Motor neuron-specific RhoA knockout delays degeneration and promotes regeneration of dendrites in spinal ventral horn after brachial plexus injury

Dendrites play irreplaceable roles in the nerve conduction pathway and are vulnerable to various insults.Peripheral axotomy of motor neurons results in the retraction of dendritic arbors,and the dendritic arbor can be re-expanded when reinnervation is allowed.RhoA is a target that regulates the cytoskeleton and promotes neuronal survival and axon regeneration.However,the role of RhoA in dendrite degeneration and regeneration is unknown.In this study,we explored the potential role of RhoA in dendrites.A line of motor neuronal conditional knockout mice was developed by crossbreeding HB9~(Cre+)mice with RhoA~(flox/flox)mice.We established two models for assaying dendrite degeneration and regeneration,in which the brachial plexus was transection or crush injured,respectively.We found that at 28 days after brachial plexus transection,the density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice were slightly decreased compared with that in Cre mice.Dendrites underwent degeneration at 7 and 14 days after brachial plexus transection and recovered at 28–56 days.The density,complexity,and structural integrity of dendrites in the ventral horn of the spinal cord of RhoA conditional knockout mice recovered compared with results in Cre mice.These findings suggest that RhoA knockout in motor neurons attenuates dendrite degeneration and promotes dendrite regeneration after peripheral nerve injury.

Hemodynamic instability following intravenous dexmedetomidine infusion for sedation under brachial plexus block: Two case reports

BACKGROUND Dexmedetomidine(DMED)is frequently used as a sedative in several medical fields.The benefits of DMED include enhanced quality of regional anesthesia,prolonged analgesia,and postoperative opioid-sparing when administered intravenously or perineurally in combination with regional anesthesia.Severe hemodynamic complications,such as profound bradycardia and hypotension,can occur after DMED administration in critically ill patients or overdosage;however,there are few reports of complications with DMED administration following brachial plexus block(BPB).CASE SUMMARY We present two cases of hemodynamic instability that occurred following the initial loading of DMED under supraclavicular BPB.A healthy 29-year-old man without any medical history showed profound bradycardia after receiving a loading dose of DMED 0.9μg/kg for 9 min.DMED administration was promptly stopped,and after receiving a second dose of atropine,the heart rate recovered.A 62-year-old woman with a history of cardiomyopathy became hypotensive abruptly,requiring the administration of inotrope and vasopressors after receiving a reduced loading dose of 0.5μg/kg for 10 min.Half of the recommended loading dose of DMED was administered due to the underlying heart dysfunction.Decrea-sed blood pressure was maintained despite the intravenous administration of ephedrine.With continuous infusion of dopamine and norepinephrine,the vital signs were maintained within normal ranges.Inotropic and vasopressor support was required for over 6 h after the initial loading dose of DMED.CONCLUSION DMED administration following BPB could trigger hemodynamic instability in patients with decreased cardiac function as well as in healthy individuals.

Axillary Vessels and Brachial Plexus Traumas in Abidjan: Lesional Aspects and Surgical Difficulties

Introduction-Objectives: Through the presentation of epidemiological, anatomo-clinical and surgical aspects, we report our experience in the management of traumatic axillary lesions. Materials and Methods: A descriptive retrospective study was based on the medical records of patients who suffered vascular axillary and/or brachial plexus trauma and who underwent surgical repair at the Abidjan Cardiology Institute from January 2008 to June 2022. Epidemiological, anatomo-clinical and surgical data were studied. Results: Thirty-four medical files belonging to 33 men and one woman, aged 32 on average, were collected. The circumstances of occurrence were dominated by the stab wound (n = 22). The combinations of injuries were as follows: associated involvement of the axillary artery and vein (n = 4);isolated involvement of axillary artery (n = 3);isolated involvement of the axillary vein (n = 2);associated involvement of the axillary artery and brachial plexus (n = 17);associated involvement of the axillary artery and vein and brachial plexus (n = 08). Anatomic lesions included acute arterial lesions (n = 29) and arteriovenous fistula (n = 1) and false aneurysms (n = 4). All patients were operated on under general anesthesia;vascular repair included direct suturing (n = 16), arterial and venous bypass using a long saphenous graft (n = 9), prosthetic arterial bypass (n = 5) and prosthetic flattening-graft (n = 4). Brachial plexus surgery consisted of an end-to-end anastomosis of each transected bundle in all cases (n = 25). The medium-term postoperative course was marked by success without functional sequelae in 88.24% of cases (n = 30) and by the persistence of distal paralysis of the thoracic limb after 6 months in 05.88% (n = 2) of all patients, i.e., 8% of patients who presented with brachial plexus injury. Conclusion: The concomitant surgical treatment of these axillary vascular and nerve lesions has given good results. However, if paralysis of the thoracic limb persists after 6 to 12 months, the patient should be referred to a specialist in brachial plexus surgery.

