Monitoring of macrophage recruitment enhanced by Toll‐like receptor 4 activation with MR imaging in nerve injury

Introduction: Macrophage recruitment is critical for nerve regeneration after an injury. The aim of this study was to investigate whether ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle‐based MRI could be used to monitor the enhanced macrophage recruitment by Toll‐like receptor 4 (TLR4) activation in nerve injury. Methods: Rats received intraperitoneal injections of either lipopolysaccharide (LPS) or phosphate buffered saline (PBS) or no injection (controls) after a sciatic nerve crush injury. After intravenous injection of the USPIOs (LPS and PBS groups) or PBS (control group), MRI was performed and correlated with histological findings. Results: LPS group showed more remarkable hypointense signals on T2*‐weighted imaging and lower T2 values in the crushed nerves than PBS group. The hypointense signal areas were associated with an enhanced recruitment of iron‐loaded macrophages to the injured nerves. Discussion: USPIO‐enhanced MRI can be used to monitor the enhanced macrophage recruitment by means of TLR4 signal pathway activation in nerve injury. Muscle Nerve 58 : 123–132, 2018     

Determinants of nerve conduction recovery after nerve injuries: Compression duration and nerve fiber types

Introduction: The aims of this study were to determine the influences of: (1) timing of nerve decompression; and (2) nerve fiber types on the patterns of nerve conduction studies (NCS) after nerve injury. Methods: Nerve conduction studies (NCS) were performed on 3 models of nerve injury: (1) crush injury due to transient nerve compression (crush group); (2) chronic constriction injury (CCI), or permanent compression (CCI group); and (3) CCI with removal of ligatures, or delayed nerve decompression (De‐CCI group). Results: There were distinct patterns of NCS recovery. The crush and De‐CCI groups achieved similar motor nerve recovery, better than that of the CCI group. In contrast, recovery of sensory nerves was limited in the CCI and De‐CCI groups and was lower than in the crush group. Conclusions: Immediate relief of compression resulted in the best recovery of motor and sensory nerve conduction. In contrast, delayed decompression restored only motor nerve conduction. Muscle Nerve 52 : 107–112, 2015     

Changes in GABA and GABA(B) receptor expressions are involved in neuropathy in the rat cuneate nucleus following median nerve transection

This study examined the relationship between changes in GABA transmission and behavioral abnormalities after median nerve transection. Following unilateral median nerve transection, the percentage of GABA‐like immunoreactive neurons in the cuneate nucleus and that of GABA_B receptor‐like immunoreactive neurons in the dorsal root ganglion in the injured side decreased and reached a nadir at 4 weeks after median nerve transection. Four weeks after bilateral median nerve transection and intraperitoneal application with saline, baclofen (2 mg kg^?1), or phaclofen (2 mg kg^?1) before unilateral electrical stimulation of the injured median nerve, we investigated the level of neuropeptide Y release and c‐Fos expression in the stimulated side of the cuneate nucleus. The neuropeptide Y release level and the number of c‐Fos‐like immunoreactive neurons in the baclofen group were significantly attenuated, whereas those in the phaclofen group had increased compared to the saline group. These findings indicate that median nerve transection reduces GABA transmission, promoting injury‐induced neuropeptide Y release and consequently evoking c‐Fos expression in cuneate nucleus neurons. Furthermore, this study used the CatWalk method to assess behavioral abnormalities in rats following median nerve transection. These abnormalities were reversed by baclofen treatment. Overall, the results suggest that baclofen treatment block neuropeptide Y release, subsequently lessening c‐Fos expression in cuneate neurons and consequently attenuating neuropathic signal transmission to the thalamus. Synapse, 2012. © 2012 Wiley Periodicals, Inc.     

