置边界条件和不同大小的载荷配置:第Ⅰ种载荷配置:后伸载荷0.0015 N,压缩载荷1N;第Ⅱ种载荷配置:后伸载荷0.0030 N,压缩载荷2 N;第Ⅲ种载荷配置:后伸载荷0.0045 N,压缩载荷3N;第Ⅳ种载荷配置:后伸载荷0.0060 N,压缩载荷4 N;第Ⅴ种载荷配置:后伸载荷0.0075 N,压缩载荷5N.模拟不同损伤情况,进入求解模块,进行过伸损伤负载模拟计算,最后进入Ansys后处理器,读取并分析颈脊髓横断面9个不同功能区域(颈脊髓白质前索、侧索外侧部、侧索内侧部、后索外侧部、后索内侧部、灰质前角、前角底部、后角尖和头部及后角颈部)的应力分析结果. 结果 颈脊髓损伤断面应力云图提示应力主要集中于灰质前角、后角和白质前索、侧索内侧和后索外侧内,并且其平均应力依次减小.随着施加载荷的增大,灰白质内各个部位的应力均明显增加,灰质前角内的应力增幅最大.灰质前角和白质侧索的应力增幅值比较差异有统计学意义(P<0.05),后角和白质前索分别与后索应力增幅值比较差异均有统计学意义(P<0.05),后角和白质前索应力增幅值比较差异无统计学意义(P>0.05). 结论 轻度颈脊髓过伸损伤主要造成白质前索和灰质前后角损伤,表现为以上肢为主的运动和感觉异常.随着损伤载荷加大,应力分布向相邻白质扩展,载荷加大后前角支配手内肌的神经元细胞较其他部位损伤更严重.     

Functional diagnosis using multimodal spinal cord evoked potentials in cervical myelopathy

The electrophysiological measurement of spinal cord evoked potentials (SCEPs) has been established as a tool for diagnosing the spinal level responsible for cervical myelopathy. Only a few studies, however, employed multimodal SCEPs for this purpose. The objective of this study was to investigate the correlation between multimodal SCEPs recorded during cervical laminoplasty and magnetic resonance imaging (MRI) abnormalities in 18 patients aged 70 years and older versus 32 patients less than 65 years of age. Both the SCEPs and MRIs showed higher incidences of multiple-level cord involvement in the older group than in the younger group. Discrepancies in the spinal levels involved between the SCEPs and the MRIs were found in 12 patients (67%) for the older group and 6 patients (19%) for the younger group. The accuracy of the MR images in localizing the lesion site was significantly lower in the older group than in the younger group, indicating that MR images tend to show clinically silent cord compression in elderly patients. Because spinal cord compression can appear without functional change in elderly patients, electrophysiological evaluations with intraoperative multimodal SCEP studies are a useful addition to MRI for understanding the pathology of myelopathy.     

无骨折脱位型颈髓损伤的临床研究进展

无骨折脱位型颈髓损伤是指没有骨折或脱位的颈部创伤所导致的急性颈脊髓损伤。通常多见于儿童,具体损伤机制至今仍不明了。X线、CT检查提示颈椎无骨折脱位,MRI检查有脊髓损伤的表现。临床表现多种多样,以脊髓中央型损伤综合征常见。临床治疗可分为保守治疗和手术治疗,如何选择合适的治疗方法仍存在争议。本文就无骨折脱位型颈髓损伤的病因、损伤机制、临床治疗等方面的研究进展作一综述。     

早期手术治疗急性颈脊髓损伤

目的 探讨早期手术治疗急性严重颈脊髓损伤的临床效果。方法 自1999～2002年对24例急性颈脊髓损伤的患者进行早期手术治疗，受伤到手术的平均时间为67h，手术方式包括颈椎前路手术、后路手术及前后路联合手术，对损伤的颈椎节段实施复位、减压、固定和融合。结果 22例获得12．38个月(平均18个月)的随访，除11例全瘫者中的2例无恢复外，其他病例均有不同程度的恢复，ASIA分级平均提高1．8个等级，无并发症发生。结论 对急性严重颈脊髓损伤，早期实施手术治疗可取得满意的治疗效果。     

