Electrophysiologic evaluation of peripheral nerve regeneration through allografts immunosuppressed with cyclosporin

A model was designed to evaluate the long-term in vivo electrophysiology of rat peripheral nerve transplants. The application of this model was demonstrated using cyclosporin (CSA) immunosuppression of recipient animals to facilitate peripheral nerve regeneration through nerve allografts. Isogenic Brown Norway (BN) rats [RT1n] were divided into three groups: two received Lewis (LE) rat [RT1l] allografts and one received BN isografts. One allograft recipient group received CSA immunosuppression for the duration of the investigation (150 days). Successful nerve regeneration in the isograft and the immunosuppressed allograft recipient groups was determined by immunohistochemical methods and serial in vivo electrophysiologic techniques to measure nerve conduction velocity and evoked compound muscle action potential amplitude. Statistical analysis of these results indicate that: (a) CSA immunosuppression of peripheral nerve allograft recipients facilitates peripheral nerve regeneration which is indistinguishable from isograft recipient controls at the functioning axon level; and (b) in vivo electrophysiologic monitoring in this model is particularly useful for long term peripheral nerve transplantation studies permitting serial assessment of regeneration with little morbidity.     

The electrophysiological effect of dextrose 5% in water on single-shot peripheral nerve stimulation

When performing regional anesthesia, a small volume of local anesthetic or normal saline abolishes a motor response induced by a low current (0.5 mA). In this case series we describe the electrophysiological effect of a nonconducting (dextrose 5% in water, D5W) injectate on a motor response elicited by low current electrical stimulation. Twenty-nine peripheral nerve blocks were performed in 20 patients using insulated needles. Each needle was primed with D5W. The needle was advanced towards the target nerve until corresponding motor responses were observed using a current of 0.5 mA or less. Once the needle position was optimally placed, 1 mL of D5W was injected followed by a predetermined dose of local anesthetic. The effects of the injectates (D5W and local anesthetic) on the motor response were observed at all needle insertion sites. In all cases, the motor response was at least maintained or augmented (96%) immediately after the injection of D5W. All motor responses diminished after the injection of local anesthetic (100%). All blocks were considered clinically successful.     

Direct nerve stimulation for painful peripheral neuropathies

Nineteen patients with chronic pain due to a traumatic peripheral neuropathy were treated by means of implanted nerve stimulation. In 11 (58%) pain was completely relieved and in four (21%) it was reduced sufficiently to discontinue analgesics. The average follow-up was 11.5 months. The technique is described and the failures discussed. The necessity for implanting the stimulator proximally is emphasised.     

Chronic peripheral nerve pain treated with direct electrical nerve stimulation

Chronic somatic peripheral nerve pain was treated prospectively in 24 nonrandomized patients by a program of direct electrical nerve stimulation. Patients qualified for the program if anesthetic (lidocaine) nerve block of the involved cutaneous zone of the peripheral nerve relieved symptoms and transcutaneous electrical nerve stimulation transiently improved and did not exacerbate somatic pain. Results were judged according to a pain score. Patients noted improved sleep and complete absence of the need for narcotic pain medication. On the basis of subjective and objective criteria, 18 patients had good or excellent results and 6 had implant failures. Of the six patients with failures, three failed the trial period and did not have implantation, and three had no significant pain relief and were judged as treatment failures. Three patients had late equipment failure after initial good results. Most patients had some relief of pain, which increased their quality of life and eliminated the need for narcotic analgesia. Direct electrical nerve stimulation should be considered for somatic peripheral nerve pain that has not been ameliorated with other methods. It will reduce, although not necessarily eliminate, pain and pain behavior in most patients.     

Direct effect of electrical stimulation on peripheral nerve evoked activity: implications in pain relief.

Experiments were performed with a peripheral neurostimulator, used clinically for pain relief, on isolated cat cutaneous peripheral nerve to determine the effect of electrical stimulation on components of the compound action potential. The results show that neurostimulation alters the conduction velocity and the amplitude of both the A-alpha and beta and the A-delta waves with the more slowly-conducting A-delta component showing the greatest changes. This direct alteration of peripheral nerve activity distal to the first synapse in the spinal cord might contribute to the mechanism of pain relief.     

Transcutaneous electrical nerve stimulation in chronic pain after peripheral nerve injury

Summary Transcutaneous electrical stimulation was tested in 24 patients with chronic pain following a peripheral nerve injury in an extremity, in 10 patients with a good effect. All of these 10 patients displayed signs of increased sympathetic activity in addition to hyperalgesia. Sympathetic block gave complete freedom from pain. In 14 patients with the same symptomatology but without an increased or with only very slightly increased sympathetic activity, no or an insignificant effect was obtained. Sympathetic block did not relieve the pain in this group. Transcutaneous electrical stimulation should be tried as an alternative to sympathectomy in causalgia major or minor.     