Median nerve changes following steroid injection for carpal tunnel syndrome

Introduction: Neuromuscular ultrasound is a painless, radiation‐free, high‐resolution imaging modality for assessment of the peripheral nervous system. The purpose of this study was to use neuromuscular ultrasound to assess the changes that occur in the median nerve after steroid injection for carpal tunnel syndrome (CTS). Methods: Ultrasound and nerve conduction studies were performed at baseline and 1 week, 1 month, and 6 months after steroid injection in 19 individuals (29 wrists) with CTS. Results: Significant changes were noted in median nerve cross‐sectional area (P < 0.001), mobility (P = 0.001), and vascularity (P = 0.042) at the distal wrist crease after steroid injection, and the nerve cross‐sectional area correlated with symptom score and electrodiagnostic parameters. Changes in the ultrasonographic parameters were seen within 1 week of injection. Conclusions: These findings suggest neuromuscular ultrasound is potentially helpful for the assessment of individuals undergoing treatment for CTS, as typical changes can be expected after successful treatment injection. Muscle Nerve 44: 25–29, 2011     

损伤神经周围注射自体PRP对周围神经损伤的修复效果观察

目的 探讨损伤神经周围注射自体富血小板血浆(platelet-rich plasma,PRP)对周围神经损伤的修复效果。方法 选取2017年1月-2018年7月于本院接受治疗的周围神经损伤患者130例,随机分为手术组、PRP联合组各65例,手术组患者进行显微外科手术,PRP联合组患者在手术基础上注射自体PRP进行治疗; 用酶联免疫吸附实验法检测血清C反应蛋白(CRP)、肿瘤坏死因子-α(TNF-α)水平,用Western blot法检测胰岛素样生长因子1(IGF-1)、血管内皮生长因子(VEGF)表达水平,并对2组患者神经传导速度、下肢运动功能、基本功能优良率以及肌电图疗效进行检测。结果 治疗1、3、6、12个月后PRP联合组患者CRP、TNF-α水平均低于手术组,IGF-1、VEGF表达水平均高于手术组(P<0.05); 治疗1、3、6、12个月后PRP联合组患者感觉、运动神经传导速度、下肢运动功能评分、基本功能恢复优良率、肌电图愈显率均高于手术组(P<0.05)。结论 在手术治疗的基础上注射自体PRP对周围神经损伤患者进行治疗,能够减轻患者炎性损伤程度,上调IGF-1、VEGF的表达水平,加快神经传导速度,促进患者下肢运动功能恢复     

PEMF fails to enhance nerve regeneration after sciatic nerve crush lesion

Abstract The use of electromagnetic fields has been reported to enhance peripheral nerve regeneration. This study aimed to identify the effects of a prolonged protocol of low‐frequency pulsed electromagnetic field (PEMF) on peripheral nerve regeneration. Thirty‐four male Swiss mice (Mus musculus) were divided into PEMF (n = 17) and control (n = 17) groups. All animals underwent a unilateral sciatic‐crush lesion, and the PEMF group was exposed to a 72‐Hz, 2‐G electromagnetic field for 30 min, five days a week, for three weeks. Functional analysis was carried out weekly. After three weeks, the animals were euthanized, and histological, morphometric, oxidative stress, and TGF‐β1 analyses were performed. Functional analysis showed no differences between the groups. Histological appearance was similar between PEMF and control nerves. Morphometric assessment showed that the PEMF nerves trended toward decreased regeneration. The levels of free radicals were more pronounced in PEMF nerves, but were not associated with an increase in the content of the TGF‐β1/Smad signaling pathway. Prolonged PEMF regimen leads to delayed histological peripheral nerve regeneration and increased oxidative stress but no loss of function recovery.     