Electroacupuncture attenuates neuropathic pain after brachial plexus injury

Electroacupuncture has traditionally been used to treat pain, but its effect on pain following brachial plexus injury is still unknown. In this study, rat models of an avulsion injury to the left brachial plexus root （associated with upper-limb chronic neuropathic pain） were given electroacupuncture stimulation at bilateral Quchi （LIll）, Hegu （LI04）, Zusanli （ST36） and Yanglingquan （GB34）. After electroacupuncture therapy, chronic neuropathic pain in the rats＇ upper limbs was significantly attenuated. Immunofluorescence staining showed that the expression of β-endorphins in the arcuate nucleus was significantly increased after therapy. Thus, experimental findings indi- cate that electroacupuncture can attenuate neuropathic pain after brachial plexus injury through upregulating β-endorphin expression.

Human amniotic epithelial cell transplantation for the repair of injured brachial plexus nerve: evaluation of nerve viscoelastic properties

The transplantation of embryonic stem cells can effectively improve the creeping strength of nerves near an injury site in animals. Amniotic epithelial cells have similar biological properties as em-bryonic stem cells; therefore, we hypothesized that transplantation of amniotic epithelial cells can repair peripheral nerve injury and recover the creeping strength of the brachial plexus nerve. In the present study, a brachial plexus injury model was established in rabbits using the C6root avulsion method. A suspension of human amniotic epithelial cells was repeatedly injected over an area 4.0 mm lateral to the cephal and caudal ends of the C6 brachial plexus injury site （1 × 106 cells/mL, 3μL/injection, 25 injections） immediately after the injury. The results showed that the decrease in stress and increase in strain at 7,200 seconds in the injured rabbit C6 brachial plexus nerve were mitigated by the cell transplantation, restoring the viscoelastic stress relaxation and creep properties of the brachial plexus nerve. The forepaw functions were also signiifcantly improved at 26 weeks after injury. These data indicate that transplantation of human amniotic epithelial cells can effec-tively restore the mechanical properties of the brachial plexus nerve after injury in rabbits and that viscoelasticity may be an important index for the evaluation of brachial plexus injury in animals.

Magnetic resonance imaging with three-dimensional fast imaging employing steady-state acquisition with phase-cycled and short T1 inversion recovery pulse sequence for evaluating brachial plexus injury

There is a large amount of fat in the postganglionic segment of the brachial plexus nerve.The use of short T1 inversion recovery pulse sequence may improve signal strength of the brachial plexus postganglionic segment.The present study revealed that the combination of three-dimensional fast imaging employing steady-state acquisition with phase-cycled and short T1 inversion recovery pulse sequence clearly displayed the anatomical morphology and structure of the brachial plexus nerve,together with maximum intensity projection,volume rendering and other three-dimensional reconstruction techniques.Our results suggested that this method is also suitable for providing accurate assessment and diagnosis of the site,severity and scope of brachial plexus injury.

