A one-dimensional model of the spinal cerebrospinal-fluid compartment

Modeling of the cerebrospinal fluid (CSF) system in the spine is strongly motivated by the need to understand the origins of pathological conditions such as the emergence and growth of fluid-filled cysts in the spinal cord. In this study, a one-dimensional (1D) approximation for the flow in elastic conduits was used to formulate a model of the spinal CSF compartment. The modeling was based around a coaxial geometry in which the inner elastic cylinder represented the spinal cord, middle elastic tube represented the dura, and the outermost tube represented the vertebral column. The fluid-filled annuli between the cord and dura, and the dura and vertebral column, represented the subarachnoid and epidural spaces, respectively. The system of governing equations was constructed by applying a 1D form of mass and momentum conservation to all segments of the model. The developed 1D model was used to simulate CSF pulse excited by pressure disturbances in the subarachnoid and epidural spaces. The results were compared to those obtained from an equivalent two-dimensional finite element (FE) model which was implemented using a commercial software package. The analysis of linearized governing equations revealed the existence of three types of waves, of which the two slower waves can be clearly related to the wave modes identified in previous similar studies. The third, much faster, wave emanates directly from the vertebral column and has little effect on the deformation of the spinal cord. The results obtained from the 1D model and its FE counterpart were found to be in good general agreement even when sharp spatial gradients of the spinal cord stiffness were included; both models predicted large radial displacements of the cord at the location of an initial cyst. This study suggests that 1D modeling, which is computationally inexpensive and amenable to coupling with the models of the cranial CSF system, should be a useful approach for the analysis of some aspects of the CSF dynamics in the spine. The simulation of the CSF pulse excited by a pressure disturbance in the epidural space, points to the possibility that regions of the spinal cord with abnormally low stiffness may be prone to experiencing large strains due to coughing and sneezing.     

Radiographic, histologic, and cytologic lesions associated with mutations in the fitness1(4226SB) locus of mice.

BACKGROUND AND PURPOSE: Previous investigation of fitness1(4226SB) mice revealed growth retardation and microcytic, hypochromic anemia with functional iron deficiency. Serum biochemical analysis suggested protein-losing enteropathy and liver dysfunction. METHODS: Radiography was done to assess lumbar bone lesions in mice hemizygous for fitness1 (fit1) [c fit1(4226SB/Df(c Mod2 sh1)26DVT] and age-matched sibling controls [c(ch)+/c(ch)+] at 40 or 60 days of age. Macroscopic and microscopic lesions were evaluated at necropsy. Bone marrow was examined cytologically to evaluate hematopoietic lesions. RESULTS: Mice hemizygous for fit1 had radiographically evident lumbar vertebral abnormalities, including various degrees of vertebral body fusion, with loss of intervertebral disk spaces and mild, generalized osteopenia. All mutant mice had scoliosis. Several mutant mice had lordosis and/or kyphosis of variable severity and mild subluxation at the lumbosacral junction. Marked splenomegaly and mild cardiomegaly were evident, and bone marrow color ranged from normal to slightly pale. The spleen had marked extramedullary hematopoiesis; lumbar vertebrae contained microscopic lesions that corresponded to the radiographic lesions. Cytologic examination of bone marrow revealed normocellular to hypocellular status, with mild to moderate erythroid hypoplasia characterized by mild increase in the myeloid-to-erythroid cell ratio, decreased percentage of erythroid precursors, and slight increase in percentage of myeloid precursor cells. CONCLUSIONS: Mutations in fit1 directly or indirectly cause alteration(s) in blood, organs of hematopoiesis (bone marrow, spleen, and liver), heart, and vertebral column, and suggest that this mouse may be a good model for study of scoliosis and relationships between iron metabolism and bone growth.     

Morphometric variations of the lumbar vertebrae between Chinese and Indian adults.

