Effect of continuous spinal anesthesia with ropivacaine on the ultrastructure of spinal cord and nerve roots in rats

To investigate the effects of continuous spinal anesthesia with different concentrations and doses of ropivacaine on the ultrastructure of the spinal cord and nerve roots.Methods Twenty-four male SD rats weighing 220～280 g were anesthetized with intraperitoneal 10% chloral hydrate 300～350 mg/kg.A polyurethane microcatheter was inserted into the lumbar subarachnoid space according to the technique described by Yaksh.An 8 cm catheter segment was left in the subarachnoid space.The animals were randomized to receive normal saline,0.5%,0.75% or 1.0% ropivacaine 40 μl intrathecally 3 times at 1.5 h interval.Six hours after the first intrathecal administration the animals were decaptiated and L 1,2 segment of the spinal cord and nerve roots were immediately removed for electron microscopic examination.Results Electron microscopic examination revealed that in animals which received intrathecal (i.t.) normal saline,0.5% or 0.75% ropivacaine the neurolemma of the nerve roots and the mitochondria and endoplasmic reticulum of the neurons in the spinal cord were intact,while in animals which received i.t. 10.% ropivacaine the neurolemma was stratified and partly disrupted and there were swelling of endoplasmic reticulum and vacuole degeneration.Conclusion Six hours continuous spinal anesthesia with 10.% ropivacaine may be injurious to the spinal cord and nerve roots.12 refs,8 figs,1 tab.

Extradural contralateral S1 nerve root transfer for spastic lower limb paralysis

The current study aims to ascertain the anatomical feasibility of transferring the contralateral S1 ventral root(VR)to the ipsilateral L5 VR for treating unilateral spastic lower limb paralysis.Six formalin-fixed(three males and three females)cadavers were used.The VR of the contralateral S1 was transferred to the VR of the ipsilateral L5.The sural nerve was selected as a bridge between the donor and recipient nerve.The number of axons,the cross-sectional areas and the pertinent distances between the donor and recipient nerves were measured.The extradural S1 VR and L5 VR could be separated based on anatomical markers of the dorsal root ganglion.The gross distance between the S1 nerve root and L5 nerve root was 31.31(±3.23)mm in the six cadavers,while that on the diffusion tensor imaging was 47.51(±3.23)mm in 60 patients without spinal diseases,and both distances were seperately greater than that between the outlet of S1 from the spinal cord and the ganglion.The numbers of axons in the S1 VRs and L5 VRs were 13414.20(±2890.30)and 10613.20(±2135.58),respectively.The cross-sectional areas of the S1 VR and L5 VR were 1.68(±0.26)mm2 and 1.08(±0.26)mm2,respectively.In conclusion,transfer of the contralateral S1 VR to the ipsilateral L5 VR may be an anatomically feasible treatment option for unilateral spastic lower limb paralysis.

Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 m A and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.

Chinese Association for the Study of Pain:Experts consensus on ultrasound-guided injections for the treatment of spinal pain in China(2020 edition)

Spinal pain(SP)is a common condition that has a major negative impact on a patient’s quality of life.Recent developments in ultrasound-guided injections for the treatment of SP are increasingly being used in clinical practice.This clinical expert consensus describes the purpose,significance,implementation methods,indications,contraindications,and techniques of ultrasound-guided injections.This consensus offers a practical reference point for physicians to implement successfully ultrasound-guided injections in the treatment of chronic SP.

A novel extradural nerve transfer technique by coaptation of C4 to C5 and C7 to C6 for treating isolated upper trunk avulsion of the brachial plexus

The study aimed to demonstrate the feasibility of an extradural nerve anastomosis technique for the restoration of a C5 and C6 avulsion of the brachial plexus.Nine fresh frozen human cadavers were used.The diameters,sizes,and locations of the extradural spinal nerve roots were observed.The lengths of the extradural spinal nerve roots and the distance between the neighboring nerve root outlets were measured and compared in the cervical segments.In the spinal canal,the ventral and dorsal roots were separated by the dura and arachnoid.The ventral and dorsal roots of C7 had sufficient lengths to anastomose those of C6.The ventral and dorsal of C4 had enough length to be transferred to those of C5,respectively.The feasibility of this extradural nerve anastomosis technique for restoring C5 and C6 avulsion of the brachial plexus in human cadavers was demonstrated in our anatomical study.

Senegenin inhibits neuronal apoptosis after spinal cord contusion injury

Senegenin has been shown to inhibit neuronal apoptosis,thereby exerting a neuroprotective effect.In the present study,we established a rat model of spinal cord contusion injury using the modified Allen＇s method.Three hours after injury,senegenin（30 mg/g） was injected into the tail vein for 3 consecutive days.Senegenin reduced the size of syringomyelic cavities,and it substantially reduced the number of apoptotic cells in the spinal cord.At the site of injury,Bax and Caspase-3 m RNA and protein levels were decreased by senegenin,while Bcl-2 m RNA and protein levels were increased.Nerve fiber density was increased in the spinal cord proximal to the brain,and hindlimb motor function and electrophysiological properties of rat hindlimb were improved.Taken together,our results suggest that senegenin exerts a neuroprotective effect by suppressing neuronal apoptosis at the site of spinal cord injury.

