Pathological changes of isolated spinal cord axons in response to mechanical stretch

White matter strips extracted from adult guinea-pig spinal cords were maintained in vitro and studied physiologically using a double sucrose gap technique and anatomically using a horseradish peroxidase assay. The amplitude of compound action potentials was monitored continuously before, during, and after elongation. Three types of conduction blocks resulting from stretch injury were identified: an immediate, spontaneously reversible component, which may result from a transient increase in membrane permeability and consequent disturbance of ionic distribution; a second component that was irreversible within 30–60 min of recording, perhaps resulting from profound axolemmal disruption; and a third component, which may be due to perturbation of the myelin sheath, that was reversible with application of 100 μM of the potassium channel blocker, 4-aminopyridine. The intensity of the conduction deficits correlated with the extent of initial stretch over a full range of severity. Stimulus–response data indicate that mechanical damage to axons in stretch was evenly distributed across the caliber spectrum. Morphological examinations revealed that a small portion of axons exhibited membrane damage at 2 min following stretch and appeared to be largely sealed at 30 min after injury. Further, in the entire length of the cord strip subjected to stretch, axons closer to the surface were found to be more likely to suffer membrane damage, which distinguished stretch injury from compression injury.

In summary, we have developed an in vitro model of axonal stretch that provides the ability to monitor changes in the properties of central myelinated axons following stretch injury in the absence of pathological variables related to vascular damage. This initial investigation found no evidence of secondary deterioration of axons in the first 30 min after stretch in vitro, although there was evidence of both transient and lasting physiological and anatomical damage to axons and their myelin sheaths.     

Morphofunctional changes in the rat spinal cord after focal photothrombosis

The aim of the present work was to study pathomorphological and functional changes after induced focal photothrombosis of blood vessels in the thoracic part of the spinal cord in rats. Neuron abnormalities characteristic of ischemia were seen at the focus of experimental photothrombosis and in the transitional zone, along with symptoms of impaired motor and pelvic organ function. The focal photothrombosis method can be used to model spinal cord ischemia for the development of pharmacological correction methods and the recovery of impaired sensorimotor functions. Translated from Morfologiya, Vol. 133, No. 1, pp. 35–38, January–February, 2008.     

基于体素的形态学分析在脊髓损伤中的研究进展

创伤性脊髓损伤（SCI）通常会导致大脑皮质发生继发性损害,造成神经元凋亡或萎缩。基于体素的形态学（VBM） 技术凭借其无创性、精确性的优点,已在SCI患者大脑微观结构变化的研究中得到了广泛应用。本文主要从损伤后皮质 萎缩情况及其与患者临床表现间相关性的横向研究结果,损伤早期进行性神经退变的时空模式及其对患者临床结果预测 能力的纵向研究结果,损伤持续时间（亚急性、慢性等）、损伤严重程度（完全性、不完全性等）、临床康复情况（感觉运动功 能、神经性疼痛等）等因素对研究结果的不同影响这3个方面对VBM在SCI中的研究进展进行综述,并指出未来研究应进 一步提高VBM技术的可靠性,同时完善研究方案的设计,以促进VBM在脑功能探索和SCI康复治疗中的作用。     

Nontumor lesions of spinal cord and spine

Nontumor lesions of the spinal cord and spine include developmental disorders, cystic tumor-like lesions, vascular disorders, infective diseases, demyelinating diseases, degenerative diseases, metabolic and toxic disorders, and spinal cord injury. In addition, diseases of the spine and extradural spaces secondarily cause spinal cord injury. Aside from tumors, these include developmental abnormalities, inflammatory diseases, nontumor space-occupying lesions, and tumor-like lesions such as lipomas, vascular malformations, and cysts. Awareness is required of hemostatic agents used during surgery and subsequently presenting as space-occupying lesions, which have to be differentiated from recurrent lesions. On the therapeutic front, stem cell transplantation into spinal cord for treatment of neurodegenerative disorders, spinal cord injury, and multiple sclerosis is a challenging prospect.     