A morphometric study of the lumbar vertebrae of 126 adult skeletons, 90 Chinese and 36 Indian, of both sexes without marginal osteophytes were performed. In each lumbar vertebra, the cephalad and caudad midsagittal diameters, the interpedicular diameter of the spinal canal as well as the midsagittal and transverse diameters and the height of the vertebral body were measured. The results showed that the midsagittal and transverse diameters, the heights of the lumbar vertebral bodies and the interpedicular diameters of the lumbar spinal canals increased progressively from L1 to L5, while the midsagittal diameters of the lumbar spinal canals decreased progressively from L1 to L5 in both Chinese and Indian adult skeletons. The lowest mean values of the cephalad and caudad midsagittal and the interpedicular diameters of the spinal canals in Chinese were found to be 5.04 +/- 0.15 mm at L5, 4.67 +/- 0.09 mm at L5 and 25.92 +/- 0.20 mm at L2, respectively, while in Indians they were found to be 4.54 +/- 0.18 mm at L5, 4.25 +/- 0.10 mm at L5 and 25.42 +/- 0.22 mm at L1, respectively. In addition, the mean diameters of the spinal canal and the vertebral body (except the height of the vertebral body) were significantly greater in the Chinese than in the Indian skeletons. The above findings indicate that the mean diameters of both the lumbar spinal canal and the vertebral body vary greatly between Chinese and Indian adults, i.e. there are no mean values of the vertebral dimensions that are valid for all populations.(ABSTRACT TRUNCATED AT 250 WORDS)     

经皮椎板间内镜与椎板小开窗术治疗腰椎间盘突出症临床疗效比较

目的：分析和比较椎板间内镜与椎板小开窗术治疗腰椎间盘突出症的临床疗效和安全性指标。方法：使用回顾性分析的方法 对2012-2014 年共计126 例在我科行椎板间内镜手术或椎板小开窗手术的腰椎间盘突出患者进行分析和比较。通过纳入和排除 标准的筛选,经皮椎板间内镜组纳入48例,椎板小开窗组纳入78 例。结合详实的术后随访,对两组患者在花费,住院时间等一般 性指标,疼痛指标,功能指标,并发症等数据进行分析和比较。结果：两组患者在术后均取得明显的治疗疗效,在疼痛、功能等指标 中都有明显的改善。但两组之间并无明显统计学差异(P>0.05)。而椎板间内镜组在住院时间,出血量,切口长度及并发症等方面明 显的优于小开窗组,具有统计学意义(P<0.05)。结论：经皮椎板间内镜手术作为一种脊柱微创手术,治疗效果确切,安全性好,能体 现微创的优势,可作为椎间孔镜技术在治疗椎间盘突出症的有益补充,在临床中进一步的开展和推广。     

Silicon compatible with the height of human vertebral column

In the study on human vertebral composites, silicon was found to be related to the height of the vertebral column. The element ratio of silicon to calcium in the lumbar vertebra was twice that of the lowest one in the cervical vertebra. The element ratio gradually increased from approx 0.5 at the cervical vertebra to approx 1.0 at the lumbar one. Silicon is preserved catastropically much more in the lower height of the backbone in contrast with the calcium amount, and the ratio to sulfur appears to be unchanged. This suggests that silicon is compatible with the biokinetics of the vertebral bone structure of calcium.     

Scaling of lumbar vertebrae in anthropoids and implications for evolution of the hominoid axial skeleton

