异氟醚麻醉下人身体感觉诱发电位的改变

目的：探讨脊髓是异氟醚的重要作用部位,方法：对18例妇科手术患者行异氟醚麻醉,并以硬膜外阻滞作对照,刺激踝部胫神经,监测并记录头颈部体感诱发电位,记录分3个阶段：基础值,异氟醚麻醉,硬膜外腔阻滞,结果：异氟醚麻醉,硬膜外腔阻滞均可使下肢体感诱发电位的潜伏期明显延迟,结论：异氟醚麻醉对脊髓具有明显的抑制作用,脊髓可能是异氟醚麻醉作用的重要中枢部位。     

Effect of mannitol administration and myelotomy on acute experimental spinal cord injury: investigation by spinal cord evoked potential

The authors reported the changes in spinal cord evoked potential following impact injury by the weight-dropping technique in untreated and treated animals. The effect of mannitol and myelotomy therapy on spinal cord evoked potential in experimental spinal cord injury was discussed. (Materials and Methods) 32 adult dogs, ranging in weight from 9 to 13 kg, were used. 28 dogs received 300 gm-cm contusion of the T10 spinal cord. Eight dogs were not treated and twenty dogs were treated with mannitol. Ten dogs were treated with intravenous continuous infusion of mannitol (1g/kg/hr) 30 minutes after the injury, and ten dogs with intravenous bolus injection of mannitol (2 g/kg) at 30 minutes and 3 hours after the injury. At one hour after the injury, five dogs with 400 gm-cm contusion were treated with posterior midline myelotomy. The spinal cord evoked potential following direct stimulation of the spinal cord was recorded from the epidural space for 5 hours. The recording electrode was located cephalad to the site of the impact injury. (Results and Discussion) In each group, the amplitude of I potential decreased remarkably immediately after the injury. Subsequently, gradual recovery was obtained. In the untreated 300 gm-cm contusion group, no apparent improvement was seen from one hour after injury. On the other hand, in the mannitol-treated group, the recovery of the amplitude was superior to that found in the untreated group at a significant level of P less than 0.05. However, in the group with intravenous bolus injection of mannitol, the recovery was transient.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental study of spinal cord evoked potentials in cats

Assessment of function of the spinal cord utilizing spinal cord evoked potentials (SEP) has become a useful diagnostic tool. In the present study, various aspects of characteristics of SEP were analyzed. The basic waveform of conductive SEP consisted of two major components, namely, N1 and N2, whose conduction velocities along the dorsal surface of the cord were 74 m/s and 55 m/s, respectively. Halothane inhalation caused reduction of N2 amplitude, whereas asphyxia caused latency delay of N2. Significant amplitude reduction of N1, N2 (p less than 0.005) and considerable latency delay of N1 were noted in ventral epidural recording. Although there was no relationship between severity of injury and the appearance of positive potentials, N2 tended to be positive-going in heavy injury. Findings of positive potentials showed that N1 originated in the area of ventral gray matter through the ventro-lateral column and N2 through the dorsal column.     

脊髓急性牵拉损伤动物模型机理研究

目的对犬脊髓(神经根)急性牵拉损伤的病理机制进行初步探讨。方法12只健康成年杂种犬，随机分为对照组和不同程度牵拉损伤组。前后路联合手术离断脊柱后施加纵向牵拉损伤，对牵拉应变率、体感诱发电位(SEP)、神经源性脊髓运动诱发电位(NMEP)、硬膜下压力(SP)、硬膜血流量(EBF)等进行持续观察。伤后取脊髓及神经根标本进行HE、髓鞘神经中丝(NF)及胶原纤维酸性蛋白(GFAP)抗体免疫组织化学染色及电镜超微结构观察。结果牵拉损伤涉及牵拉节段和其上下脊髓及神经根的损伤。牵拉后出现硬膜下压力的显著增高和硬膜血流的显著降低。SEP异常的出现较NMEP更早。结论牵拉后脊髓内压力的增加导致脊髓血流减少。以及直接的机械性牵拉损伤可能是脊髓牵拉损伤的重要机制。     

脊椎截骨后脊柱短缩安全范围的实验研究

目的 探讨单脊椎切除对脊髓形态和功能的影响,并确定脊柱短缩的安全范围.方法 采用120只4～5月龄健康雄性新西兰大耳白兔,随机分为单椎板切除(A)组、双椎板切除(B)组及三椎板切除(C)组,每组40只,行L3全脊椎切除术.再根据压缩L3椎体总体高度的25%、50%、75%及100%将每组分成4个亚组.每亚组10只.测量不同脊柱短缩程度下硬膜囊长度、迂曲最大处硬膜囊直径、硬膜囊-神经根交角、硬膜囊矢状位迂曲角、术中体感诱发电位变化情况及Tarlov评分.术后72 h处死动物,HE染色观察脊髓皱缩最严重部位病理改变情况.结果 压缩高度≤总体高度50%时,各组硬膜囊均出现一定程度的形变,但术中脊髓功能监护及术后Tarlov评分差异无统计学意义(P>0.05);病理切片仅A组可见脊髓出现少量出血灶.压缩高度为总体高度75%时,A组硬膜囊形变及Tarlov评分与术前相比差异均有统计学意义(P<0.05),且与B组及C组比较差异有统计学意义(P<0.05);A组病理切片可见髓内出血灶增多、白质水肿,而B组及C组仅出现少量髓内出血灶.完全压缩时,B组及C组硬膜囊形变及术后Tarlov评分差异有统计学意义(P<0.05);病理切片见A组出现大片出血、神经元皱缩,而B组及C组可见髓内较多出血灶.结论 脊柱短缩的高度及椎板切除范围对脊髓形态及功能有较大影响.单椎板切除组压缩安全范围仅为总体高度的50%,而双椎板及三椎板切除组可安全压缩至75%.同样压缩高度下,增加椎板切除范围町有效改善脊髓迂曲、避免术中脊髓皱缩造成的脊髓损伤.     