Location of the spinal nucleus of the accessory nerve in the human spinal cord

The segmental extent and topography of the spinal nucleus of the accessory nerve (SNAN) was investigated in the adult human spinal cord. Transverse sections of segments between the lower medulla and C6 were stained with cresyl violet and the motor cell columns identified according to the numerical locations defined by Elliott (1942). The segmental extent and topography of the cervical part of column 2 resembled that previously described for the SNAN of primates.     

A variation of the tissue print technique for studying isolated spinal cord cells in situ

We present a novel variation of the tissue print technique which yields isolated spinal cells that retain their original topographical organization in situ. A light papain digestion combined with a low-melting-point agarose as the adhesive substrate is used to ‘print' a monolayer of cells from spinal cord slices. Printed cells are viable for studies using electrophysiological approaches. This technique provides a means to bridge the gap between properties of isolated cells and their topographical identity in spinal cord.     

Electron microscopic study of the median structure of the posterior column of the spinal cord of the adult rat with a special reference to the posterior median septum

In neuroanatomy textbooks on humans, the posterior median septum is commonly depicted along the midline of the posterior column of the spinal cord. For intramedullary spinal cord tumors, the standard surgical treatment is posterior midline myelotomy. However, its anatomical basis is still unclear. Therefore, in this study we focused on the ultrastructural characterization of the median structure of the posterior column in an adult rat. In the median part of the fasciculi gracilis, a fine lineal tissue continued from the posterior median sulcus to the 3/4th depth of the fasciculi. At higher magnification, this fine lineal tissue consisted of bundles of astrocytes, which are often disrupted and eventually disappeared. At the junction of the ventral part of the fasciculi cuneatus and the gray commissure, short lineal figures of glial tissues extended dorsally. These lineal figures of glial tissues were morphologically similar to other lineal figures of glial tissues found in the posterior column; bundles of astrocytes extending along the axons that entered the gray commissure and the perivascular lineal figures of glial tissues. In conclusion, this study revealed that the posterior median septum is composed of very fine lineal figures of glial tissues that are often disrupted and eventually disappear. We consider these basic structures to be similar in humans. Therefore, during posterior midline myelotomy, accurately separating along the posterior median septum in the posterior column is extremely difficult.     

MR-based measurement of spinal cord motion during flexion of the spine: implications for intradural spinal cord stimulator systems

This study develops a means of delivering electrical stimuli directly to the pial surface of the spinal cord for treatment of intractable pain. This intradural implant must remain in direct contact with the cord as it moves within the spinal canal. Therefore, magnetic resonance imaging was used to measure the movement of the spinal cord between neutral and flexed-back positions in a series of volunteers (n?=?16). Following flexion of the back, the mean change in the pedicle-to-spinal cord dorsal root entry zone distance at the T10-11 level was (8.5?±?6.0) mm, i.e. a 71% variation in the range of rostral-caudal movement of the spinal cord across all patients. There will be a large spectrum of spinal cord strains associated with this observed range of rostral-caudal motions, thus calling for suitable axial compliance within the electrode bearing portion of the intradural implant.     

Location of the phrenic nucleus in the human spinal cord

Eight normal human spinal cords were studied. Spinal segments were identified and embedded in paraffin wax. Serial cross sections were cut at 25 μm and stained by cresyl violet. Motor columns were reconstructed adapting Elliott's (1942) methods. Motor columns were classified into the medial and lateral divisions and were numbered sequentially from medial to lateral at the level of Cl. In the cervical cord, 8 motor columns were traced. Column 1, corresponding to the medial column, presented 3 subdivisions designated as 1a, 1b and 1c with ventral, dorsal and lateral positions respectively. Columns 1a and 1b extended throughout the cervical region while 1c was confined to 3rd, 4th and 5th cervical segments. At the level of C3, 1c was a discrete column situated lateral to 1a and 1b but at C4 and C5 it became displaced medially close to the medial margin of the ventral horn. In cross section, it presented smaller medial and large lateral part. With the help of clinical and developmental evidence an attempt was made to correlate column 1c with the phrenic nucleus.     