We investigated allometric relationships between vertebral centrum cranial surface areas and body weight and skeletal lumbar length in extant platyrrhine and cercopithecid species. Platyrrhines have smaller lumbar vertebral centra regarding the cranial surface area relative to their body weight than extant catarrhines. However, the stress to the spine of quadrupeds is not only influenced by the body weight but also its length, which contributes to the amount of bending moment. Our results indicated that platyrrhines and cercopithecids have similar lumbar vertebral centrum surface areas when they are scaled on the product of the body weight and skeletal lumbar length. Platyrrhines generally tend to have relatively short lumbar columns for a given body weight. As a result of this tendency, their vertebral centra appear relatively small if only body weight is taken into account. The centrum surface area is rather constant relative to the product of the body weight and skeletal lumbar length within platyrrhines or cercopithecids, despite the fact that skeletal lumbar length is in itself rather variable relative to body weight. This result indicates that the vertebral centrum articular area, the lumbar column length and the body weight are strongly correlated with each other and that such relationships are similar between platyrrhines and cercopithecids. These relationships were observed using both the zygapophyseal and rib definitions of the lumbar vertebrae. However, they were more clearly observed when the zygapophyseal definition was adopted. It appeared that lumbar vertebrae of Proconsul nyanzae (KNM−MW 13142) had distinctively smaller surface areas relative to its body weight and lumbar length than for platyrrhines and cercopithecids, differing from extant hominoids, which have comparatively larger lumbar vertebrae. In the case of Morotopithecus, the lumbar vertebral surface area seems to be as large as in extant platyrrhines and cercopithecids if it had a reduced number of lumbar vertebrae. It is uncertain whether its lumbar vertebral surface area was as large as in extant hominoids. Electronic Publication     

The arterial supply of the thoracic and lumbar spine in newborns

The major arteries supplying the vertebral column are definite. The branching arteries of these trunks are variable. The posterior intercostal arteries and the lumbar arteries have an ascending, descending or horizontal course. In accordance with the literature, we found large, arched anastomoses between the rami ascendentes and the rami descendentes arising from the rami canalis vertebralis anteriores on the dorsal plane of the vertebral bodies. There are also nearly horizontal junctions between the rr. ascendentes of both sides. We found junctions on the front of the thoracolumbar vertebral column at the end of the arteries. On the dorsal plane of the vertebral body 2 arteriae centrales posteriores originate from the rr. ascendentes. They run to the centre of the vertebral body. On the ventrolateral plane of the vertebral body 2 or 3 aa. centrales anteriores can be found. These 4 or 5 arteries join in the middle of the vertebral body. The blood supply of the thoracal and lumbar vertebral bodies does not differ essentially. Vessels come especially from lateral in the intervertebral disc. We suggest to name such a vessel ramus disci intervertebralis. The posterior longitudinal ligament is mainly supplied by the junction between the rr. ascendentes of both sides and the anterior longitudinal ligament by the aa. nutriciae in the thoracal and the lumbar area.     

Extra- and intraorganic blood channel of the rabbit lumbar vertebrae in health and after cutting the segmentary arteries and veins

Extra- and intraorganic blood bed of the lumbar vertebrae has been investigated by means of the cast method and vital injection of the vessels with Indian ink-gelatin mixture and subsequent serial translucent preparations. Existence of constant topographo-anatomical relations has been stated between the segmentary arteries and veins with the lumbar vertebrae. Peculiarities in spatial organization of the microcirculatory bed have been revealed in different zones of the vertebral body, as well as peculiarity of blood supply of the epiphyseal osseous marginal plate. Topography and localization of changes in the intraorganic vertebral blood bed have been studied under conditions of bilateral crossing of the segmentary vascular fasciculi at the level of one, two and three vertebrae. Compensatory resources of the vertebral column blood bed are discussed, when large extra-organic trunks in the lumbar part are damaged.     

Functional aspects of strepsirrhine lumbar vertebral bodies and spinous processes

