Evoked potentials from direct cerebellar stimulation for monitoring of the rodent spinal cord.

Although the assessment of spinal cord function by electrophysiological techniques has become important in both clinical and research environments, current monitoring methods do not completely evaluate all tracts in the spinal cord. Somatosensory and motor evoked potentials primarily reflect dorsal column and pyramidal tract integrity, respectively, but do not directly assess the status of the ventral funiculus. The present study was undertaken to evaluate the use of evoked potentials, elicited by direct cerebellar stimulation, in monitoring the ventral component of the rodent spinal cord. Twenty-nine rats underwent epidural anodal stimulation directly over the cerebellar cortex, with recording of evoked responses from the lower thoracic spinal cord, both sciatic nerves, and/or both gastrocnemius muscles. Stimulation parameters were varied to establish normative characteristics. The pathways conducting these "posterior fossa evoked potentials" were determined after creation of various lesions of the cervical spinal cord. The evoked potential recorded from the thoracic spinal cord consisted of five positive (P1 to P5) and five negative (N1 to N5) peaks. The average conduction velocity (+/- standard deviation) of the earliest wave (P1) was 53 +/- 4 m/sec, with a latency of 1.24 +/- 0.10 msec. The other components followed within 4 msec from stimulus onset. Unilateral cerebellar stimulation resulted in bilateral sciatic nerve and gastrocnemius muscle responses; there were no significant differences (p greater than 0.05) in the thresholds, amplitudes, or latencies of these responses elicited by right- versus left-sided stimulation. Recordings performed following creation of selective lesions of the cervical cord indicated that the thoracic response was carried primarily in the ventral funiculus while the sciatic and gastrocnemius responses were mediated through the dorsal half of the spinal cord. It is concluded that the posterior fossa evoked potential has research value as a method of monitoring pathways within the ventral spinal cord of the rat, and should be useful in the study of spinal cord injury.     

Chronic spinal compression model in minipigs: a systematic behavioral, qualitative, and quantitative neuropathological study

The goal of the present study was to develop a porcine spinal cord injury (SCI) model, and to describe the neurological outcome and characterize the corresponding quantitative and qualitative histological changes at 4-9 months after injury. Adult Gottingen-Minnesota minipigs were anesthetized and placed in a spine immobilization frame. The exposed T12 spinal segment was compressed in a dorso-ventral direction using a 5-mm-diameter circular bar with a progressively increasing peak force (1.5, 2.0, or 2.5?kg) at a velocity of 3?cm/sec. During recovery, motor and sensory function were periodically monitored. After survival, the animals were perfusion fixed and the extent of local SCI was analyzed by (1) post-mortem MRI analysis of dissected spinal cords, (2) qualitative and quantitative analysis of axonal survival at the epicenter of injury, and (3) defining the presence of local inflammatory changes, astrocytosis, and schwannosis. Following 2.5-kg spinal cord compression the animals demonstrated a near complete loss of motor and sensory function with no recovery over the next 4-9 months. Those that underwent spinal cord compression with 2 kg force developed an incomplete injury with progressive partial neurological recovery characterized by a restricted ability to stand and walk. Animals injured with a spinal compression force of 1.5?kg showed near normal ambulation 10 days after injury. In fully paralyzed animals (2.5?kg), MRI analysis demonstrated a loss of spinal white matter integrity and extensive septal cavitations. A significant correlation between the magnitude of loss of small and medium-sized myelinated axons in the ventral funiculus and neurological deficits was identified. These data, demonstrating stable neurological deficits in severely injured animals, similarities of spinal pathology to humans, and relatively good post-injury tolerance of this strain of minipigs to spinal trauma, suggest that this model can successfully be used to study therapeutic interventions targeting both acute and chronic stages of SCI.     

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.     