Sonographic median nerve change after steroid injection for carpal tunnel syndrome

Introduction: The sonographic changes of the median nerve after steroid injection for carpal tunnel syndrome (CTS) still require investigation. Methods: Sixty‐two patients with CTS were included. The Boston Carpal Tunnel Questionnaire was administered, and ultrasonographic examinations were performed before and at 2, 6, and 12 weeks after steroid injection. At 12 weeks, general improvement was scored on a 6‐point Likert scale. Results: After treatment, the cross‐sectional area (CSA) of the median nerve was significantly reduced at 2‐, 6‐, and 12‐week follow‐ups (for each, P < 0.001, analysis of variance). The “significant improvement” group (n = 39) had a significantly greater reduction in the CSA at the carpal tunnel inlet (P = 0.014) and CSA in the proximal carpal tunnel (P = 0.003) compared with the “little/no improvement” group (n = 23). Discussion: Sonographic measurement of CSA may be considered complementary to the standard clinical evaluation in monitoring of treatment response in patients with CTS. Muscle Nerve 58 : 402–406, 2018     

Properties of the tibialis anterior muscle after treatment with laser therapy and natural latex protein following sciatic nerve crush

Introduction: In this study we evaluated the characteristics of the tibialis anterior muscle after sciatic nerve crush and treatment with low‐level laser therapy (LLLT) or the protein from natural latex (P1). Methods: We studied the following 6 groups of male Wistar rats: control (CG); exposed nerve (EG); injured nerve (IG); injured nerve with LLLT (LG); injured nerve with P1 (PG); and injured nerve with P1 and LLLT (LPG). Results: After 4 weeks, muscle morphology showed improvement in the treated groups; after 8 weeks, the treated groups resembled controls, especially the PG. Morphometry revealed muscle fiber atrophy after nerve injury, with time‐dependent recovery. Histochemical analysis revealed increased intermediate fiber area. The PG was more similar to controls with NADH staining, whereas the LPG more closely resembled controls with SDH staining. Conclusion: Treatment using only P1 proved most efficient, revealing a negative interaction between P1 and LLLT. Muscle Nerve 52 : 869–875, 2015     

嗅鞘细胞移植修复坐骨神经缺损

背景：研究表明,嗅鞘细胞有利于神经元存活并促进轴突再生。 目的：验证局部注射嗅鞘细胞治疗大鼠周围神经损伤的可行性。 方法：体外分离、培养SD大鼠嗅鞘细胞。40只SD大鼠切除坐骨神经1.0 cm,植入异体神经1.0 cm。随机分为2组,嗅鞘细胞组局部注射嗅鞘细胞,生理盐水组局部注射生理盐水。术后3个月检测体感诱发电位及运动诱发电位,光镜、电镜观察神经电生理恢复情况。 结果与结论：电镜观察嗅鞘细胞组大鼠在损伤区有较多神经纤维通过,明显多于生理盐水组(P < 0.01)。嗅鞘细胞组大鼠体感诱发电位及运动诱发电位的潜伏期及波幅明显优于生理盐水组(P < 0.01)。提示局部注射嗅鞘细胞能更好地恢复周围神经损伤后的功能。     

Repair of the musculocutaneous nerve using the vagus nerve as donor by helicoid end‐to‐side technique: an experimental study in rats

Although several donor nerves can be chosen to repair avulsed brachial plexus nerve injury, available nerves are still limited. The purpose of this study is to validate whether the vagus nerve (VN) can be used as a donor. Eighteen Sprague‐Dawley male rats were divided into three groups (n = 6). The right musculocutaneous nerve (McN) was transected with differing subsequent repair. (1) HS‐VN group: a saphenous nerve (SN) graft‐end was helicoidally wrapped round the VN side (epi‐and perineurium was opened) with a 30 ° angle, distal SN end was coapted to the McN with end‐to‐end repair. (2) EE‐PN group: a SN was interpositionally grafted between the transected phrenic nerve (PN) and the McN by end‐to‐end coaptation. (3) Sham control group: McN was transected and not repaired and postoperative vital signs were checked daily. At three months, electrophysiology, tetanic force, wet biceps muscle weight, and histology were evaluated. Every tested mean value in HS‐VN group was significantly greater than the EE‐PN or the sham control groups (p < 0.05 or p < 0.005). The mean recovery ratio of regenerated nerve fibers was 96% and, in HS‐VN group, the mean recovery ratio of CMAP was 79%. No vital signs changed in any group. There was no statistical difference (p > 0.5) between the mean VN nerve‐fiber numbers of the segments proximal (2237 ± 134) and distal (2150 ± 156) to the VN graft‐attachment site. Histological analysis revealed no axon injury or intraneural scarring at any point along the VN. This study demonstrated that VN is a practical and reliable donor nerve for end‐to‐side nerve transfer. © 2017 Wiley Periodicals, Inc.     

