三维有限元腰椎节段模型上模拟拨伸按压手法的生物力学分析

背景：应用计算机技术和有限元法对传统中医推拿手法进行研究,给传统的中医推拿手法研究注入了活力。 目的：分析手法治疗腰椎间盘突出症的机制,探求符合生物力学的治疗手法,明确手法治疗腰椎疾患的安全范围。 方法：选择成年无腰椎疾患的男性志愿者,年龄28岁,身高170 cm,体质量60 kg。采用CT对L3~S1进行扫描,利用ADINA5.0构件软件,并赋予不同组织不同的材料属性,建立腰椎有限元模型,设定腰椎水平位、后伸10°位、前屈30°位状态,加载拔伸按压载荷,观察腰椎间盘、髓核和纤维环的受力改变情况。 结果与结论：在拔伸按压状态下,腰椎前屈30°椎间盘组织的位移应变和应力变化最明显,提示在设定的条件下手法治疗腰椎疾患是安全的。     

正常下尺桡关节三维有限元模型的建立及验证

背景：国内外学者已应用有限元分析在前臂的桡骨骨折及其固定、尺骨骨折及其固定等方面进行了生物力学评价,但还未见应用该方法对下尺桡关节进行生物力学评价相关的文献报道。 目的：建立并验证下尺桡关节三维有限元模型,用于临床的生物力学研究。 方法：将1名健康男性志愿者右肱骨远端到腕关节中段的CT和MRI图像,导入Mimics10.01和ANSYS10.0中,建立下尺桡关节三维有限元模型,模拟体外生物力学试验,在横向拉伸、轴向压缩、旋前和旋后扭转4种工况下观测下尺桡关节各结构的应力分布,所得结果与文献报道的生物力学实测数据比较验证。 结果与结论：所构建的下尺桡关节有限元模型共有333 805个单元,508 384个节点,客观反映下尺桡关节真实解剖形态。所建模型在横向拉伸、轴向压缩、旋前和旋后扭转4种工况下,理论分析结果与生物力学实测数据一致。证实所建的下尺桡关节有限元模型真实性较高,可用于生物力学分析实验。     

人工椎间盘置换对腰椎小关节应力影响的三维有限元分析

背景：近年来随着对脊柱生物力学研究的深入,人工椎间盘被认为是治疗腰椎退行性变较理想的方法,但目前对人工腰椎间盘的生物力学研究还非常有限。 目的：建立腰椎运动节段人工椎间盘置换的三维有限元模型并进行生物力学分析,观察人工椎间盘置换对腰椎小关节应力的影响。 方法：在已建立的正常腰椎运动节段三维有限元模型的基础上去除L4~5椎间盘、上下终板的有限元单元,加入SB-Chaite Ⅲ型人工椎间盘的有限元模型,保留L4~5椎间隙的纤维环及相关韧带,形成L4~5运动节段人工椎间盘置换的三维有限元模型。对三维有限元模型在垂直压缩、前屈、后伸、侧弯等不同载荷下进行生物力学分析,记录小关节的应力,并与正常运动节段三维有限元模型相应部位的应力进行对比。 结果与结论：生物力学分析结果显示,人工椎间盘置换后：①垂直压缩时上下椎体、双侧小关节内应力与正常节段相比差异无显著性意义(P > 0.01)。②前屈、后伸时上下椎体前、后方及双侧小关节内应力与正常节段相比差异无显著性意义(P > 0.01)。③侧弯时上下椎体左右两侧及双侧小关节内应力与正常节段相比差异无显著性意义(P > 0.01)。提示人工腰椎间盘置换后小关节应力可保持在正常运动节段的水平,人工腰椎间盘置换可以达到腰椎生物力学性能重建的目的。     

按摩治疗82例腕管综合征的疗效观察

腕管综合征是一种临床常见病之一。临床以患手桡侧三个半手指(拇、食、中、1/2无名指)有异常感觉:麻木、刺痛。一般夜间较差。祖国医学认为本病由于急性损伤或慢性劳损,使血淤经络,及寒湿淫筋,风邪袭肌致气血流通受限而引起。1临床资料本组共计观察治疗82例,女57例,男25例。年龄最大81岁,最小28岁。病程最长2年半,最短3个月。2治疗2.1治则舒筋通络,活血化瘀。2.2手法一指禅推、按、揉、摇、擦。3操作3.1患者正前坐将患手伸出,掌心朝上置放桌上,医者用拇指依次点按:曲泽、内关、大陵、鱼际穴各1min。3.2用一指禅推法在前臂至手沿手厥阴心包经…     