外伤性无骨折脱位型颈髓损伤的误诊及对疗效的影响

目的 探讨外伤性无骨折脱位型颈脊髓损伤的误诊原因及其对疗效的影响. 方法 回顾1998年10月至2005年10月52例无骨折脱位型颈脊髓损伤患者病例资料,分析18例被漏诊或误诊患者其被漏诊或误诊的原因,并分别于入院时及治疗后随访时对脊髓损伤程度按ASIA标准分级进行评定与比较. 结果 所有患者获得6～67个月(平均29个月),患者入院时及治疗后随访时采用ASIA标准分级比较,34例无漏诊或误诊患者平均提高1.06级,18例被漏诊或误诊患者平均提高0.50级,采用等级资料Ridit分析,两组差异有统计学意义(u=2.0739,P=0.0381). 结论 无骨折脱位型颈脊髓损伤易被漏诊或误诊,早期确诊并合理治疗具有较好的疗效.     

颈椎骨折合并急性颈髓损伤的手术时机探讨

目的：探讨颈椎骨折合并急性颈髓损伤的手术时机。 方法：回顾性分析2000年1月~2011年1月我科治疗的颈髓损伤患者42例,其中急诊手术组（≤24h）18例,延期手术组（>24h）24例,对比分析手术前后神经功能变化、术后并发症和住院时间等临床资料,并进行统计学分析。 结果：急诊手术组感觉和运动功能改善明显,并发症发生率、重症监护时间和住院时间均低于延期手术组。 结论：颈椎骨折合并急性颈髓损伤的急诊手术减压是可行的,对神经功能的恢复有积极作用,并减少围手术期并发症。     

陈旧性颈髓损伤的外科治疗

目的：观察颈椎减压融合手术对陈旧性颈椎骨折脱位引起的颈脊髓或神经根损伤的治疗效果。方法：1999年1月～2003年12月手术治疗因颈椎骨折脱位合并不同程度颈脊髓损伤后1个月以上的患者58例，总结临床资料，比较手术前后感觉运动功能的改善程度。结果：平均随访27个月。术前ASIA分级A级的7例患者术后上肢有1～2个神经根功能改善者3例，下肢出现肌肉活动功能改善者2例：术前B级的11例患者术后8例上肢活动有改善，6例出现下肢功能改善；术前C级6例患者术后达D级3例，E级3例：术前D级34例患者术后达到E级24例，10例仍为D级。所有患者术后ASIA的感觉及运动评分较术前明显提高（P〈0．05）。结论：减压融合手术对陈旧性颈椎骨折脱位引起的颈脊髓损伤或神经根损伤仍是有效的治疗方法，脊髓功能的恢复与脊髓损伤程度有关。     

无骨折脱位型颈脊髓损伤治疗分析

目的探讨无骨折脱位型颈脊髓损伤保守与手术疗效差别以及手术时机的选择。方法 对1996年10月～2002年1月收治的无骨折脱位型颈脊髓损伤45例疗效进行探讨。结果 保守治疗病例脊髓功能恢复程度低。而手术治疗病例脊髓功能恢复程度较高，并县城越早手术脊髓功能改善率越高。手术均采用颈后路单开门椎管扩大成形术。结论 手术治疗效果显优于保守治疗，伤后1个月内手术效果最佳，伤后至手术时间越长，效果越差。     

Adult spinal cord injury with no radiographic bone lesion: analysis of nine consecutive patients

Background

Spinal cord injury with no radiographic bone lesion described as spinal cord injury without radiographic abnormality (SCIWORA) in childhood is less often reported in adults than in children. This study was undertaken to report our experience in the management of nine cases over 25 years.

Patients and methods

This was a retrospective study from 1985 to 2009 concerning nine adult patients who sustained spinal cord injury with no radiographic abnormality. The ratio among all cervical spine traumas for the same period was 2.21%. Magnetic resonance imaging (MRI) was performed in all the patients. The patients’ clinical status at the time of admission and discharge was evaluated using the Frankel's grading system. We report the results based on the clinical, epidemiologic and radiological findings and outcomes.