Calcitonin pump improves nerve regeneration after transection injury and repair

Introduction: After nerve injury, excessive calcium impedes nerve regeneration. We previously showed that calcitonin improved nerve regeneration in crush injury. We aimed to validate the direct effect of calcitonin on transected and repaired nerve. Methods: Two rat groups (n = 8) underwent sciatic nerve transection followed by direct repair. In the calcitonin group, a calcitonin‐filled mini‐osmotic pump was implanted subcutaneously, with a catheter parallel to the repaired nerve. The control group underwent repair only, without a pump. Evaluation and comparison between the groups included: (1) compound muscle action potential recording of the extensor digitorum longus (EDL) muscle; (2) tetanic muscle force test of EDL; (3) nerve calcium concentration; and (4) nerve fiber count and calcified spot count. Results: The calcitonin pump group showed superior recovery. Conclusions: Calcitonin affects injured and repaired peripheral nerve directly. The calcitonin‐filled mini‐osmotic pump improved nerve functional recovery by accelerating calcium absorption from the repaired nerve. This finding has potential clinical applications. Muscle Nerve 51 : 229–234, 2015     

Miconazole enhances nerve regeneration and functional recovery after sciatic nerve crush injury

Introduction: Improving axonal outgrowth and remyelination is crucial for peripheral nerve regeneration. Miconazole appears to enhance remyelination in the central nervous system. In this study we assess the effect of miconazole on axonal regeneration using a sciatic nerve crush injury model in rats. Methods: Fifty Sprague‐Dawley rats were divided into control and miconazole groups. Nerve regeneration and myelination were determined using histological and electrophysiological assessment. Evaluation of sensory and motor recovery was performed using the pinprick assay and sciatic functional index. The Cell Counting Kit‐8 assay and Western blotting were used to assess the proliferation and neurotrophic expression of RSC 96 Schwann cells. Results: Miconazole promoted axonal regrowth, increased myelinated nerve fibers, improved sensory recovery and walking behavior, enhanced stimulated amplitude and nerve conduction velocity, and elevated proliferation and neurotrophic expression of RSC 96 Schwann cells. Discussion: Miconazole was beneficial for nerve regeneration and functional recovery after peripheral nerve injury. Muscle Nerve 57 : 821–828, 2018     

Combining chitin biological conduits with small autogenous nerves and platelet-rich plasma for the repair of sciatic nerve defects in rats

AimsPeripheral nerve defects are often difficult to recover from, and there is no optimal repair method. Therefore, it is important to explore new methods of repairing peripheral nerve defects. This study explored the efficacy of nerve grafts constructed from chitin biological conduits combined with small autogenous nerves (SANs) and platelet‐rich plasma (PRP) for repairing 10‐mm sciatic nerve defects in rats.MethodsTo prepare 10‐mm sciatic nerve defects, SANs were first harvested and PRP was extracted. The nerve grafts consisted of chitin biological conduits combined with SAN and PRP, and were used to repair rat sciatic nerve defects. These examinations, including measurements of axon growth efficiency, a gait analysis, electrophysiological tests, counts of regenerated myelinated fibers and observations of their morphology, histological evaluation of the gastrocnemius muscle, retrograde tracing with Fluor‐Gold (FG), and motor endplates (MEPs) distribution analysis, were conducted to evaluate the repair status.ResultsTwo weeks after nerve transplantation, the rate and number of regenerated axons in the PRP‐SAN group improved compared with those in the PRP, SAN, and Hollow groups. The PRP‐SAN group exhibited better recovery in terms of the sciatic functional index value, composite action potential intensity, myelinated nerve fiber density, myelin sheath thickness, and gastrectomy tissue at 12 weeks after transplantation, compared with the PRP and SAN groups. The results of FG retrograde tracing and MEPs analyses showed that numbers of FG‐positive sensory neurons and motor neurons as well as MEPs distribution density were higher in the PRP‐SAN group than in the PRP or SAN group.ConclusionsNerve grafts comprising chitin biological conduits combined with SANs and PRP significantly improved the repair of 10‐mm sciatic nerve defects in rats and may have therapeutic potential for repairing peripheral nerve defects in future applications.     