Total brachial plexus injury： contralateral C7 root transfer to the lower trunk versus the median nerve

Contralateral C7（cC7） root transfer to the healthy side is the main method for the treatment of brachial plexus root injury. A relatively new modification of this method involves cC7 root transfer to the lower trunk via the prespinal route. In the current study, we examined the effectiveness of this method using electrophysiological and histological analyses. To this end, we used a rat model of total brachial plexus injury, and cC7 root transfer was performed to either the lower trunk via the prespinal route or the median nerve via a subcutaneous tunnel to repair the injury. At 4, 8 and 12 weeks, the grasping test was used to measure the changes in grasp strength of the injured forepaw. Electrophysiological changes were examined in the flexor digitorum superficialis muscle. The change in the wet weight of the forearm flexor was also measured. Atrophy of the flexor digitorum superficialis muscle was assessed by hematoxylin-eosin staining. Toluidine blue staining was used to count the number of myelinated nerve fibers in the injured nerves. Compared with the traditional method, cC7 root transfer to the lower trunk via the prespinal route increased grasp strength of the injured forepaw, increased the compound muscle action potential maximum amplitude, shortened latency, substantially restored tetanic contraction of the forearm flexor muscles, increased the wet weight of the muscle, reduced atrophy of the flexor digitorum superficialis muscle, and increased the number of myelinated nerve fibers. These findings demonstrate that for finger flexion functional recovery in rats with total brachial plexus injury, transfer of the cC7 root to the lower trunk via the prespinal route is more effective than transfer to the median nerve via subcutaneous tunnel.

Small-worldness of brain networks after brachial plexus injury: a resting-state functional magnetic resonance imaging study

Research on brain function after brachial plexus injury focuses on local cortical functional reorganization,and few studies have focused on brain networks after brachial plexus injury.Changes in brain networks may help understanding of brain plasticity at the global level.We hypothesized that topology of the global cerebral resting-state functional network changes after unilateral brachial plexus injury.Thus,in this cross-sectional study,we recruited eight male patients with unilateral brachial plexus injury（right handedness,mean age of 27.9±5.4years old）and eight male healthy controls（right handedness,mean age of 28.6±3.2）.After acquiring and preprocessing resting-state magnetic resonance imaging data,the cerebrum was divided into 90 regions and Pearson’s correlation coefficient calculated between regions.These correlation matrices were then converted into a binary matrix with affixed sparsity values of 0.1–0.46.Under sparsity conditions,both groups satisfied this small-world property.The clustering coefficient was markedly lower,while average shortest path remarkably higher in patients compared with healthy controls.These findings confirm that cerebral functional networks in patients still show smallworld characteristics,which are highly effective in information transmission in the brain,as well as normal controls.Alternatively,varied small-worldness suggests that capacity of information transmission and integration in different brain regions in brachial plexus injury patients is damaged.

Nerve transfer helps repair brachial plexus injury by increasing cerebral cortical plasticity

In the treatment of brachial plexus injury, nerves that are functionally less important are transferred onto the distal ends of damaged crucial nerves to help recover neuromuscular function in the target region. For example, intercostal nerves are transferred onto axillary nerves, and accessory nerves are transferred onto suprascapular nerves, the phrenic nerve is transferred onto the musculocutaneous nerves, and the contralateral C7 nerve is transferred onto the median or radial nerves. Nerve transfer has become a major method for reconstructing the brachial plexus after avulsion injury. Many experiments have shown that nerve transfers for treatment of brachial plexus injury can help reconstruct cerebral cortical function and increase cortical plasticity. In this review article, we summarize the recent progress in the use of diverse nerve transfer methods for the repair of brachial plexus injury, and we discuss the impact of nerve transfer on cerebral cortical plasticity after brachial plexus injury.

Transplantation of human amniotic epithelial cells repairs brachial plexus injury:pathological and biomechanical analyses

A brachial plexus injury model was established in rabbits by stretching the C6 nerve root. Imme- diately after the stretching, a suspension of human amniotic epithelial cells was injected into the injured brachial plexus. The results of tensile mechanical testing of the brachial plexus showed that the tensile elastic limit strain, elastic limit stress, maximum stress, and maximum strain of the injured brachial plexuses were significantly increased at 24 weeks after the injection. The treatment clearly improved the pathological morphology of the injured brachial plexus nerve, as seen by hematoxylin eosin staining, and the functions of the rabbit forepaw were restored. These data indicate that the injection of human amniotic epithelial cells contributed to the repair of brachial plexus injury, and that this technique may transform into current clinical treatment strategies.