Axonal Sprouting Following Incomplete Spinal Cord Injury: An Experimental Model

Abstract

Recovery of function following incomplete spinal cord injury may in part result from growth of new connections by spared descending pathways. It has been difficult to demonstrate such anatomical reorganization with traditional anatomic techniques. This study utilizes an immunocytochemical method to demonstrate axonal growth cones within the lumbar spinal cord in rats recovering from an incomplete midthoracic spinal cord injury. Adult rats underwent subtotal section of the midthoracic cord sparing the left lateral funiculus and a portion of the left ventral funiculus. Light microscope immunocytochemistry was performed on sections of lumbar spinal cord with antibodies to identify sprouting axons. These antibodies were used to determine the distribution of growth cones on both sides of the lumbar spinal cord in experimental and control animals. Growth cones were first observed three days after the spinal cord lesion. Specific labeling, similar in appearance to previous reports of growth cone identification, was apparent within the intermediate gray and ventral horns on both sides of the cord. These data support the hypothesis of collateral sprouting distal to the lesion site following incomplete spinal cord injury. It further supports the idea that recovery of function following incomplete spinal cord injury is, in part, mediated by spared descending pathways. (J Spinal Cord Med 1997; 20:200-206)     

脊髓前动脉损伤后脊髓病理演变的实验研究

目的观察脊髓前动脉损伤后脊髓组织形态学演变过程,研究病理机制.方法以家犬为实验模型,损伤脊髓前动脉后进行肉眼、光镜和电镜动态观察,定量测定坏死神经元.结果脊髓前动脉损伤2h运动神经元变性,轴索病变,6h神经元坏死,24h脊髓水肿达到高峰,7d髓内出血最明显.在脊髓前动脉损伤节段,24h 30%～40%的运动神经元坏死,3d达80%,7d以后95%以上.病变均位于脊髓2/3.脊髓前动脉损伤节段变性坏死最严重,相邻节段其次,尾侧脊髓坏死量逐渐减少.结论脊髓前动脉损伤后脊髓缺血性病变是渐进和不可逆的,可引起广泛节段脊髓病变.     

Rescue of rat anterior horn neurons after spinal cord injury by retrograde transfection of adenovirus vector carrying brain-derived neurotrophic factor gene

We investigated the efficacy of retrograde gene delivery via the sternomastoid muscle of recombinant adenovirus vector (AdV) carrying brain-derived neurotrophic factor (BDNF) gene for the rescue of injured rat spinal cord. One hundred-thirty five adult Sprague-Dawley rats were used in the study with a standard weight-compression technique to produce spinal cord injury. AdV-BDNF gene or AdV-beta-galactosidase (AdV-LacZ) gene was injected into the sternomastoid muscle immediately after traumatic C4 segment spinal cord injury. AdV-BDNF was successfully appeared in the injured cervical spinal cord following injection into the sternomastoid muscle. BDNF expression in the anterior horn neurons of the cervical spinal cord reached peak levels at 1-2 weeks; and the expression persisted at significant levels for approximately 4 weeks after injury. AdV-BDNF transfection was associated with increased numbers of intact neurons as confirmed by Nissl, cholineacetyltransferase (ChAT), and acetylcholine esterase (AChE) staining especially from 2 weeks after injury, compared with the AdV-LacZ injected rats. Our results suggest that in vivo targeted retrograde AdV-BDNF-gene delivery may enhance neuronal survival following traumatic injury of the spinal cord.     

Anatomic location of spinal cord injury. Relationship to the cause of injury

In a population based sample, 550 of 619 people with fatal and nonfatal spinal cord injuries were classified according to the cause of injury and according to the anatomic location of the highest spinal cord injury. Motor vehicle occupants accounted for 42% of the people with spinal cord injuries. Sixty percent of those injured had a cervical cord injury, 25% a thoracic cord injury, and 15% a lumbosacral cord injury. The specific anatomic locations most commonly injured were at C1 (12% of all spinal cord injuries), C6 (9%), and L2 (5%). The anatomic site of injury was significantly (P less than 0.001) related to the cause of injury. Thirty-seven percent of the spinal cord injuries from firearms and 97% of those from diving were located in the cervical cord. In contrast, 68% of spinal cord injuries to motor vehicle occupants were cervical; 17% at C1. The distribution of injuries among drivers was similar to that among other occupants.     