Etifoxine provides benefits in nerve repair with acellular nerve grafts

Introduction: Acellular nerve grafts are good candidates for nerve repair, but the clinical outcome of grafting is not always satisfactory. We investigated whether etifoxine could enhance nerve regeneration. Methods: Seventy‐two Sprague‐Dawley rats were divided into 3 groups: (1) autograft; (2) acellular nerve graft; and (3) acellular nerve graft plus etifoxine. Histological and electrophysiological examinations were performed to evaluate the efficacy of nerve regeneration. Walking‐track analysis was used to examine functional recovery. Quantitative polymerase chain reaction was used to evaluate changes in mRNA level. Results: Etifoxine: (i) increased expression of neurofilaments in regenerated axons; (ii) improved sciatic nerve regeneration measured by histological examination; (iii) increased nerve conduction velocity; (iv) improved walking behavior as measured by footprint analysis; and (v) boosted expression of neurotrophins. Conclusions: These results show that etifoxine can enhance peripheral nerve regeneration across large nerve gaps repaired by acellular nerve grafts by increasing expression of neurotrophins. Muscle Nerve 50:235–243, 2014     

Evaluation of artificial nerve conduit and autografts in peripheral nerve repair in the rat model of sciatic nerve injury

Objective: To investigate the therapeutic effect of artificial nerve conduit in the sciatic nerve injury and repair in the rat model.

Methods: A total of 60 adult male Sprague Dawley rats were evenly randomized into five groups to build the model of sciatic nerve injury and perform the injury repair experiment. The five groups were: group A which was treated with artificial nerve conduit, group B which was treated with common carotid artery (CCA) autograft, group C which was treated with sciatic nerve autograft, group D which was treated with sham operation, and group E as the normal control. The injury was repaired by direct coaptation of the nerve ends. Postoperatively, the rats’ behavior, motor nerve conduction velocity (MNCV), incubation period, amplitude, remaining rate of wet weight of the gastrocnemius muscle, the diameter and section area of the gastrocnemius cell, and the histological changes were assessed. The results were analyzed by one-way ANOVA and two-way ANOVA.

Results: Twelve days postoperatively, 36 rats in groups A, B, and C presented with denervated adermotrophia on the injured ankle. The electrophysiological indicators in groups D and E were constant and similar. The values of MNCV and amplitude were group C > group A > group B, with an increasing tendency. The values of the incubation period were group C < group A < group B with statistical difference (p < 0.05) and showed a decreasing tendency. The wet gastrocnemius muscle in groups D and E showed plump morphology with luster and elasticity. Groups A and C had similar atrophic gastrocnemius muscles and reduced flexibility while the phenomena were more severe in group B. Progressive decrease of the cell diameter and sectional area was observed in groups A, B, and C. The adhesion between the sciatic nerve and the surrounding area in groups A, B, and C had statistical significance (P < 0.05), with group B the most serious.

Conclusions: The results suggest that artificial nerve conduit facilitated functional and morphological regeneration of the nerve. It seemed more effective than CCA but inferior to sciatic nerve autograft in repairing sciatic nerve injury in the rat model.     