Intra-operative spinal cord monitoring during surgery for scoliosis using somatosensory evoked potentials

The method of intra-operative monitoring of spinal cord function by spinal somatosensory evoked potentials (SEP), as used at the Royal Alexandra Hospital for Children during surgery for scoliosis is described. Using a non-polarisable platinum spinal epidural electrode, SEP elicited by tibial and peroneal nerve stimulation in the popliteal fossa are recorded proximal to the level of spinal correction. The large amplitude and discrete waveform of the SEP enable rapid signal acquisition and easy interpretation. The spinal SEP is stable under both therapeutic hypotension and general anaesthesia. Electrophysiological monitoring has now superceded the 'wake-up' test as an index of spinal cord function during corrective surgery for scoliosis.     

The pathogenesis of spinal epidural abscess: microangiographic studies in an experimental model

An experimental model of spinal epidural abscess was developed in rabbits by injecting Staphylococcus aureus into the posterior thoracolumbar epidural space. This model has been shown to reproduce the neurological, bacteriological, and radiological aspects of the human disease. In this study, the effect of the infectious epidural mass on the vasculature of the spinal cord in paraplegic rabbits was studied using microangiographic techniques. The normal vascular anatomy of the rabbit spinal cord was defined in control experiments. Vascular proliferation was demonstrated in the epidural space surrounding the abscesses. Anterior and paired posterior spinal arteries remained patent in paraplegic rabbits with mild or moderate spinal cord compression and in some cases of severe compression. In animals with severe compression, the anterior epidural venous plexus remained patent, but the dorsal spinal vein was occluded. Occlusion of perforating arteries occurred only with extreme spinal cord compression. These data indicate that the initial neurological deficit associated with experimental spinal epidural abscess is not due to vascular thrombosis.     

The effects of topical L-arginine and Ng-nitro-L-arginine methyl ester after experimental acute spinal cord injury. A light and electron microscopic study

The primary objective of this study was to investigate the effects of topical L-arginine and Ng-nitro-L-arginine methyl ester vs the role of ischemia in contributing to secondary injury after experimental acute spinal cord trauma. Twenty-six rabbits were submitted to spinal cord compression at the T7/8 level. The animals were divided into three groups: no applied drug (n=6), L-arginine (n=10), and Ng-nitro-L-arginine methyl ester (n=10). L-arginine was topically administered at a dose of 10 μmol (1.742 mg) per kg immediately after acute spinal cord injury. Ng-nitro-L-arginine methyl ester was applied topically at a dose of 10 μmol (10 mg/kg) immediately after acute spinal cord injury. Cortical somatosensory evoked potentials were recorded before injury and 1 min, 15 min, 30 min, and 60 min after injury. Physiological parameters were followed before, during, and 1 h post injury. Light and electron microscopic analysis was performed in all of the groups. In contrast to group 1, the edema of perineural, axoplasm, or surrounding tissue, the thickening of walls of the arterioles and venules, and the degeneration in myelinated axons in groups 2 and 3 were well observed. However, no differences between group 2 and group 3 occurred. Electronic Publication     

体感诱发电位评价家兔脊髓冲击伤模型的神经机能变化

目的 探讨脊髓冲击伤前后的体感诱发电位的变化,评价家兔神经机能的改变程度.方法 应用改良霍普金森杠杆设备根据冲击波的压力不同(0.40 MPa,0.60 MPa,0.80 MPa)建立不同损伤程度的胸T9-T10脊髓冲击伤模型,12 h后用体感诱发电位仪分别计测家兔脊髓冲击伤前后的体感诱发电位,利用分析软件对诱发电位P...     

Experimental spinal epidural abscess: a pathophysiological model in the rabbit

To define the pathophysiology of spinal cord dysfunction associated with spinal epidural abscess formation, we developed an experimental model. Spinal epidural abscesses were produced in rabbits by injecting Staphylococcus aureus into the posterior thoracolumbar epidural space under direct vision. Progressive neurological deficits were detected in 18 of 20 animals; severe paraparesis or paraplegia occurred in 75%, and sphincter dysfunction occurred in 55%. Clinical data, including the results of plain spine roentgenography, myelography, and biochemical and bacteriological examination of the cerebrospinal fluid, were recorded. Epidural abscesses with varying degrees of spinal cord compression were confirmed pathologically in 95% of the experimental group. Spinal cord white matter changes included vacuolization, loss of myelin, and axonal swelling. The gray matter of the spinal cords was relatively preserved. There was no microscopic evidence of thrombosis or vasculitis in the major blood vessels supplying the spinal cords. Histopathological changes detected in the spinal cords were more consistent with direct compression of neural tissue than with infarction. The progressive clinical course and the histopathological changes in the spinal cord after compression by abscess closely resembled those of experimental compression of the spinal cord by epidural neoplasm.