Shh/Gli1信号参与小鼠脊髓损伤后血-脊髓屏障渗透性改变及运动功能恢复

目的:探讨sonic hedgehog/Gli1(Shh/Gli1)信号在小鼠脊髓损伤后病理变化及运动功能恢复中的作用。方法:成年雄性C57野生型、Gli1lz和Gli1lz/lz小鼠行T8节段脊髓夹伤及假手术。Gli1lz小鼠脊髓损伤及假手术后3 d行X-gal染色;7 d行Shh/PDGFr-α、Shh/GFAP、LacZ/GFAP染色,观察Shh/Gli1信号在小鼠脊髓损伤后的激活。C57野生型和Gli1lz/lz小鼠脊髓夹伤后7 d行GFAP染色和实时定量RT-PCR,观察星形胶质细胞反应;术后14 d尾静脉注射伊文氏兰观察血-脊髓屏障改变;术后1、3、5 d和7 d行BMS评分评价小鼠后肢运动功能。结果:脊髓损伤7 d后,损伤区Shh表达升高;Shh/Gli1信号报告基因LacZ表达升高,主要表达于反应性星形胶质细胞;免疫组织化学及实时定量RT-PCR结果显示Gli1基因敲除不影响脊髓损伤后GFAP表达;伊文氏兰染色及其定量分析显示Gli1lz/lz小鼠脊髓损伤后脊髓组织伊文氏兰外渗增加。BMS评分显示Gli1lz/lz小鼠运动功能恢复显著差于野生型小鼠。结论:Shh/Gli1信号在小鼠脊髓损伤后激活,可能参与脊髓损伤后血-脊髓屏障渗透性的改变,并影响脊髓损伤后的运动功能恢复。     

Electromyographic assessment of damage to the injured spinal cord

The possibility of assessing the degree of damage to the spinal cord by electromyography in the early stage of treatment was demonstrated. The following indices obtained during attempts at movement are evidence of the absence of anatomical loss of continuity of the spinal cord: 1) in the case of injury at level D₅–D₁₀, absence of delay in activation of the lower segments of the long muscles of the trunk compared with their upper segments; 2) in the case of trauma at the level D₁₀-L₁, the presence of activity in the thigh and leg muscles, even if recordable only as single potentials of low amplitude; 3) whatever the level of trauma, the appearance of activity in symmetrical muscles of one lower limb during the attempt to move the opposite limb. In most cases, even if only one index is positive, the patient's motor functions will be restored by restitution.Material for this work was obtained by periodic examination of patients under treatment by Dr. A. N. Trankvillitati, Honored Physician of the RSFSR. Neurological examinations in the course of the investigation were made by Candidate of Medical Sciences L. S. Goncharova.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. A. Vishnevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 80, No. 10, pp. 25–29, October, 1975.     

结扎数支肋间后动脉对胸腰段脊髓血供影响

目的：探讨在脊柱侧凸前人路手术中结扎第7～11肋间后动脉对脊髓血供的影响。方法：将11例14～50岁、无严重心血管疾病和中枢神经系统无损伤的新鲜尸体随机分在A组(不手术)、B组和C组(分别结扎左侧和双侧第7～11肋间后动脉起始部)，全身墨汁福尔马林灌注，取T5～L1段脊髓作250μm连续冰冻切片，镜下观察和拍照，并进行测量和统计分析。结果：C组标本的节段间血管数及血管密度有显著性差异；A组与B组及A组与C组某些节段的血管数或／和血管密度存在差异。结论：胸腰段脊髓的血供不存在节段间差异，双侧结扎第7～11肋间后动脉起始段对脊髓血供影响较大，单侧结扎第7～11肋间后动脉起始段对胸腰段脊髓血供有影响。     

Regeneration of the rat spinal cord after thoracic segmentectomy: Restoration of the anatomical integrity of the spinal cord