Inducing peripheral sympathetic nerve activity by therapeutic electrical stimulation

PURPOSE: To examine whether the activity of peripheral sympathetic nerves in animals with spinal cord injury can be controlled using therapeutic electrical stimulation. METHODS: The spinal cords of 6 Wistar rats were severed at T12/T13 disk level and were given continuous therapeutic electrical stimulation. Microneurography was used to record sympathetic nerve activity at 24, 48, and 72 hours after severing the spinal cord. RESULTS: Integrated values of muscle sympathetic nerve activity after 72 hours of therapeutic electrical stimulation revealed significantly larger potentials on the stimulated side than the non-stimulated side. Skin sympathetic nerve activity showed no difference between the 2 sides. CONCLUSION: Therapeutic electrical stimulation was found to have a facilitatory effect on the muscle sympathetic nerve activity, whereas regulatory function was activated by the sympathetic nerves.     

Electrophysiologic facial nerve monitoring during parotidectomy

Facial nerve monitoring is an adjunctive method available to a surgeon during parotid surgery to assist with the functional preservation of the facial nerve. This review describes the goals, applications, technique, and benefits of electrophysiologic facial nerve monitoring during parotid surgery. A review and analysis of the relevant medical literature related to electrophysiologic facial nerve monitoring during parotid surgery are included. © 2009 Wiley Periodicals, Inc. Head Neck, 2010     

Effects of peripheral nerve stimulation on the blood flow of the spinal cord and the nerve root

Hemodynamic changes in the spinal cord and the nerve root caused by electrical sciatic nerve stimulation in anesthetized dogs were measured with a thermal diffusion method. The electrical stimulation increased the blood flow of the stimulated spinal cord and the nerve root. The conditions of stimulation giving the maximum increase of blood flow were different for the spinal cord and the nerve root. Strong stimulation at a high frequency of 50 to 100 Hz was effective for increasing the blood flow. In the spinal cord, an increase of the local metabolic rate appeared to be important for the blood flow increase. In the nerve root, the sympathetic nerves may have an important effect in the blood flow increase.     

可降解材料对外周神经的毒性作用研究

目的 研究聚乳酸、聚羟基乙酸和壳聚糖等可降解材料对正常外周神经有无毒性作用，为研制组织工程化神经筛选相容性好的支架材料。方法 取15只SD大鼠，随机分成3组，打开坐骨神经外膜后，分别将聚乳酸、聚羟基乙酸和壳聚糖植入神经束之间。术后7周取材，观察坐骨神经组织结构的变化以及材料在神经组织内引起的异物反应。结果各组的神经干内均有纤维结缔组织轻度增生，但神经束的形态结构无明显变化；各种材料周围均有纤维假膜形成，假膜内有淋巴细胞和巨噬细胞浸润，而包裹壳聚糖的假膜最厚，细胞浸润最明显。结论 聚乳酸、聚羟基乙酸和壳聚糖对外周神经均无毒性，可作为组织工程化神经的支架材料，但壳聚糖引起的异物反应较聚乳酸和聚羟基乙酸明显。     

经颅磁刺激和局部电刺激促进周围神经再生的组织学研究

目的　研究和比较经颅磁刺激和局部电刺激促进周围神经再生的组织学变化。方法　建立 2 0只大鼠坐骨神经损伤模型后 ,分别用经颅磁刺激动物头颅正上方 2cm处 (相当于运动皮层 ,为经颅磁刺激组 ) ,和直流点送电刺激坐骨神经缝合口近端 (局部电刺激组 )。刺激 2 0min·d-1× 2 0d ;每组 10只大鼠。术后 2 0d取材 ,观察 2组新生神经的形态学变化和有髓神经纤维数目。结果　电刺激组可见许多新生有髓神经纤维 ,但同时可见到有神经纤维髓鞘的退变现象。磁刺激组则有大量新生有髓神经纤维 ,髓鞘较薄但结构完整 ,板层清晰。经颅磁刺激组再生神经纤维的数目明显多于电刺激组 (P <0 0 5 )。结论　经颅磁刺激促进受损周围神经再生和恢复传导功能的作用优于局部电刺激。     

经皮电刺激促进周围神经功能恢复的组织学研究

目的观察并探讨经皮电刺激对大鼠周围神经再生的组织学影响和促进神经损伤后功能恢复的机制。方法用组织学方法观察经皮电刺激对损伤周围神经髓鞘结构和数目的影响,并与对照组进行比较。结果经皮电刺激组可见大量新生髓鞘,髓鞘数目为[(715．29±84．30)个,(?)±s,下同],较对照组(403．67±70．56)个明显增多,两者差异有统计学意义(P＜0．01)。结论经皮电刺激可能具有通过促进Schwann细胞增殖和髓鞘形成,改善受损周围神经再生修复的作用。