The relationship between form and function in the lumbar vertebral column has been well documented among platyrrhines and especially catarrhines, while functional studies of postcranial morphology among strepsirrhines have concentrated predominantly on the limbs. This morphometric study investigates biomechanically relevant attributes of the lumbar vertebral morphology of 20 species of extant strepsirrhines. With this extensive sample, our goal is to address the influence of positional behavior on lumbar vertebral form while also assessing the effects of body size and phylogenetic history. The results reveal distinctions in lumbar vertebral morphology among strepsirrhines in functional association with their habitual postures and primary locomotor behaviors. In general, strepsirrhines that emphasize pronograde posture and quadrupedal locomotion combined with leaping (from a pronograde position) have the relatively longest lumbar regions and lumbar vertebral bodies, features promoting sagittal spinal flexibility. Indrids and galagonids that rely primarily on vertical clinging and leaping with orthograde posture share a relatively short (i.e., stable and resistant to bending) lumbar region, although the length of individual lumbar vertebral bodies varies phylogenetically and possibly allometrically. The other two vertical clingers and leapers, Hapalemur and Lepilemur, more closely resemble the pronograde, quadrupedal taxa. The specialized, suspensory lorids have relatively short lumbar regions as well, but the lengths of their lumbar regions are influenced by body size, and Arctocebus has dramatically longer vertebral bodies than do the other lorids. Lumbar morphology among galagonids appears to reflect a strong phylogenetic signal superimposed on a functional one. In general, relative length of the spinous processes follows a positively allometric trend, although lorids (especially the larger-bodied forms) have relatively short spinous processes for their body size, in accordance with their positional repertoire. The results of the study broaden our understanding of postcranial adaptation in primates, while providing an extensive comparative database for interpreting vertebral morphology in fossil primates.     

Developmental characteristics of the human lumbar spinal column at various periods of ontogeny

Regularities in development and differentiation of vertebrae have been investigated according to ageing. The data concerning the size of the vertebral canal at the level of the lumbar vertebral bodies and intervertebral discs, intensity of increase of these dimensions in various age periods, the character of spatial relations of sizes and form of the canal has been analysed. The transversal section area of the canal and the body in the corresponding segment varies between 1:3 and 1:5.5. By means of x-ray osteophotometry the mineralization degree of the lumbar vertebral bodies has been determined in men of various age. An important fact has been stated on a close connection between mineral saturation in juvenile and first mature ages with induces of general strength.     

椎体加椎间植骨融合术在腰椎爆裂性骨折患者中的应用效果与安全性探究

目的:探讨椎体加椎间植骨融合术在治疗腰椎爆裂性骨折患者中的临床效果及安全性。方法:选取2016年12月～2017年10月我院骨科收治的腰椎爆裂性骨折患者90例,按照手术方式将患者分成研究组和对照组,每组45例。研究组给予后路内固定术联合椎体加椎间植骨术治疗,对照组给予后路内固定术联合后外侧植骨术治疗。比较两组患者的手术时间、手术出血量以及术后3个月和12个月的椎体Cobb角、患者术后骨折愈合情况、内固定有效情况。结果:研究组手术时间、术中出血量、术后3个月和12个月椎体Cobb角明显短于或低于对照组,但骨折愈合率、内固定有效率显著高于对照组,组间差异均有统计学意义(P0.05)。结论:椎体加椎间植骨融合术治疗腰椎爆裂性骨折的临床综合效果显著优于后路内固定术联合后外侧植骨术治疗,且安全性较好。     

Cortical potentials evoked by epidural stimulation of the cervical and thoracic spinal cord in man

Scalp somatosensory evoked potentials (SEPs) were recorded after electrical stimulation of the spinal cord in humans. Stimulating electrodes were placed at different vertebral levels of the epidural space over the midline of the posterior aspect of the spinal cord. The wave form of the response differed according to the level of the stimulating epidural electrodes. Cervical stimulation elicited an SEP very similar to that produced by stimulation of upper extremity nerves, e.g., bilateral median nerve SEP, but with a shorter latency. Epidural stimulation of the lower thoracic cord elicited an SEP similar to that produced by stimulation of lower extremity nerves. The results of upper thoracic stimulation appeared as a mixed upper and lower extremity type of SEP. The overall amplitudes of SEPs elicited by the epidural stimulation were higher than SEPs elicited by peripheral nerve stimulation. In 4 patients the CV along the spinal cord was calculated from the difference in latencies of the cortical responses to stimulation at two different vertebral levels. The CVs were in the range of 45–65 m/sec. The method was shown to be promising for future study of spinal cord dysfunctions.     