Contralateral C7 transfer combined with acellular nerve allografts seeded with differentiated adipose stem cells for repairing upper brachial plexus injury in rats

Nerve grafting has always been necessary when the contralateral C7 nerve root is transferred to treat brachial plexus injury. Acellular nerve allograft is a promising alternative for the treatment of nerve defects, and results were improved by grafts laden with differentiated adipose stem cells. However, use of these tissue-engineered nerve grafts has not been reported for the treatment of brachial plexus injury. The aim of the present study was to evaluate the outcome of acellular nerve allografts seeded with differentiated adipose stem cells to improve nerve regeneration in a rat model in which the contralateral C7 nerve was transferred to repair an upper brachial plexus injury. Differentiated adipose stem cells were obtained from Sprague-Dawley rats and transdifferentiated into a Schwann cell-like phenotype. Acellular nerve allografts were prepared from 15-mm bilateral sections of rat sciatic nerves. Rats were randomly divided into three groups: acellular nerve allograft, acellular nerve allograft + differentiated adipose stem cells, and autograft. The upper brachial plexus injury model was established by traction applied away from the intervertebral foramen with micro-hemostat forceps. Acellular nerve allografts with or without seeded cells were used to bridge the gap between the contralateral C7 nerve root and C5–6 nerve. Histological staining, electrophysiology, and neurological function tests were used to evaluate the effect of nerve repair 16 weeks after surgery. Results showed that the onset of discernible functional recovery occurred earlier in the autograft group first, followed by the acellular nerve allograft + differentiated adipose stem cells group, and then the acellular nerve allograft group;moreover, there was a significant difference between autograft and acellular nerve allograft groups. Compared with the acellular nerve allograft group, compound muscle action potential, motor conduction velocity, positivity for neurofilament and S100, diameter of regenerating axons, myelin sheath thickness, and density of myelinated fibers were remarkably increased in autograft and acellular nerve allograft + differentiated adipose stem cells groups. These findings confirm that acellular nerve allografts seeded with differentiated adipose stem cells effectively promoted nerve repair after brachial plexus injuries, and the effect was better than that of acellular nerve repair alone. This study was approved by the Animal Ethics Committee of the First Affiliated Hospital of Sun Yat-sen University of China(approval No. 2016-150) in June 2016.

Electroacupuncture stimulation of the brachial plexus trunk on the healthy side promotes brain-derived neurotrophic factor mRNA expression in the ischemic cerebral cortex of a rat model of cerebral ischemia/reperfusion injury

A rat model of cerebral ischemia/reperfusion was established by suture occlusion of the left middle cerebral artery. In situ hybridization results showed that the number of brain-derived neurotrophic factor mRNA-positive cells in the ischemic rat cerebral cortex increased after cerebral ischemia/ reperfusion injury. Low frequency continuous wave electroacupuncture （frequency 2-6 Hz, current intensity 2 mA） stimulation of the brachial plexus trunk on the healthy （right） side increased the number of brain-derived neurotrophic factor mRNA-positive cells in the ischemic cerebral cortex 14 days after cerebral ischemia/reperfusion injury. At the same time, electroacupuncture stimulation of the healthy brachial plexus truck significantly decreased neurological function scores and alleviated neurological function deficits. These findings suggest that electroacupuncture stimulation of the brachial plexus trunk on the healthy （right） side can greatly increase brain-derived neurotrophic factor mRNA expression and improve neurological function.

Phrenic nerve transfer to the musculocutaneous nerve for the repair of brachial plexus injury: electrophysiological characteristics

