Soma size and oxidative enzyme activity in normal and chronically stimulated motoneurones of the Cat''s spinal cord

In normal adult cats we measured the density of staining for the activity of succinate dehydrogenase (SDH staining) in ventral horn cells of different sizes. The measurements were restricted to that part of the lumbar ventral horn (L6-L7) which is known to contain motoneurones of the peroneal nerve. A statistically significant tendency was found for the SDH staining to be denser in smaller than in larger neurones within the size range of a motoneurones (soma diameter greater than 40 microns). These results are consistent with recently published evidence for ventral horn cells of rats and qualitatively similar relationships between size and SDH staining have also been observed among skeletal muscle fibres (confirmed for mixed muscle of cat in present study). In hindlimb muscles, size as well as SDH staining are known to be markedly activity-dependent. We tested whether this is the case for peroneal motoneurones as well by analyzing the effects of chronic nerve stimulation on the properties of neurones within the appropriate region of the ventral horn. Prior to the final acute experiment, these cats had been subjected to a left-side dorsal rhizotomy and hemispinalization. By aid of a portable mini-stimulator, the left-side common peroneal nerve was activated by repetitive pulses during 50% of total time per day (intra-activity rate: 10, 20 or 40 Hz). After 8 weeks of such treatment, cell sizes as well as the densities of SDH staining showed hardly any differences between peroneal ventral horn cells of the experimental and control sides of the spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spinal canal narrowing during simulated frontal impact

Between 23 and 70% of occupants involved in frontal impacts sustain cervical spine injuries, many with neurological involvement. It has been hypothesized that cervical spinal cord compression and injury may explain the variable neurological profile described by frontal impact victims. The goals of the present study, using a biofidelic whole cervical spine model with muscle force replication, were to quantify canal pinch diameter (CPD) narrowing during frontal impact and to evaluate the potential for cord compression. The biofidelic model and a sled apparatus were used to simulate frontal impacts at 4, 6, 8, and 10 g horizontal accelerations of the T1 vertebra. The CPD was measured in the intact specimen in the neutral posture (neutral posture CPD), under static sagittal pure moments of 1.5 Nm (pre-impact CPD), during dynamic frontal impact (dynamic impact CPD), and again under static pure moments following each impact (post-impact CPD). Frontal impact caused significant (P<0.05) dynamic CPD narrowing at C0-dens, C2-C3, and C6-C7. The narrowest dynamic CPD was observed at C0-dens during the 10 g impact and was 25.9% narrower than the corresponding neutral posture CPD. Interpretation of the present results indicate that the neurological symptomatology reported by frontal impact victims is most likely not due to cervical spinal cord compression. Cord compression due to residual spinal instability is also not likely.     

Idiopathic Spinal Cord Herniation as a Treatable Cause of Progressive Brown-Sequard Syndrome

Idiopathic spinal cord herniation is a rare spinal cord disorder caused by spinal cord prolapse through a adural defect. It is a curable disease, so early detection is of particular importance. We report a 38-year-old woman with Brown-Sequard syndrome which was caused by the thoracic spinal cord herniation. Her weakness was almost completely resolved after surgical management, which emphasizes the importance of early diagnosis and surgical management in this rare disease entity.     

Effect of the free radical scavenger MCI-186 on spinal cord reperfusion after transient ischemia in the rabbit

Objective: Paraplegia remains a serious complication of aortic operations. The production of free radicals during reperfusion after transient ischemia is believed to induce secondary spinal neuronal injury, resulting in paraplegia. The aim of the present study was to clarify the protective effect and method of administration of antioxidants on the neurological and histological outcome in the animal model for reperfusion injury after transient spinal cord ischemia. Methods: New Zealand white rabbits underwent surgical exposure of the abdominal aorta that was clamped for 15 minutes to achieve spinal cord ischemia. Group A animals received two 10 mg/kg doses of 3-methyl-l-phenyl-2-pyrazolin-5-one (MCI-186) at the time of release of the aortic clamp and 30 minutes later. In group B, MCI-186, 5 mg/kg, was given three times, at the time of aorta clamp release, 30 minutes and 12 hours later. In group C (control group), one dose of vehicle was administered. Neurological status was assessed using modified Tarlov’s score until 168 hours after operation. Spinal cord sections were examined microscopically to determine the extent of ischemic neuronal damage. Results: Groups A and B animals had better neurological function than group C (p(0.001). In contrast, group C animals exhibited paraplegia or paraparesis with marked neuronal necrosis. The number of surviving neurons within examined sections of the spinal cord was significantly greater in group B than in group C (p(0.001). Conclusion: In a 15-minute ischemia-reperfusion model using rabbits, systemic repetitious administration of MCI-186, a free radical scavenger, was found to have a protective effect on the spinal cord neurons both neurologically and histologically. We postulate that the drug minimizes the delayed neuronal cell death for reperfusion injury after transient ischemia by reducing the free radical molecules. Moreover, it was thought that we could protect delayed neuronal cell death more effectively by administering MCI-18612 hours later.     