Functional proportions of primate lumbar vertebral bodies

The comparison of certain proportions of lumbar vertebral bodies and of the lumbar column as a whole between a range of primate and non-primate mammals suggests that the relatively high robusticity of the lumbar column in primates may be related to habitual trunkal erectness. A decrease in the total number of lumbar vertebrae and high robusticity of individual vertebrae may be associated with large body size and positional habits in which trunkal erectness is particularly important. In some groups of primates proportions may relate to particular back movements occurring during quadrupedal progression or to positional suspension. Allometric regressions suggest that resistance to bending may be as important a function of lumbar vertebral bodies as resistance to compression. The proportions of the immediately pre-sacral lumbar vertebral bodies help to produce the normal human lumbar lordosis, but other factors must also be involved in the formation of the lordosis.     

Vertebrae numbers of the early hominid lumbar spine

General doctrine holds that early hominids possessed a long lumbar spine with six segments. This is mainly based on Robinson's (1972) interpretation of a single partial Australopithecus africanus skeleton, Sts 14, from Sterkfontein, South Africa. As its sixth last presacral vertebra exhibits both thoracic and lumbar characteristics, current definitions of lumbar vertebrae and lumbar ribs are discussed in the present study. A re-analysis of its entire preserved vertebral column and comparison with Stw 431, another partial A. africanus skeleton from Sterkfontein, and the Homo erectus skeleton KNM-WT 15000 from Nariokotome, Kenya, did not provide strong evidence for the presence of six lumbar vertebrae in either of these early hominids. Thus, in Sts 14 the sixth last presacral vertebra has on one side a movable rib. In Stw 431, the corresponding vertebra shows indications for a rib facet. In KNM-WT, 15000 the same element is very fragmentary, but the neighbouring vertebrae do not support the view that it is L1. Although in all three fossils the transitional vertebra at which the articular facets change orientation seems to be at Th11, this is equal to a large percentage of modern humans. Indeed, a modal number of five lumbar vertebrae, as in modern humans, is more compatible with evolutionary principles. For example, six lumbar vertebrae would require repetitive shortening and lengthening not only of the lumbar, but also of the entire precaudal spine. Furthermore, six lumbar vertebrae are claimed to be biomechanically advantageous for early hominid bipedalism, yet an explanation is lacking as to why the lumbar region should have shortened in later humans. All this raises doubts about previous conclusions for the presence of six lumbar vertebrae in early hominids. The most parsimonious explanation is that they did not differ from modern humans in the segmentation of the vertebral column.     

The arterial supply of the cervical vertebral body in newborns

The cervical vertebral column is mainly supplied by both vertebral arteries. A regular ladder pattern of arteries is on the dorsal plane as well as on the ventral plane of the cervical vertebral bodies, opposite to the thoracal and the lumbar area of the vertebral column with only a dorsal ladder pattern of arteries. The cervical arterial anastomoses are built by the segmental arteries of the vertebral arteries, in the back of the cervical vertebral bodies by the arteriae canalis vertebralis anteriores and in the front by the rami anteriores (corporum vertebrarum). The thyrocervical and the costocervical trunks are an additional blood supply especially to the ventral anastomoses. A loss of a segmental artery may have no effect because of the good anastomoses. Some decades of aa. nutriciae come in the vertebral body from all sides, but only 2 up to 4 rr. centrales anteriores and 2 rr. centrales posteriores join in the middle of the vertebral body. There are parallels to the arterial blood supply of the thoracal and the lumbar vertebral bodies. The longitudinal ligaments are supplied by both ladder patterns of arteries.     

Aspects of the life cycle and pathogenesis of Elaphostrongylus alces in moose (Alces alces).