Segmentectomy of the spinal cord (SC) was performed in 28 rats at the level of the tenth thoracic vertebra. Scar formation at the operation site was studied, along with the completeness of the anatomical integrity of the SC, in control animals (group 1) and after filling of the defect with the neural matrix Spherogel (group 2) and with Spherogel containing embryonic nerve cells (group 3). The defect in the SC in animals of the control group was filled with fibrin masses by 1–2 weeks, while connective tissues scars were already formed by this time in rats of experimental groups 2 and 3. By 10–11 weeks, these animals showed partial recovery of movement in the three lower limb joints. The scar tissue and adjacent zones of the SC showed large quantities of regenerating fine myelinated nerve fibers. These were clearly evident in the zones of the cranial and caudal margins, to the extent of the appearance of typical SC tissue. In preparations obtained from control animals, fine myelinated fibers were noted in the immediate vicinity of SC substance, while nerve fibers were few in number in scar tissue and the cellular bands of the transitional zone. __________ Translated from Morfologiya, Vol. 127, No. 2, pp. 39–43, March–April, 2005.     

Effect of narcotic analgesics on transmission of excitation in the spinal cord

In experiments on unanesthetized, curarized spinal cats, morphine, trimeperidine, and fentanyl caused no change in the amplitude of evoked potentials in the ventrolateral columns in the lumbar region of the spinal cord in response to single or repetitive stimulation of a cutaneous or pelvic nerve. In some experiments these preparations inhibited neurons of the posterior horns of the spinal cord that are activated by nociceptive stimulation of peripheral receptors or by intraarterial injection of bradykinin. It is suggested that a spinal component exists in the action of the narcotic analgesics.Laboratory of Pharmacology of the Nervous System, Institute of Pharmacology, Academy of Medical Sciences of the USSR. Department of Pharmacology, I. M. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 182–185, February, 1978.     

脊髓血供的计量学观察

目的 :探讨脊髓内部血管构筑和分布 ,为脊髓缺血性的有关病变、治疗和预后提供形态学基础。方法 :应用碱性磷酸酶血管染色法 ,对脊髓内部血管 ,用体视学方法作计量和观察。结果 :在脊髓内部灰、白质的毛细血管体密度 ,表面积密度、长度密度存在着差异。结论 :灰质内毛细血管的体密度 ,表面积密度、长度密度均明显高于白质 ,灰质前角的毛细血管量明显多于后角 ,而白质毛细血管的体密度是 :前索 >侧索 >后索     

Glia to neuron ratio in the posterior aspect of the human spinal cord at thoracic segments relevant to spinal cord stimulation

Spinal cord stimulation (SCS) applied between T8 and T11 segments has been shown to be effective for the treatment of chronic pain of the lower back and limbs. However, the mechanism of the analgesic effect at these medullary levels remains unclear. Numerous studies relate glial cells with development and maintenance of chronic neuropathic pain. Glial cells are electrically excitable, which makes them a potential therapeutic target using SCS. The aim of this study is to report glia to neuron ratio in thoracic segments relevant to SCS, as well as to characterize the glia cell population at these levels. Dissections from gray and white matter of posterior spinal cord segments (T8, T9, intersection T9/T10, T10 and T11) were obtained from 11 human cadavers for histological analyses. Neuronal bodies and glial cells (microglia, astrocytes and oligodendrocytes) were immunostained, microphotographed and counted using image analysis software. Statistical analyses were carried out to establish significant differences of neuronal and glial populations among the selected segments, between the glial cells in a segment, and glial cells in white and gray matter. Results show that glia to neuron ratio in the posterior gray matter of the human spinal cord within the T8–T11 vertebral region is in the range 11 : 1 to 13 : 1, although not significantly different among vertebral segments. Glia cells are more abundant in gray matter than in white matter, whereas astrocytes and oligodendrocytes are more abundant than microglia (40 : 40 : 20). Interestingly, the population of oligodendrocytes in the T9/T10 intersection is significantly larger than in any other segment. In conclusion, glial cells are the predominant bodies in the posterior gray and white matter of the T8–T11 segments of the human spinal cord. Given the crucial role of glial cells in the development and maintenance of neuropathic pain, and their electrophysiological characteristics, anatomical determination of the ratio of different cell populations in spinal segments commonly exposed to SCS is fundamental to understand fully the biological effects observed with this therapy.