Results

The mean age of our population was 37.43 years, ranging from 18 to 60 years. All the patients were men. The main etiology was falls (5/9) followed by road traffic accidents (4/9). According to the Frankel's grading system, four patients (44.45%) were grade A, four were grade B (44.45%), and one was grade C (11.11%). On MRI, medullar lesions were: contusion, non-compressive cervical disc herniation, cervical spine stenosis, and two cases of normal cervical spine. Four patients were operated on via the posterior cervical spine approach (laminectomy, C3-C7 in three cases and C1-C3 in one case). The other five patients were treated orthopaedically for 6 to 8 weeks. Three patients (3/9), who were Frankel's grade B and C with no demonstrable injury on MRI, improved to Frankel a useful neurological grade (Frankel's grades D or E) at the time of discharge. One patient evaluated as Frankel's grade A died from cardiovascular disturbance.

Conclusion

Spinal cord injury with no radiographic abnormality accounted for 2.21% of cases of spinal cord injury in our series. MRI is the investigation of choice, having diagnostic and prognostic value because it demonstrates neural and extraneural injuries and helps to identify surgically correctable abnormalities.     

成人无骨折脱位型颈髓损伤的手术策略分析

目的回顾性分析不同手术策略治疗成人无骨折脱位型颈髓损伤,即无放射学异常的颈髓损伤(cervical spinal cord injury without radiographic abnormality,CSCIWORA)的疗效。方法对郑州市骨科医院2013年4月至2018年4月收治的69例成年CSCIWORA病人进行回顾性分析,收集病人术前、术后6个月的美国脊柱损伤协会(American Spinal Injury Association,ASIA)脊髓损伤分级,比较采用前路手术、后路手术和联合入路手术病人的ASIA分级,以及伤后7 d内手术与7 d后手术病人的ASIA分级情况。结果69例病人中,24例行颈椎前路手术,32例行后路手术,13例行前后路联合手术;术中出现脑脊液漏2例,行腰大池引流后均无感染。伤后7 d内完成手术的有51例,超过7 d完成的有18例。颈椎前路手术、后路手术和前后路联合手术病人之间的手术前后ASIA分级比较,差异均无统计学意义(P均>0.05)。伤后7 d内手术与7 d后手术病人术后6个月的ASIA分级比较,差异有统计学意义(Z=-2.460,P=0.014)。结论结合影像资料,制定个体化手术入路,把握手术时机(7 d内)解除压迫、重建颈椎稳定性可使颈髓损伤修复获益更多。     

仅累及上肢的急性中央颈脊髓损伤

介绍一种特殊类型的急性中央颈脊髓损伤。回顾分析24例仅仅表现为上肢运动与感觉损害症状的颈脊髓损伤患者，除1例行颈前路减压外均行保守治疗。结果有17例完全恢复正常，另7例遗留不同程度的手内在肌功能障碍。从受伤至运动功能恢复正常时间最短者为2周，最长者为4个月，平均恢复时间为2个月。而感觉功能恢复需4～6个月。作者认为其机制可能为颈脊髓前角细胞和后角细胞损害，非手术治疗多可取得满意疗效。     

无骨折脱位型颈髓损伤的临床研究

目的：探讨颈椎在无骨折脱位情况下出现颈髓损伤的临床机制。方法：观察２４例无骨折脱位型颈髓损伤，重点分析其影像学检查特点。结果：２７％病例合并椎管狭窄，８３％的病例存在椎间盘突出，不同程度压迫脊髓。结论：无骨折脱位型颈脊髓损伤机制中，存在外伤致颈椎间盘损伤，突出的间盘向后压迫损伤颈髓。颈椎间盘损伤受力机制为屈曲→压缩→过伸。颈椎管狭窄、椎间盘退变等是此类脊髓损伤的病理解剖基础     