Oxygenated fluorocarbon nutrient solution in the treatment of experimental spinal cord injury

We employed an extravascular perfusion system through the subarachnoid space of the traumatized spinal cord of the cat for the delivery of oxygen utilizing a fluorocarbon emulsion containing essential nutrients, termed the oxygenated fluorocarbon nutrient solution (OFNS). Animals perfused for 2 hours with saline after impact injury of the spinal cord had significantly less edema at 1 cm below this site of injury than injured, untreated animals. However, in injured animals perfused with OFNS there was significant protection from spinal cord edema at both 1 and 2 cm below the site of injury. OFNS perfusion reduced the magnitude of hemorrhagic necrosis in both the gray and the white matter and protected the anterior horn cells against lysis at the site of injury. Adenosine triphosphate (ATP) is decreased within 1 minute and remains suppressed for 1 hour in gray and white matter of unperfused, injured animals. The level of ATP in both gray and white matter was significantly higher in injured OFNS-perfused animals than in saline-treated animals at the site below the spinal cord injury. Our data show that OFNS perfusion of the injured spinal cord reduced necrosis and edema and tended to normalize the levels of high energy ATP and intact anterior horn cells. These results demonstrate the feasibility of treating ischemic hypoxia of the spinal cord after trauma through an extravascular perfusion route that utilizes a fluorocarbon emulsion as a vehicle for the delivery of oxygen and other cellular nutrients.     

减压对慢性压迫性脊髓损伤大鼠ChAT表达的影响

目的:探讨手术减压对治疗慢性脊髓损伤的作用机理。方法:采用大鼠后路渐进性脊髓压迫动物模型,然后进行手术减压,观察其联合行为评分(CBS),并常规行病理及胆碱乙酰转移酶(ChAT)的免疫组化检测。结果:脊髓损伤后ChAT免疫组化阳性细胞数减少,CBS升高;经手术减压治疗后,ChAT阳性细胞数增多,CBS也改善,减压组与压迫组比较差异具有显著性(P<0.05)。结论:手术减压治疗的作用机制可能是其促进了脊髓运动神经元合成ChAT,从而合成更多的运动神经递质———乙酰胆碱,加速了实验动物行为功能的恢复。     

Prevalence of cervical canal stenosis in farmers: Epidemiological study based on radiographic parameter of spinal cord injury patients

BackgroundFarming is one of the effective community activities for preventing the need for new long-term care insurance services. This study was conducted to compare spinal canal diameters between patients injured during orchard work (i.e., cultivating apples) and other situations that lead to cervical spinal cord injury without major fracture or dislocation and to investigate the frequency of cervical spinal canal stenosis among farmers in a Japanese community.MethodsSubjects were 23 patients with cervical spinal cord injury without major fracture and dislocation. Charts and radiographs of these patients were retrospectively reviewed to evaluate the characteristics of the spinal cord injury. The spinal canal diameter at the injury level in the mid-sagittal plane of magnetic resonance imaging (MRI) and mechanism of injury were compared between patients injured by orchard work and other situations. Moreover, 358 Japanese general residents were evaluated for the prevalence of cervical canal stenosis using MRI and comparisons were made between farmers group and non-farmers group.ResultsSpinal canal diameters at the injury level were 5.8 ± 1.4 mm in patients injured during orchard work and 5.6 ± 1.0 mm in those injured in other situations; there were no differences between the two groups. Head contusion as mechanism of injury was more frequent in the orchard work group than in other situations group. Among farmers, the rate of spinal canal stenosis increased with age, and it was 62.3% in men and 66.2% in women.ConclusionsThe frequency of cervical spinal canal stenosis was high with age regardless of farming work. In addition, head contusion might be a characteristic mechanism that causes spinal cord injury during orchard work. Therefore, screening of cervical degenerative conditions among farmers and education for prevention of cervical spinal cord injury during farming work are necessary.     

Histopathological and behavioral characterization of a novel cervical spinal cord displacement contusion injury in the rat