腰椎斜扳手法时椎间盘的有限元分析

背景：利用计算机技术和有限元法分析法研究中医传统的脊柱推拿手法，来解释手法的作用机制、适应证和禁忌证，可为临床上常用的腰椎斜扳手法提供了客观的、科学的理论依据。 目的：应用有限元法了解进行斜扳手法时腰椎间盘的内在应力及位移分布的特点。 方法：使用正常腰椎CT片，以Mimics软件系统逐层重建，建立L4~5三维有限元模型。根据手法原理，将腰椎斜扳手法进行分解，把各项力学参数代入三维有限元模型进行计算分析。即时显示手法作用时腰椎间盘的位移和内在应力的变化。 结果与结论：椎间盘的应力远小于后部结构；从椎间盘中心到右侧有一个向后的扭转矢量，使椎间盘产生变形。结果证明腰椎斜扳手法对椎间盘是安全的，并且在椎间盘突出的对侧进行手法操作更为合理；腰椎椎管狭窄的患者不宜使用腰椎斜扳手法。     

一个新枕寰枢有限元模型的建立与生物力学分析

目的 建立一个新型枕寰枢复合体有限元模型并对其进行生物力学分析.方法 采集CT断层资料,应用Mimics软件完成枕寰枢的三维重建并获取点云数据,辅助以逆向工程完成骨性结构的曲面重构;采用Ture Grid软件建立包括关节软骨在内的全六面体有限元网格模型,建立模拟韧带的弹簧单元;在0.3 Nm和1.5 Nm外载荷下进行了前屈、后伸、侧屈和轴向旋转四种生理运动的生物力学分析及有效性验证.结果 该枕寰枢模型能对正常情况下生物力学特性如运动学、韧带应变、关节应力等进行预测.结论 枕寰枢有限元模型对枕颈交界区生物力学的改变及其稳定性的影响可以进行有效的、可重复的仿真分析,具有较高的实用性和临床参考价值.     

过伸复位治疗胸腰椎单纯压缩性骨折的有限元分析

背景：过伸复位被中医骨伤科临床广泛用于治疗胸腰椎单纯压缩性骨折,其生物力学机制研究尚显不足。 目的：应用有限元分析方法探讨了复位过程中各结构的力学特性以及整体的应力特点。 方法：依据1例T12椎体单纯压缩性骨折患者的210层Dicom3.0标准的CT图片建立T12椎体单纯压缩性骨折的有限元模型,在对建立的模型的有效性进行验证后模拟过伸复位手法,约束L2下端所有面,给T11椎体上端一个纵向牵引力,分别于T11,T12,L1椎骨棘突顶点给予一个方向垂直朝向椎体、大小为3.0 cm的位移。程序运算后读取压缩椎骨外形改变和应力分布。 结果与结论：建立了几何外型逼真、生物力学特性全面的胸腰段椎体压缩性骨折三维有限元模型,复位手法作用后压缩的椎骨表现出明显的过伸,在复位过程中表现的复位机制与传统的生物力学实验相同。利用有限元分析法研究传统手法的作用机制具有实验结果可靠、显示结果直观、节约资源以及手法模拟精确等优点,可广泛应用于骨折手法复位机制的研究。     

建立正常人C2~7的三维有限元模型

背景：随着计算机技术的发展,颈椎生物力学研究不再局限于动物或人体尸体实验,计算机模型可以进行更准确的生物力学研究。 目的：在已有研究的基础上,建立人体C2~7三维有限元模型,以期为颈椎前路分节段减压融合的生物力学研究提供参考数据。 方法：选择1名28岁健康男性志愿者为观察对象,无明显的颈椎病史,扫描前先拍摄颈椎正侧位、斜位、过伸过屈位X射线片以排除颈椎病变。首先根据志愿者CT扫描图片,采用计算机辅助设计数据处理技术,输入相关的材料特性,构建C2~7三维有限元模型。模型重建采用先进的Geomagics系统,可以准确模拟颈椎结构,有限元部分则采用广泛使用的ANSYS系统。其次在1.8 N•m作用力下,观察节段运动与力-位移反应,并与国外的实验结果对比,在前屈、后伸、侧弯和旋转等4种工况(载荷状态)下对模型进行验证。 结果与结论：整个模型包括C2~7六个椎体、C2/3~6/7五个椎间盘以及后部结构与主要韧带,共有23 348个节点和215 749个单元。在模拟外力的作用下,模型前屈、后伸、侧弯和旋转工况下的颈椎活动度与以往实验模型结果数据基本吻合。提示所建立的颈椎有限元模型可以模拟颈椎生物力学实验,进行生物力学分析。     