Mechanisms mediating the brain stem control of somatosensory transmission in the dorsal horn of the cat's spinal cord: an intracellular analysis

Summary The effect of brainstem stimulation was studied on neurones recorded intracellularly in the superficial and deeper laminae of the lumbosacral dorsal horn of the spinal cord in anaesthetised cats. Stimulation in the nucleus locus coeruleus (LC) produced a hyperpolarisation in 4/13 multireceptive neurones and produced a biphasic action consisting of a hyperpolarisation which was followed by a depolarisation in 3/13 neurones. These actions were produced irrespective of whether the multireceptive neurone was located in the superficial or deeper laminae of the dorsal horn. Stimulation failed to produce postsynaptic potentials in the remaining 6/13 multireceptive neurones. The amplitude of hyperpolarisation was increased by the passage of depolarising pulses through the recording microelectrode and decreased by hyperpolarising pulses. Stimulation in other brainstem areas such as, the lateral (FTL), paralemniscal (FTP) and central (FTC) divisions of the tegmental field and the nuclei raphe magnus (NRM) and reticularis magnocellularis (RMc) also hyperpolarised neurones in the dorsal horn. The polarity of hyperpolarisation evoked from some brainstem areas (FTP, FTC, RMc) could be reversed to depolarisation by the passive diffusion of ions from the recording microelectrode containing 3M-KCl. Brainstem (LC, NRM, FTP, FTL) stimulation generated long lasting (700 ms) hyperpolarisation on 4/4 selectively nocireceptive neurones of lamina I. There was, however, no effect on the activity of 5/5 neurones recorded in laminae I/II which in addition to receiving excitatory cutaneous inputs were inhibited by heat stimuli. Stimulation in LC also produced dorsal root potentials (DRPs) and reduced the amplitude of simultaneously recorded excitatory postsynaptic potentials (EPSPs) generated by the activation of primary afferent fibres in 3 multireceptive neurones. It is concluded that inhibition of nociceptive transmission in the spinal cord from LC and other brainstem areas may involve both pre- and postsynaptic mechanisms.     

电针对SNI大鼠痛敏及脊髓相应节段谷氨酸和P物质的影响

目的:探讨电针对神经病理性痛大鼠痛觉过敏以及脊髓谷氨酸和P物质含量的影响。方法:40只SD大鼠,随机分为空白组、假手术组、手术组和电针组(n=10)。采用坐骨神经分支选择性损伤模型,电针"委中"和"环跳"穴,观察其对大鼠机械痛阈和热痛阈的影响,以OPA柱前衍生+HPLC荧光检测和放射免疫分析法测定脊髓相应节段谷氨酸和P物质含量的变化。结果:SNI手术可明显降低大鼠机械痛阈,并且其脊髓相应节段谷氨酸含量明显升高,P物质含量则明显降低;而电针干预后可显著降低大鼠脊髓相应节段谷氨酸的含量,升高P物质含量,并减轻SNI大鼠的机械痛敏状态,进而改善其痛行为。结论:电针干预神经病理性痛的脊髓机制之一可能与其有效的减少大鼠脊髓相应节段谷氨酸和P物质的释放有关。     

同时应用融合和非融合技术治疗创伤性腰椎间盘损伤(附4例临床病例报道及文献复习)

目的观察同时应用融合及非融合技术治疗腰椎间盘损伤的远期疗效,对照该术式与非手术治疗的远期疗效。方法对4例由于急性外伤引起的L4/L5及L5/S1椎间盘损伤患者进行影像学评价。根据生物力学稳定性对病变节段分别采用融合和非融合技术。手术全部经前路腹膜外切口。L5/S1采用椎间融合(自体髂骨 cage植入),L4/L5采用人工椎间盘植入。术后随访4年,摄术后X线正侧位、动力位片,术后2年MRI检查,SF36问卷调查。同期8例患者采用非手术治疗作为对照。结果术后6、12、24、36及48个月X线片显示,融合节段正侧位椎体间无移位,全部患者均有明显的骨性融合。非融合节段人工椎间盘假体位置良好,术后2年MRI显示有正常活动。同期8例非手术治疗患者5例缓解,3例因症状加重实施手术。结论前路融合技术可以有效稳定椎节,缓解腰椎不稳所致的疼痛。人工腰椎间盘植入可以有效地维持放射学稳定性,但不能完全替代正常椎间盘的功能。     

Prenatal diagnosis of Werdnig Hoffmann disease in China

Objective To establish a means for prenatal prediction of spinal muscular atrophy (SMA) through survival motor neuron (SMN) gene deletion analysis and genetic counseling in families with a child affected with SMA.
Methods Genetic analysis for prenatal prediction of Werdnig-Hoffmann disease was performed in a at risk Chinese family by polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) in SMN gene exons 7 and 8.
Results The pregnancy was positive for the homozygous deletion of the SMN gene, thus the fetus was diagnosed as being affected and the pregnancy was terminated.
Conclusion This approach is fast and reliable for DNA-based prenatal diagnosis of Werdnig-Hoffmann disease.     

腰麻硬膜外联合麻醉在全产程中的镇痛效果及对母婴的影响

①目的　探讨腰麻硬膜外联合麻醉在全产程中的镇痛效果以及对母婴的影响。②方法　选择ASAⅠ～Ⅱ级、无禁忌证的单胎头位临产初产妇 30 0例 ,随机分为腰硬组 (腰麻硬膜外联合麻醉 )、硬外组 (硬膜外麻醉 )和对照组 (未用任何麻醉方法 )各 10 0例。行L2～ 3 椎间隙一点穿刺并一次成功。分别观察镇痛效果、起效时间、用药量、副作用、产程、分娩方式及母婴情况。③结果　腰硬组镇痛效果、起效时间以及用药量明显优于硬外组(uc=5 .34,t=16 .92～ 2 9.6 9,P <0 .0 1) ;与对照组比较 ,宫颈扩张加速 ,第一产程明显缩短 ,而第二产程延长 (t =3.34～ 4 8.4 9,P <0 .0 1) ,剖宫产率明显下降 ,而阴道助产率增高 ,胎儿宫内窘迫的发生率下降 (χ2 =6 .82～ 2 0 .35 ,P <0 .0 1)。④结论　腰麻硬膜外联合麻醉用于分娩镇痛优于硬膜外麻醉 ,是一种安全有效、更适合全产程镇痛的麻醉方法。