Cervical contusive trauma accounts for the majority, of human spinal cord injury (SCI), yet experimental use of cervical contusion injury models has been limited. Considering that (1) the different ways of injuring the spinal cord (compression, contusion, and transection) induce very different processes of tissue damage and (2) the architecture of the spinal cord is not uniform, it is important to use a model that is more clinically applicable to human SCI. Therefore, in the current study we have developed a rat model of contusive, cervical SCI using the Electromagnetic Spinal Cord Injury Device (ESCID) developed at Ohio State University (OSU) to induce injury by spinal cord displacement. We used the device to perform mild, moderate and severe injuries (0.80, 0.95, and 1.1 mm displacements, respectively) with a single, brief displacement of <20 msec upon the exposed dorsal surface of the C5 cervical spinal cord of female (180-200 g) Fischer rats. Characterization of the model involved the analysis of the temporal histopathological progression of the injury over 9 weeks using histochemical stains to analyze white and gray mater integrity and immunohistochemistry to examine cellular changes and physiological responses within the injured spinal cord. Accompanying the histological analysis was a comprehensive determination of the behavioral functionality of the animals using a battery of motor tests. Characterization of this novel model is presented to enable and encourage its future use in the design and experimental testing of therapeutic strategies that may be used for human SCI.     

Increased survival and reinnervation of cervical motoneurons by riluzole after avulsion of the C7 ventral root

Although adult motoneurons do not die if their axons are injured at some distance from the cell body, they are unable to survive injury caused by ventral root avulsion. Some of the injured motoneurons can be rescued if the ventral root is re-inserted into the spinal cord. Brachial plexus injuries that involve the complete or partial avulsion of one or more cervical ventral roots can be treated successfully only if satisfactory numbers of motoneurons remain alive following such an injury at the time of reconstructive surgery. Here we investigated the various strategies that could be used to rescue injured rat cervical motoneurons. The seventh cervical ventral root (C7) was avulsed and various therapeutic approaches were applied to induce motoneuronal survival and regeneration. Avulsion of the root without reimplantation resulted in very low numbers of surviving motoneurons (65?±?8 SEM), while treatment of the injured motoneurons with riluzole resulted in high numbers of surviving motoneurons (637?±?26 SEM). When the C7 ventral root was reimplanted or a peripheral nerve implant was used to guide the regenerating axons to a muscle, considerable numbers of motoneurons regenerated their axons (211?±?15 SEM and 274?±?28 SEM, respectively). Much greater numbers of axons regenerated when reimplantation was followed by riluzole treatment (573?±?9 SEM). These results show that injured adult motoneurons can be rescued by riluzole treatment, even if they cannot regenerate their axons. Reinnervation of the peripheral targets can also be further improved with riluzole treatment.     

Changes in neuronal receptive field characteristics in caudal brain stem following chronic spinal cord injury.

Chronic spinal cord injury pain is poorly understood and, thus, not effectively relieved by traditional treatments. In the present study, a variety of partial, severe and sham chronic spinal lesions were made in 31 male rats at spinal level T8. During routine care/handling and brief behavioral testing of the animals throughout the 30-day recovery period, the majority of those with severe contusion injuries (verified histologically) showed signs of mechanical hypersensitivity on the dorsolateral trunk just rostral to the level of injury (i.e., upper thoracic territory). Terminal electrophysiological experiments were performed on all rats (urethane anesthesia). Single unit recordings were made at two supraspinal locations within the caudal brainstem, the nucleus reticularis gigantocellularis and nucleus reticularis gigantocellularis pars alpha. Neurons in these areas normally receive bilateral nociceptive somatovisceral inputs from many parts of the body. Seventy-three percent of the animals with severe contusion injuries developed novel low-threshold neuronal responses to stimulation of the dorsolateral trunk (upper thoracic territory). This amount was significantly greater than for animals with more moderate spinal lesions (dorsal or lateral hemisection; 29% and 25%, respectively) or sham controls (0%). These data suggest (1) that the spinal contusion is a reliable model for studies of the neural mechanisms that underly central spinal cord injury-related pain and (2) that the caudal brainstem is one supraspinal location where neurons undergo significant changes in responsiveness following severe chronic spinal cord injury. The observed plasticity is likely part of the central reorganization producing the multitude of sensory disturbances that surface following spinal cord injury.     