Preconditioning crush increases the survival rate of motor neurons after spinal root avulsion

In a previous study, heat shock protein 27 was persistently upregulated in ventral motor neurons following nerve root avulsion or crush. Here, we examined whether the upregulation of heat shock protein 27 would increase the survival rate of motor neurons. Rats were divided into two groups： an avulsion-only group （avtflsion of the L4 lumbar nerve root only） and a crush-avulsion group （the L4 lumbar nerve root was crushed 1 week prior to the avulsion）. Immunofluores- cent staining revealed that the survival rate of motor neurons was significantly greater in the crush-avulsion group than in the avulsion-only group, and this difference remained for at least 5 weeks after avulsion. The higher neuronal survival rate may be explained by the upregulation of heat shock protein 27 expression in motor neurons in the crush-avulsion group. Further- more, preconditioning crush greatly attenuated the expression of nitric oxide synthase in the motor neurons. Our findings indicate that the neuroprotective action of preconditioning crush is mediated through the upregulation of heat shock protein 27 expression and the attenuation of neuronal nitric oxide synthase upregulation following avulsion.

Identification of motor and sensory fascicles in peripheral nerve trunk using micro-Raman spectroscopy

BACKGROUND： A variety of methods have been used to identify and distinguish motor and sensory nerves. However, their application is limited clinically due to the complex operation, time consumption, and subjectivity. Raman spectroscopy is a minimally invasive method that provides information about molecular structure and constitutions and has been frequently used for tissue identification. OBJECTIVE： To explore a time-efficient method of identifying motor and sensory fascicles in peripheral nerve trunk using laser micro-Raman spectroscopy.DESIGN, TIME AND SETTING： A comparative observation was performed at the Key Laboratory of Excited States Physics in Chinese Academy of Science, Changchun Branch, from October 2004 to October 2005. MATERIALS： JY-HR800 laser confocal micro-Raman spectrometer was purchased from Jobin-Yvon France; 2060-10 argon ion laser was purchased from Spectra-Physics, USA. METHODS： A total of 32 New Zealand rabbits were selected and sacrificed. The roots of spinal nerves were exposed under an operating microscope, and the anterior and posterior roots, approximately 3-5 mm, were dissociated, and frozen as transverse sections of 30 μm thickness. The sections were examined by micro-Raman spectroscopy. MAIN OUTCOME MEASURES： The specific spectral features of motor and sensory fascicles in the Raman spectra. RESULTS： Sections of the same type of nerve fascicle showed reproducibility with similar spectral features. Significant differences in the spectral properties, such as the intensity and breadth of the peak, were found between motor and sensory fascicles in the frequency regions of 1 088, 1 276, 1 439, 1 579, and 1 659 cm^-1. With the peak intensity ratio of 1.06 （/1276//1439） as a standard, we could identify motor fascicles with a sensitivity of 88%, specificity of 94 %, positive predictive value of 93% and negative predictive value of 88%. In the range of 2 700-3 500 cm^-1, the half-peak width of the motor fascicles was narrow and sharp, while that of the sensory fascicles was relatively wider. A total of 91% of the peak features were in accordance with the identification standard. CONCLUSION： Motor and sensory fascicles exhibit different characteristics in Raman spectra, which are constant and reliable. Therefore, it is an effective method to identify nerve fascicles according to the specific spectrum.

Central projections and connections of lumbar primary afferent fibers in adult rats:effectively revealed using Texas red-dextran amine tracing

Signals from lumbar primary afferent fibers are important for modulating locomotion of the hind-limbs.However,silver impregnation techniques,autoradiography,wheat germ agglutinin-horseradish peroxidase and cholera toxin B subunit-horseradish peroxidase cannot image the central projections and connections of the dorsal root in detail.Thus,we injected 3-k Da Texas red-dextran amine into the proximal trunks of L4 dorsal roots in adult rats.Confocal microscopy results revealed that numerous labeled arborizations and varicosities extended to the dorsal horn from T12–S4,to Clarke＇s column from T10–L2,and to the ventral horn from L1–5.The labeled varicosities at the L4 cord level were very dense,particularly in laminae I–Ⅲ,and the density decreased gradually in more rostral and caudal segments.In addition,they were predominately distributed in laminae I–IV,moderately in laminae V–VⅡ and sparsely in laminae VⅢ–X.Furthermore,direct contacts of lumbar afferent fibers with propriospinal neurons were widespread in gray matter.In conclusion,the projection and connection patterns of L4 afferents were illustrated in detail by Texas red-dextran amine-dorsal root tracing.