Phrenic nerve transfer is a major dynamic treatment used to repair brachial plexus root avulsion. We analyzed 72 relevant articles on phrenic nerve transfer to repair injured brachial plexus that were indexed by Science Citation Index. The keywords searched were brachial plexus injury, phrenic nerve, repair, surgery, protection, nerve transfer, and nerve graft. In addition, we per-formed neurophysiological analysis of the preoperative condition and prognosis of 10 patients undergoing ipsilateral phrenic nerve transfer to the musculocutaneous nerve in our hospital from 2008 to 201 3 and observed the electromyograms of the biceps brachii and motor conduc-tion function of the musculocutaneous nerve. Clinically, approximately 28% of patients had brachial plexus injury combined with phrenic nerve injury, and injured phrenic nerve cannot be used as a nerve graft. After phrenic nerve transfer to the musculocutaneous nerve, the regener-ated potentials ifrst appeared at 3 months. Recovery of motor unit action potential occurred 6 months later and became more apparent at 12 months. The percent of patients recovering ‘ex-cellent’ and ‘good’ muscle strength in the biceps brachii was 80% after 18 months. At 12 months after surgery, motor nerve conduction potential appeared in the musculocutaneous nerve in seven cases. These data suggest that preoperative evaluation of phrenic nerve function may help identify the most appropriate nerve graft in patients with an injured brachial plexus. The func-tional recovery of a transplanted nerve can be dynamically observed after the surgery.

Effects of brachial plexus injury anastomosis simulation on biomechanical properties of adult brachial plexus

BACKGROUND： Previous studies of peripheral nerve mechanical properties in animals have utilized one-dimensional drawing methods. OBJECTIVE： To analyze the effects of brachial plexus injury anastomosis simulation on biomechanical properties of adult brachial plexus by observing tensile mechanical properties, stress relaxation, and creep deformation of the brachial plexus in normal human cadavers and brachial plexus from simulated brachial plexus injury anastomosis samples. DESIGN, TIME AND SETTING： The in vitro experiment was performed at the Mechanics Experimental Center, Jilin University, China from April to May 2007. MATERIALS： A total of six adult, male cadavers, who had died from acute trauma, and were aged 20-29 years, were supplied by the Research Room of Anatomy, Medical Department, Jilin University, China. AG-10TA Universal Material Testing Machine （Shimadzu, Japan） was used in this study. METHODS： A total of 36 samples of fresh brachial plexus were collected from the cadavers, comprising 12 C5 nerve roots, 12 C6 nerve roots at the left and right sides of the superior truck, and 12 C7 nerve roots at the middle truck. The C5 and C6 nerve roots were processed into 50 samples and the C7 nerve roots into 24 samples. A total of 36 C5 and C6 nerve root samples were randomly assigned to a non-surgery control group （n = 18） and brachial plexus injury anastomosis simulation group （n = 18）. Brachial plexus injury simulation anastomosis samples underwent an incision in the middle, and then received anastomosis. Samples in both groups underwent a tension test at 5 mm/min on the AG-10TA universal material testing machine. A total of 24 samples from the C6 superior trunk and C7 middle trunk of the brachial plexus were subjected to stress relaxation and creep tests. Test duration was 7 200 seconds. A total of 100 data points were collected and analyzed using a normalization method. MAIN OUTCOME MEASURES： The following parameters were measured： tension maximum displacement, maximum load, maximum stress, maximum strain and stress-strain curve, stress relaxation at 7 200 seconds, creep deformation at 7 200 seconds, stress relaxation, and creep curve in the non-surgery control group and brachial plexus injury simulation anastomosis group. RESULTS： The tension maximum load of brachial plexus was （140.36 ± 30.50） N, maximum stress was （10.67 ± 2.52） MPa, maximum displacement was （7.78 ± 1.48） mm, and maximum strain was （31.64 ± 5.32）% in the non-surgery control group. The tension maximum load of brachial plexus was （93.23 ± 20.65） N, maximum stress was （7.09 ± 1.57） MPa, maximum displacement was （6.13 ± 0.86） mm,and maximum strain was （24.55 ± 3.45）% in the brachial plexus injury simulation anastomosis group. The above-mentioned indices were greater in the non-surgery control group than in the brachial plexus injury simulation anastomosis group （P 〈 0.01）. Stress relaxation at 7 200 seconds was 2.07 MPa and 2.11 MPa, respectively, in the non-surgery control and brachial plexus injury simulation anastomosis groups. Creep deformation at 7 200 seconds was 4.68% and 3.52%, respectively, in the non-surgery control and brachial plexus injury simulation anastomosis groups. CONCLUSION： Decreased tension maximum load, maximum displacement, maximum stress, maximum strain, and creep deformation at 7 200 seconds affected the biomechanical properties of the brachial plexus following brachial plexus injury.