Relationship between posttraumatic ischemia and hemorrhage in the injured rat spinal cord as shown by colloidal carbon angiography

Adult female Wistar rats underwent extradural clip compression injury of the spinal cord at T-1. A force of 40 g was applied for 1 minute; this moderately severe injury renders animals paraparetic. We performed colloidal carbon angiography with Aquablak on four animals at 15 minutes, 2 hours, and 24 hours after injury. The entire spinal cord was then removed, frozen, and sectioned serially at 250 micron. The sections were examined microscopically for patterns of ischemia and hemorrhage at the site of compression injury and at adjacent and remote sites in the spinal cord. There was a marked lack of filling of the arterioles, capillaries, and venules at the injury site. In addition, there was a specific anatomical distribution of the ischemic areas in that ischemia of the white matter occurred in areas supplied by arteries that traversed adjacent hemorrhagic gray matter. For example, ischemia of the ventral funiculus was consistently seen adjacent to hemorrhage in the ventral gray matter. Similarly, ischemia of the dorsal white columns was related to hemorrhagic lesions surrounding the feeding vessels in the dorsal gray matter. This study also demonstrates the usefulness of a new colloidal carbon suspension (Aquablak) for documenting the pathophysiology of posttraumatic ischemia of the spinal cord. The results suggest that ischemic lesions in the white matter are anatomically related to hemorrhagic lesions in the gray matter. The pathophysiology of this relationship is unknown, but may include thrombosis, vasospasm, or direct injury of the feeding vessels.     

Cervical spinal cord injury in children.

We examined 19 children under 10 years of age with cervical spinal cord injury using clinical records and radiographs. The children were divided into two groups: Eight had immediate and complete spinal cord injury, and 11 had incomplete or partial spinal cord injury. Those with complete spinal cord injury were injured in motor vehicle accidents with a proximal spinal cord injury. Eighty-eight percent had cervical spine fractures/instability with a distraction pattern of injury. Half had associated trauma. The mortality rate was 25%, and those who survived showed no neurologic improvement. Most of the children with partial spinal cord injury were injured at birth. Many had no radiographic evidence of cervical fracture. One-quarter had associated trauma. The neurologic improvement averaged 1.9 Frankel grades. Half of both groups required posterior cervical fusion, and there was a significant complication rate. Eight-eight percent developed scoliosis, and 71% developed hip subluxation.     

急性颈髓损伤后应激性溃疡的临床特点及治疗

目的 :总结急性颈髓损伤后应激性溃疡的临床特点及治疗体会。方法 :将 2 89例急性颈髓损伤患者按是否并发应激性溃疡 ,分为发病组和未发病组 ,并对两组的临床资料进行比较 ,其中包括 :性别、年龄、损伤平面、损伤程度、合并伤、并发症及早期应用激素。同时回顾性分析应激性溃疡的治疗方法。结果 :在年龄≥ 5 5岁、损伤平面在C4以上、完全性脊髓损伤、合并其它脏器损伤、并发肺内感染及早期应用大剂量甲基强的松龙方面 ,发病组与未发病组之间的差异具有显著性意义。经综合治疗 2 4h内出血停止 8例 ,2 4～ 48h出血停止 6例 ,48～ 72h出血停止 1例 ,1例因并发多脏器功能衰竭而死亡。结论 :急性颈髓损伤后应激性溃疡的发生与年龄、颈髓损伤的平面、损伤程度、合并伤、并发肺内感染及脊髓损伤后早期用药有关。诊断后应采取综合治疗     

Loss of autoregulation and posttraumatic ischemia following experimental spinal cord trauma.

Blood flow in the dorsolateral funiculus of the cat thoracic spinal cord was studied after severe experimental cord injury, using a modification of the hydrogen clearance technique. Autoregulation was intact during the initial 60 to 90 minutes after cord injury, but was then lost coincident with the onset of ischemia. The data suggest that the ischemic response to spinal cord injury is mediated both by the loss of autoregulation and by relative vasoconstriction of the resistance vessels. Therapeutic intervention aimed at maintaining perfusion during the early posttraumatic period may prove of value in reversing or limiting some elements of dysfunction due to the secondary injury of ischemia.     