骶髂关节脱位两种内固定的三维有限元分析

背景：有限元法能对复杂的结构、形态、载荷和材料力学性能进行应力分析比较,已经是骨科生物力学研究中的重要手段。 目的: 旨在建立骨盆骶髂关节（单侧）脱位模型,比较两种内固定治疗后的生物力学稳定性,为临床骶髂关节损伤的治疗提供生物力学依据。 设计、时间及地点：三维有限元分析,单一样本观察。于2007-01/03在南方医科大学生物力学实验室完成。 方法: 在正常的骨盆三维有限元模型的基础上,截断骶髂关节间的骶髂前后韧带(包含骶髂骨间韧带),以及骶结节韧带和骶棘韧带等盆底韧带,造成骶髂关节脱位。分别在两种固定方法的模型上,加载后进行非线性有限元分析。 主要观察指标：计算该加载方式下的骨盆的应力、应变及位移的分布情况。 结果: 建立了高精度骨盆骶髂关节脱位两种内固定的三维有限元模型。通过应力应变云图分析与比较后发现,采用骶髂关节拉力螺钉内固定相对于前路钢板内固定移位的总位移小,应力分布均匀,无明显高度集中现象,固定强度更大,固定后的骨盆更稳定。 结论: 利用有限元方法分析骨盆骶髂关节脱位两种内固定生物力学稳定性,具有较高真实性、精确度和可重复性,结果与其他生物力学实验结果相一致。能满足临床骨盆损伤研究的需要。 关键词:骶髂关节脱位;重建钢板;拉力螺钉;有限元分析     

全颈椎有限元模型的建立与验证*

背景：有限元分析作为数值计算中的一种离散化方法,具有实验时间短、费用少、对身体无任何破坏、力学性能测试全面及可重复实验等突出优点。以往研究多将其集中应用于腰椎模型,由于颈椎解剖结构及损伤机制复杂,稳定性差等原因,颈椎有限元模型研究不多,并且研究只局限于单椎体和运动节段。 目的：建立更为真实、有效的全颈椎三维有限元模型,用于临床生物力学研究。 方法：对1名既往无颈椎病史健康男性志愿者的颈椎进行CT扫描成像,应用CAD造型软件Solid-Works2003、HyperMesh软件和ANSYS11.0软件,采用四面体网格划分方法,对颈椎周围组织赋予不同的材料特性,引入接触理论和非线性结构计算方法,建立全颈椎有限元模型。在所建模型上加载模拟脊柱的前屈、后伸、左右侧屈、左右旋转6种工况下的生理活动,并与生物力学实验数据进行对比。 结果与结论：所建模型共有97 705个节点,372 896个单元。所建立模型在前屈/后伸、左右侧弯、左右旋转6种方向的运动范围,理论分析结果与生物力学实测数据高度一致。证实建立的全颈椎三维有限元模型细腻有效,具有良好的生物逼真度,可应用于临床生物力学分析。 关键词：颈椎;生物力学;有限元;三维模型;数字化骨科技术     

Epilepsy and anomalies of neuronal migration: MRI and clinical aspects

Neuronal migration disorders are the result of disturbed brain development. In such disorders, neurons are abnormally located. In diagnosing these conditions, magnetic resonance imaging is superior to any other imaging technique. This enables us to improve our knowledge of the clinical correlates of neuronal migration. With reference to migrational disorder, a retrospective study of all 303 patients with epileptic seizures referred for magnetic resonance imaging during a 3-year period was performed, 13 patients (aged 12-41, mean age 27) were identified. They represent 4.3% of the entire study group. Of the patients with known epilepsy, 6.7% and of the mentally retarded, 13.7% had migrational disorders. Four patients had schizencephaly as the dominant finding, one was classified as hemimegalencephaly, 2 had isolated heterotopias, and 6 had localized pachy- and/or poly-microgyria. The clinical pictures are complex. Ectopias of grey matter are recognised foci of epilepsy, but from an epileptological and a clinical viewpoint little attention has been given to these disorders. The present study shows that malmigration is not rare in epilepsy patients, especially not in the mentally retarded.     