Restoration and protection of brachial plexus injury: hot topics in the last decade

Brachial plexus injury is frequently induced by injuries, accidents or birth trauma. Upper limb function may be partially or totally lost after injury, or left permanently disabled. With the de- velopment of various medical technologies, different types of interventions are used, but their effectiveness is wide ranging. Many repair methods have phasic characteristics, i.e., repairs are done in different phases. This study explored research progress and hot topic methods for pro- tection after brachial plexus injury, by analyzing 1,797 articles concerning the repair of brachial plexus injuries, published between 2004 and 2013 and indexed by the Science Citation Index database. Results revealed that there are many methods used to repair brachial plexus injury, and their effects are varied. Intervention methods include nerve transfer surgery, electrical stimula- tion, cell transplantation, neurotrophic factor therapy and drug treatment. Therapeutic methods in this field change according to the hot topic of research.

Calcitonin gene-related peptide in anterior and posterior horns of spinal cord after brachial plexus injury

BACKGROUND： The changes of calcitonin gene-related peptide （CGRP） expression are closely associated with peripheral nerve injury, whereas it should be further investigated whether the damage of central nerve can lead to the changes of CGRP expression, and whether it is associated with the neural regeneration and repair. OBJECTIVE： To observe the changing law of CGRP expression in the anterior and posterior horns of spinal cord following brachial plexus injury. DESIGN： A randomized controlled trial. SETTINGS： Department of Anatomy, Yunyang Medical College; Department of Anatomy, Basic Medical College, Sun Yat-sen University. MATERIALS： Sixty-five adult male SD rats of clean degree, weighing 180 - 220 g, provided by the experimental animal center of the Basic Medical College, Sun Yat-sen University, were randomly divided into control group （n =5） and experimental group （n =60）, and the latter was subdivided into three damage groups： avulsion of anterior root group （n =20）, disjunction of posterior root group （n =20） and transection of spinal cord group （n =20）. Diaminobenzidine （DAB） chromogen, rabbit anti-CGRP polyclonal antibody were the products of Sigma Company; Leica image analytical apparatus was produced by QUIN Company （Germany）; Histotome by Sigma Company. METHODS： The experiments were carried out in the Department of Anatomy, Basic Medical College, Sun Yat-sen University from September 2004 to March 2005. Three kinds of models of brachial plexus injury were established： In the avulsion of anterior root group, right C7 anterior root was avulsed, and the distal nerve residual root was transected. In the disjunction of posterior root group, right C7 anterior root was avulsed and right C5 - T1 posterior horns were cut to block the sensory afferent pathway. In the transection of spinal cord group, right C7 anterior root was avulsed and C5-6 segments of right spinal cord were semi-transected to block the cortical descending pathway. In the control group, C5 - T1 vertebral plates were prayed open, and then the skin was sutured. The C7 segments of spinal cord were removed on the 1^st, 3^rd, 7^th and 14^th days postoperatively respectively, and the CGRP expressions in the anterior and posterior horns of spinal cord were determined and analyzed using immunohistochemical method and image analysis. MAIN OUTCOME MEASURES： ① Number of CGRP immuno-positive motor neurons in the anterior horn of spinal cord; ② Total area ofCGRP immuno-positive fibers in the posterior horn of spinal cord. RESULTS： All the 65 rats were involved in the analysis of results. ① Number of CGRP immuno-positive motor neurons in the anterior horn of spinal cord： CGRP immuno-positive motor neurons could be observed in the anterior horns of C7 spinal cord in the control group and damage groups, the neurons had big cell body with stained cytoplasm, appeared as brown granules, and mainly distributed in the ventral lateral anterior horn of spinal cord. On the Ist day postoperatively, the number of CGRP positive neurons was obviously higher in the in the avulsion of anterior root group than in the control group （P 〈 0.01）, whereas obviously lower in the disjunction of posterior root group than in the control group （P 〈 0.01）, and there was no obvious difference between the transection of spinal cord group and the control group （P 〉 0.05）. On the 7^th day, the numbers of CGRP positive neurons in the damage groups were obviously higher than that in the control group （P 〈 0.01）, also obviously different from those on the 1^st day in the same group respectively （P 〈 0.01）. On the 14^th day, the number of CGRP positive neurons in the disjunction of posterior root group was decreased, but there was no obvious difference as compared with that in the control group, whereas those in the avulsion of anterior root group and transection of spinal cord group were still obviously higher than that in the control group （P 〈 0.01）. The number of CGRP positive neurons was the most in the avulsion of anterior root group, followed by the transection of spinal cord group, and the least in the disjunction of posterior root group, and there were significant differences among them （P 〈 0.01）. ② Total area of CGRP immuno-positive fibers in the posterior horn of spinal cord： Dense CGRP immuno-positive nerve fibers distributed in the layers Ⅰ and Ⅱ of the C7 posterior horn of spinal cord in the control group. On the 1^st day postoperatively, the total areas of CGRP positive fibers in the avulsion of anterior root group and transection of spinal cord group were obviously larger than that in the control group （P 〈 0.01）, whereas there was no obvious difference between the disjunction of posterior root group and control group. On the 7^th day, the CGRP expression in the posterior horn of spinal cord decreased to the lowest level in the disjunction of posterior root group, whereas there were no obvious differences in the avulsion of anterior root group and transection of spinal cord group as compared with that in the control group （P 〉 0.05）. On the 14^th day, the area continued to decrease in the avulsion of anterior root group and transection of spinal cord group, and it was obviously lower in the transection of spinal cord group than in the control group （P 〈 0.01）, and it was slightly increased in the disjunction of posterior root group as compared with that on 7^th day, but still obviously lower than that in the control group （P 〈 0.01）. CONCLUSION： The expression and role of CGRP are in discrepancy in the anterior and posterior horns of spinal cord after brachial plexus injury. The CGRP in anterior horn of spinal cord are derived from the cell body of motor neurons, and may be involved in the repairing mechanism of nerve injury regeneration; Whereas those in the posterior horn are mainly derived from posterior root ganglion, and may be associated with the conduction of noxious stimulations.