Follow-up CT myelography of severe cervical spinal cord injury

There are many reports describing gross anatomical and microscopical findings of severely injured cervical cords in autopsy of the acute and chronic state, but no morphological findings of a severe cervical spinal cord injury in a chronic state by follow-up CT myelography have been found in the literature so far. The sagittal and transverse diameters of the cervical spinal cord and subarachnoid space of 9 out of 14 severe cervical spinal cord injury patients were measured with CT myelography within 7.5 years after the trauma and their size compared with a control group which was made up of 29 patients with slight radiculopathy due to cervical spondylosis and whiplash injuries. Injured cord levels were C4 4 cases, C5 4 cases and C6 1 case. Remarkable spinal cord atrophy was recognized in the sagittal diameter from C1 to C7 and in the transverse diameter below C4 and narrowing of the cervical subarachnoid space in the sagittal diameter from C2 to C5. The significance level was set at 1-5%. From these findings, we have concluded that atrophy appeared not only in the injured segment but also the whole cervical cord after the trauma. There was less cord atrophy in a good functional prognosis than in a poor prognosis.     

In vivo magnetic resonance imaging of fetal cat neural tissue transplants in the adult cat spinal cord.

Magnetic resonance (MR) imaging was evaluated for its possible diagnostic application in determining the survival of fetal central nervous system tissue grafts in the injured spinal cord. Hemisection cavities were made at the T11-L1 level of eight adult female cats. Immediately thereafter, several pieces of tissue, either obtained from the fetal cat brain stem on embryonic Day 37 (E-37), from the fetal neocortex on E-37, or from the fetal spinal cord on E-23, were implanted into the cavities made in seven cats. The eighth cat served as a control for the effect of the lesion only. In another group of four animals, a static-load compression injury was made at the L-2 level. Seven weeks later, the lesion was resected in three cases and fragments of either fetal brain-stem or spinal cord tissue were introduced. A small cyst was observed in a fourth cat in the compression injury group and a suspension of dissociated E-23 brain-stem cells was injected into this region of cavitation without disturbing the surrounding leptomeninges. Five months to 2 years posttransplantation, MR imaging was performed with a 2.0-tesla VIS imaging spectrometer by acquiring multislice spin-echo images (TR 1000 msec, TE 30 msec) in both the transverse and sagittal planes. Collectively, these intermediate-weighted images revealed homogeneous, slightly hyperintense signals at the graft site relative to the neighboring host tissue in seven of the 11 graft recipients. Two of the remaining four cats exhibited signals from the graft site that were approximately isointense with the adjacent host spinal cord, and the final two cats and the lesion-only control presented with very hypointense transplant/resection regions. The hyperintense and isointense images were tentatively interpreted as representing viable graft tissue, whereas the hypointense transplant/resection sites were considered to be indicative of a lack of transplant survival or the absence of tissue in the lesion-only control animal. Postmortem gross inspection of fixed specimens and light microscopy verified the MR findings in the control animal in 10 of the 11 graft recipients by showing either transplants and/or cysts corresponding to the MR images obtained. In one cat in the hemisection group, histological analysis revealed a very small piece of graft tissue that was not detected on the MR images. Therefore, it is suggested that within certain spatial- and contrast-resolution limits, MR imaging can reliably detect the presence of transplanted neural tissue in both the hemisected and compression-injured spinal cord of living animals.(ABSTRACT TRUNCATED AT 400 WORDS)     

Uptake and elimination of methylprednisolone from contused cat spinal cord following intravenous injection of the sodium succinate ester

The uptake and elimination of methylprednisolone by the injured cat lumbar spinal cord were examined following a single 30-mg/kg intravenous bolus injection of the sodium succinate ester. The findings were considerably different from those previously reported for normal lumbar cord. When the glucocorticoid was administered 30 minutes after a 400 gm-cm contusion injury, peak tissue concentrations in both injured and uninjured segments of traumatized spinal cord were not achieved until 30 minutes following drug administration. The elimination of methylprednisolone from injured spinal cord tissue was biphasic in nature, with a rapid elimination phase occurring between 1 and 2 hours after drug administration. This rapid elimination phase was followed by a slower phase which paralleled the constant elimination rate from uninjured tissue of traumatized cord (approximate half-time = 6 hours). Significantly more methylprednisolone accumulated in the injured segment of traumatized spinal cord than in an uninjured segment adjacent to the injury site. This was only true, however, if the drug was administered at times up to 1 hour after injury. If injected after 1 hour, uptake by the injured segment decreased significantly with time after trauma and was no different from that observed for the uninjured segment in the same animal, which showed no significant variation with time after trauma. The probable basis for these differences and the possible clinical implications of these pharmacokinetic characteristics are discussed.