Hepatic Considerations in the Use of Antiepileptic Drugs

Summary: Virtually all of the major antiepileptic drugs (AEDs) can cause hepatotoxicity, although fatal hepatic reactions are rare. The mechanisms, incidences, and risk profiles for such reactions differ from drug to drug. With carbamazepine and phenytoin, hepatotoxicity may be due to drug hypersensitivity. Although the profiles of patients at risk have not been well-defined for these two antiepileptic drugs, it would appear from reports in the literature that older adolescents and adults are at higher risk than children of developing serious or fatal hepatotoxicity. Once hepatotoxicity develops, mortality rates are 10–38% with phenytoin and 25% for carbamazepine. The risk profile for valproate fatal hepatotoxicity has been more clearly defined. Those at primary risk of fatal hepatic dysfunction are children under the age of 2 years who are receiving multiple anticonvulsants and also have significant medical problems in addition to severe epilepsy. The risk is considerably lower for patients over the age of 2 years on valproate monotherapy. In contrast to the risk profile with other AEDs, adults receiving valproate as monotherapy have the lowest risk of hepatotoxicity. Fatal hepatic dysfunction coincident with valproate may be the result of aberrant drug metabolism. Concomitant use of AEDs that induce microsomal P450 enzymes (e.g., phenytoin and phenobarbital) may enhance the production of a toxic metabolite, and hence the greater risk of hepatotoxicity with polypharmacy.     

Vascular Malformations and Epilepsy: Clinical Considerations and Basic Mechanisms

Summary: Vascular malformations (VMs) are associated with epilepsy. The natural history of the various VMs, clinical presentation, and tendency to provoke epilepsy determine treatment strategies. Investigations have probed the mechanisms of epileptogenesis associated with these lesions. Electrophysiologic changes are associated with epileptogenic cortex adjacent to VMs. Putative pathophysiologic mechanisms of epileptogenesis include neuronal cell loss, glial proliferation and abnormal glial physiology, altered neurotransmitter levels, free radical formation, and aberrant second messenger physiology.     

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES.     

Carbamazepine Efficacy and Utilization in Children

Summary: Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmacokinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.     

Neonatal Seizures: Problems in Diagnosis and Classification

Summary: The clinical identification of neonatal seizures is critical for the recognition of brain dysfunction; however, diagnosis is often difficult because of the poorly organized and varied nature of these behaviors. Current classification systems are limited in their ability to communicate motor, autonomic, and electroencephalo-graphic features of seizures precisely and to provide a basis for uniform effective diagnosis, therapy, and determination of prognosis. Recent investigations of neonates, utilizing bedside electroencephalographic/polygraphic/ video monitoring techniques, have provided the basis for improved diagnosis and classification of seizures in the newborn. These studies have demonstrated that not all clinical phenomena currently considered to be seizures require electrocortical epileptiform activity for their initiation or elaboration. In addition, the specific clinical character of the phenomena considered to be seizures, the clinical state of the infant, and the character of the EEG indicate the probable pathophysiological mechanisms involved and suggest probable etiologies, prognosis, and therapy. Similarities between animal models that demonstrate reflex physiology and neonates with motor automatisms and tonic posturing suggest that these clinical behaviors may not be epileptic in origin but, rather, primitive movements of progression and posture mediated by brainstem mechanisms. Although not all clinical behaviors currently considered to be neonatal seizures may have similar pathophysiological mechanisms, they are clinically significant because they all indicate brain dysfunction.     

Valproate Monotherapy in the Management of Generalized and Partial Seizures

Summary: For decades, therapeutic tradition has promoted the concept of polypharmacy in the management of epilepsy. In recent years, however, studies have shown that, for most patients, monotherapy can provide comparable or better seizure control than administration of multiple anticonvulsants, while diminishing the potential for adverse reactions, drug interactions, and poor compliance. Valproate is an important monotherapeutic agent that is highly effective in the control of idiopathic primary and secondarily generalized epilepsies, and partial seizures that do not generalize. Comparative studies have found that valproate is at least as effective as phenytoin and carbamazepine in the treatment of generalized and partial seizures. Given the similar efficacy, other factors such as pharmacokinetics and side effects may therefore determine anticonvulsant selection for monotherapy.     

Un nouveau cadre conceptuel de travail pour la psychiatrie

In an attempt to place psychiatric thinking and the training of future psychiatrists more centrally into the context of modern biology, the author outlines the beginnings of a new intellectual framework for psychiatry that derives from current biological thinking about the relationship of mind to brain. The purpose of this framework is twofold. First, it is designed to emphasize that the professional requirements for future psychiatrists will demand a greater knowledge of the structure and functioning of the brain than is currently available in most training programs. Second, it is designed to illustrate that the unique domain which psychiatry occupies within academic medicine, the analysis of the interaction between social and biological determinants of behavior, can best be studied by also having a full understanding of the biological components of behavior.