Transposition of Branches of Radial Nerve Innervating Supinator to Posterior Interosseous Nerve for Functional Reconstruction of Finger and Thumb Extension in 4 Patients with Middle and Lower Trunk Root Avulsion Injuries of Brachial Plexus

This study aimed to investigate the reconstruction of the thumb and finger extension function in patients with middle and lower trunk root avulsion injuries of the brachial plexus. From April 2010 to January 2015, we enrolled in this study 4 patients diagnosed with middle and lower trunk root avulsion injuries of the brachial plexus via imaging tests, electrophysiological examinations, and clinical confirmation. Muscular branches of the radial nerve, which innervate the supinator in the forearm, were transposed to the posterior interosseous nerve to reconstruct the thumb and finger extension function. Electrophysiological findings and muscle strength of the extensor pollicis longus and extensor digitorum communis, as well as the distance between the thumb tip and index finger tip, were monitored. All patients were followed up for 24 to 30 months, with an average of 27.5 months. Motor unit potentials（MUP） of the extensor digitorum communis appeared at an average of 3.8 months, while MUP of the extensor pollicis longus appeared at an average of 7 months. Compound muscle action potential（CMAP） appeared at an average of 9 months in the extensor digitorum communis, and 12 months in the extensor pollicis longus. Furthermore, the muscle strength of the extensor pollicis longus and extensor digitorum communis both reached grade Ⅲ at 21 months. Lastly, the average distance between the thumb tip and index finger tip was 8.8 cm at 21 months. In conclusion, for patients with middle and lower trunk injuries of the brachial plexus, transposition of the muscular branches of the radial nerve innervating the supinator to the posterior interosseous nerve for the reconstruction of thumb and finger extension function is practicable and feasible.