Aspects of the migratory life cycle and pathogenesis of Elaphostrongylus alces were studied in 7 randomly selected moose calves and 7 yearlings killed during August to November. One calf and 1 yearling were uninfected. The 6 infected calves had recent infections, whereas the 6 yearlings showed older infections from the summer of the previous year. The 2 calves killed in September had a total of 26 adult E. alces in the epidural space of the caudal vertebral canal and none in the skeletal muscles, whereas the remaining calves killed 1 to 2 mo later had 25 nematodes in the caudal and cranial vertebral canal and 7 in the skeletal muscles. The yearlings had a total of 101 adult E. alces in the skeletal muscles and 2 in the vertebral canal. There were no findings indicating involvement of the central nervous system in the life cycle of E. alces. Our findings suggest that E. alces migrates directly from the gut to the epidural space of the caudal vertebral canal where development to the adult stage takes place. During development, the nematode produces inflammation of the epidural tissue and spinal nerves. Development in the caudal vertebral canal is followed by some anterior dispersion of nematodes along the canal, and migration into skeletal muscles. Here the nematodes seem to live in reproductive pairs and groups. The predilection site for E. alces in moose is the muscles of the thigh.     

Prediction of biomechanical parameters in the lumbar spine during static sagittal plane lifting.

A combined approach involving optimization and the finite element technique was used to predict biomechanical parameters in the lumbar spine during static lifting in the sagittal plane. Forces in muscle fascicles of the lumbar region were first predicted using an optimization-based force model including the entire lumbar spine. These muscle forces as well as the distributed upper body weight and the lifted load were then applied to a three-dimensional finite element model of the thoracolumbar spine and rib cage to predict deformation, the intradiskal pressure, strains, stresses, and load transfer paths in the spine. The predicted intradiskal pressures in the L3-4 disk at the most deviated from the in vivo measurements by 8.2 percent for the four lifting cases analyzed. The lumbosacral joint flexed, while the other lumbar joints extended for all of the four lifting cases studied (rotation of a joint is the relative rotation between its two vertebral bodies). High stresses were predicted in the posterolateral regions of the endplates and at the junctions of the pedicles and vertebral bodies. High interlaminar shear stresses were found in the posterolateral regions of the lumbar disks. While the facet joints of the upper two lumbar segments did not transmit any load, the facet joints of the lower two lumbar segments experienced significant loads. The ligaments of all lumbar motion segments except the lumbosacral junction provided only marginal moments. The limitations of the current model and possible improvements are discussed.     

腰丛-坐骨神经阻滞与腰硬联合麻醉用于老年患者下肢手术中的效果比较

目的:分析和比较两种不同麻醉方式(腰丛-坐骨神经阻滞麻醉与腰硬联合麻醉)对老年患者下肢骨折手术中的效果。方法:以我院收治的下肢骨折拟行手术治疗的老年患者158例作为研究对象,将其随机分为腰硬联合麻醉组(CSEA)和腰丛-坐骨神经阻滞组(LPSB),每组各79例。CSEA组采用腰硬联合麻醉,LPSB组采用腰丛-坐骨神经阻滞,比较两组患者感觉阻滞起效时间、运动阻滞起效时间、运动恢复时间、维持时间、疼痛感觉评分和并发症的发生状况。结果:CSEA组和LPSB分别有1例和3例患者因局部麻醉失效而需全身麻醉;LPSB组的感觉阻滞起效时间、运动阻滞起效时间、运动恢复时间均显著晚于CSEA组,但其维持时间显著长于CSEA组,患者疼痛感觉评分低于CSEA组(P0.05)。结论:与腰硬联合麻醉相比,腰丛-坐骨神经阻滞能为老年下肢骨折手术患者提供有效的单侧麻醉,且安全性高,可作为下肢骨科手术患者的首选麻醉方案。     

Control of the human and animal locomotor activity in the absence of supraspinal effects

In patients deprived of supraspinal effects, electrical epidural stimulation of the spinal cord's dorsal surface at the level of 2nd lumbar segment induces step-like movements accompanied by respective electromyographic activity of the leg's muscles. Triggering of the step-like movements occurs at certain parameters of the stimulation. The data obtained suggest that human spinal cord has networks of interneurons-generators of the step-like movements. A leading role of the spinal cord's propriospinal system in activation of spinal generators of stepping under epidural influences was shown in cats.