脊髓型颈椎病患者术前脊髓MRI形态特征与手术预后的相关性研究

【摘要】 目的：提出改良脊髓压迫率（modified compression ratio,mCR）和脊髓旋转角（spinal cord rotation angle,SCRA）的概念,探讨脊髓型颈椎病（cervical spondylotic myelopathy,CSM）患者术前脊髓形态特征与术后脊髓功能恢复情况的关系。方法：回顾性分析2017年1月~2017年6月于我院行手术治疗的98例CSM患者,其中男性62例,女性37例,年龄38~73岁（53.8±10.7岁）。在患者术前轴位T2* MRI图像上测量脊髓在受压最严重层面（maximally compressed level,MCL）的脊髓压迫率（compression ratio,CR）,以椭圆拟合受压脊髓,脊髓在该椭圆短轴上的距离与椭圆长轴之比为mCR,该椭圆长轴与水平位置所成夹角为SCRA。以C2/3层面的相应形态指标为内参对MCL层面的CR、mCR和SCRA进行矫正。统计患者术前及术后3年的改良日本骨科协会（modified Japanese Orthopedic Association,mJOA）评分,并计算脊髓功能恢复率（recovery rate,RR）。以斯皮尔曼相关性分析及多因素分析形态指标（矫正CR、矫正mCR与矫正SCRA等）及临床参数（年龄、症状持续时间、术前mJOA评分等）与预后指标（术后3年mJOA评分与脊髓功能RR）的关系。结果：矫正CR为（58.31±16.71）%,矫正mCR为（49.11±16.17）%,矫正SCRA为5.09°（2.29°,10.61°）。症状持续时间12.0（4.3,36.0）个月,术前mJOA评分为13.46±1.69分,术后3年mJOA评分为16.00（14.50,16.50）分,脊髓功能RR为62.50%（33.33%,90.40%）。多因素分析显示,矫正SCRA为术后3年mJOA评分的独立预测因子[标准化系数（standardized coefficient,std.coef）=0.25,P=0.015],矫正mCR为脊髓功能RR的独立预测因子（std.coef=0.21,P=0.038）。矫正CR与术后3年mJOA评分及脊髓功能RR无显著相关性（P>0.05）。临床参数并非术后3年mJOA评分或脊髓功能RR的独立预测因子（P>0.05）。结论：矫正mCR、矫正SCRA可用于预测术后脊髓功能恢复情况,矫正SCRA与术后3年mJOA评分、矫正mCR与脊髓功能RR呈正相关。矫正CR与术后脊髓功能恢复情况无显著性相关。     

陈旧性颈椎过伸伤伴脊髓损伤的临床研究

目的 探讨陈旧性颈椎过伸伤伴脊髓损伤患者的临床特点及其转归.方法 回顾性分析30例陈旧性颈椎过伸伤患者的临床资料,从损伤到就诊时间为3个月～8年,根据就诊时间分为三组,第1组:3～6个月,17例;第2组:6～12个月,8例;第3组:12个月～8年,5例.分别在术前、术后3个月、术后1年进行JOA评分,观察神经功能的改善率,比较各组的恢复情况.26例行颈椎前路减压植骨内固定术,4例行颈椎后路减压植骨内固定术.结果 三组之间的患者例数构成存在显著性差异.30例均获随访,随访时间18～39个月,平均23个月.术后1年,第1组平均改善率为23.8%,第2组平均改善率为53.9%,第3组平均改善率为54.3%.术后3个月、术后1年,第1组和第2组、第1组和第3组的JOA评分存在显著性差异,第2组和第3组无显著性差异.结论 陈旧性颈椎过伸伤伴迟发性脊髓损伤的发生在时间上有逐渐减少的趋势,迟发性脊髓损伤发生越早的患者损伤越严重,手术后的恢复越差.     

无脊髓损伤颈椎骨折脱位的治疗分析

目的 探讨无脊髓损伤颈椎骨折脱位的治疗方法选择。方法 28例无脊髓损伤的颈椎骨折或骨折脱位，新鲜损伤26例，陈旧性损伤2例；其中23例手术治疗；5例保守治疗。结果 全部病例随访观察，症状均获得改善，17例完全恢复，7例残留手指麻木，4例颈椎旋转受限，颈椎椎间高度、生理曲度维持良好。结论 对于无脊髓损伤的稳定性上颈椎骨折脱位行牵引、制动、复位和固定，而不稳定性上颈椎骨折脱位应手术治疗；对于无脊髓损伤的下颈椎骨折脱位宜首选经前路手术治疗，前路手术除可达到减压、恢复颈椎椎间高度和生理曲度外，更重要的是可重建颈椎即刻稳定性，对防止继发性脊髓损伤有极其重要的作用。