Evaluation of nerve transfer options for treating total brachial plexus avulsion injury： a retrospective study of 73 participants

Despite recent great progress in diagnosis and microsurgical repair, the prognosis in total brachial plexus-avulsion injury remains unfavorable.Insufficient number of donors and unreasonable use of donor nerves might be key factors. To identify an optimal treatment strategy for this condition, we conducted a retrospective review. Seventy-three patients with total brachial plexus avulsion injury were followed up for an average of 7.3 years. Our analysis demonstrated no significant difference in elbow-flexion recovery between phrenic nerve-transfer （25 cases）, phrenic nerve-graft （19 cases）, intercostal nerve （17 cases）, or contralateral C7-transfer （12 cases） groups. Restoration of shoulder function was attempted through anterior accessory nerve （27 cases）, posterior accessory nerve （10 cases）, intercostal nerve （5 cases）, or accessory ＋ intercostal nerve transfer （31 cases）. Accessory nerve ＋ intercostal nerve transfer was the most effective method. A significantly greater amount of elbow extension was observed in patients with intercostal nerve transfer （25 cases） than in those with contralateral C7 transfer （10 cases）. Recovery of median nerve function was noticeably better for those who received entire contralateral C7 transfer （33 cases） than for those who received partial contralateral C7 transfer （40 cases）. Wrist and finger extension were reconstructed by intercostal nerve transfer （31 cases）. Overall, the recommended surgical treatment for total brachial plexus-avulsion injury is phrenic nerve transfer for elbow flexion, accessory nerve ＋ intercostal nerve transfer for shoulder function, intercostal nerves transfer for elbow extension, entire contralateral C7 transfer for median nerve function, and intercostal nerve transfer for finger extension. The trial was registered at Clinical-Trials.gov （identifier： NCT03166033）.

3.0-T magnetic resonance imaging in children with brachial plexus birth injury

Brachial plexus birth injuries in children are usually diagnosed using 1.5-T magnetic resonance imaging, while the application of high-field magnetic resonance imaging is rarely reported. Therefore, a retrospective comparison of 18 cases of children with brachial plexus injury was performed to investigate the characteristics of 3.0-T magnetic resonance imaging and intraoperative observations. Magnetic resonance examinations in 18 cases of children showed that pseudo-meningocele sensitivity, specificity, accuracy, and positivity rates were 83.3%, 79.6%, 81.1%, and 40.0%, respectively. As for the neuroma and fibrous scar encapsulation, the sensitivity, specificity, accuracy, and positivity rates were 92.9%, 50.0%, 83.3%, and 77.8%, respectively. These results confirm that 3.0-T high-field magnetic resonance imaging can clearly reveal abnormal changes in brachial plexus injury, in which pseudo-meningocele, fibrous scar encapsulation, and neuroma are the characteristic changes of obstetric brachial plexus preganglionic and postganglionic nerve injury.

Differentiation of endogenous neural stem cells in adult versus neonatal rats after brachial plexus root avulsion injury

An experimental model of brachial plexus root avulsion injury of cervical dorsal C5-6 was established in adult and neonatal rats.Real-time PCR showed that the levels of brain-derived neurotrophic factor,nerve growth factor and neurotrophin-3 in adult rats increased rapidly 1 day after brachial plexus root avulsion injury,and then gradually decreased to normal levels by 21 days.In neonatal rats,levels of the three neurotrophic factors were decreased on the first day after injury,and then gradually increased from the seventh day and remained at high levels for an extended period of time.We observed that greater neural plasticity contributed to better functional recovery in neonatal rats after brachial plexus root avulsion injury compared with adult rats.Moreover, immunohistochemical staining showed that the number of bromodeoxyuridine/nestin-positive cells increased significantly in the spinal cords of the adult rats compared with neonatal rats after brachial plexus root avulsion injury.In addition,the number of bromodeoxyuridine/glial fibrillary acidic protein-positive cells in adult rats was significantly higher than in neonatal rats 14 and 35 days after brachial plexus injury.Bromodeoxyuridine/β-tubulin-positive cells were not found in either adult or neonatal rats.These results indicate that neural stem cells differentiate mainly into astrocytes after brachial plexus root avulsion injury.Furthermore,the degree of neural stem cell differentiation in neonatal rats was lower than in adult rats.