Butyrate prevents muscle atrophy after sciatic nerve crush

Introduction: Histone deacetylases (HDACs) have been implicated in neurogenic muscle atrophy, but the mechanisms by which HDAC inhibitors might have beneficial effects are not defined. Methods: We used sciatic nerve crush to determine the effect of butyrate on denervation‐induced gene expression and oxidative stress. Results: Butyrate treatment initiated 3 weeks before injury and continued 1 week after injury increases histone acetylation and reduces muscle atrophy after nerve crush. Butyrate delivered only after nerve crush similarly prevented muscle atrophy. Butyrate had no effect on the increase in histone deacetylase 4 (HDAC4) protein levels following nerve crush but prevented the increase in expression of myogenin, MuRF1, and atrogin‐1. Butyrate did not affect mitochondrial reactive oxygen species production, but it increased antioxidant enzyme activity, reduced proteasome activity, and reduced oxidative damage following nerve injury. Conclusions: These data suggest that HDAC inhibitors are promising pharmacological agents for treating neurogenic muscle atrophy. Muscle Nerve 52: 859–868, 2015     

High dose erythropoietin promotes functional recovery of rats following facial nerve crush

Erythropoietin (Epo) has neuroprotective activity in a variety of settings. Thus, we investigated whether Epo has a role in the functional recovery of rats after facial nerve injury. The right facial nerve of 24 Wistar rats (6 wks old) was crushed twice at the level of the stylomastoid foramen, for 30 s each time, using jeweler’s forceps held perpendicular to the nerve. The left facial nerve did not undergo the surgical lesion. The rats were randomly divided into 4 groups: (group 1) the control group (placebo, treated with saline); and groups treated with Epo at a dose of 1,000 U/kg body weight (group 2), 5,000 U/kg body weight (group 3), and 10,000 U/kg body weight (group 4). The Epo and saline were administered subcutaneously pre-operatively and treatment was repeated every 24 h for the first 2 weeks after the operation. Behavioral recovery from facial paralysis was measured daily, beginning 1 day after surgery, until full recovery of the eye blink reflex and whisker movements were observed. The average recovery times for the full blink reflex and whisker movements were significantly shorter (about 2–3 days) in rats treated with a high dose Epo (5,000, 10,000 U/kg body weight) compared to the placebo-treated rats (p < 0.05). There was no significant difference between low dose Epo-treated rats (1,000 U/kg body weight) and the placebo-treated rats. These results suggest that high dose Epo can promote the functional recovery of rats following facial nerve injury. Further studies are warranted to probe alternative treatment schedules (dose, mode of administration), underlying histological mechanisms and combination treatment with additional neuroprotective factors.     

Acellular nerve allografts in peripheral nerve regeneration: a comparative study

Introduction: Processed nerve allografts offer a promising alternative to nerve autografts in the surgical management of peripheral nerve injuries where short deficits exist. Methods: Three established models of acellular nerve allograft (cold‐preserved, detergent‐processed, and AxoGen‐processed nerve allografts) were compared with nerve isografts and silicone nerve guidance conduits in a 14‐mm rat sciatic nerve defect. Results: All acellular nerve grafts were superior to silicone nerve conduits in support of nerve regeneration. Detergent‐processed allografts were similar to isografts at 6 weeks postoperatively, whereas AxoGen‐processed and cold‐preserved allografts supported significantly fewer regenerating nerve fibers. Measurement of muscle force confirmed that detergent‐processed allografts promoted isograft‐equivalent levels of motor recovery 16 weeks postoperatively. All acellular allografts promoted greater amounts of motor recovery compared with silicone conduits. Conclusion: These findings provide evidence that differential processing for removal of cellular constituents in preparing acellular nerve allografts affects recovery in vivo. Muscle Nerve, 2011     

Nerve hydrodissection for carpal tunnel syndrome: A prospective,randomized, double-blind,controlled trial

Introduction: In this study we explored the efficacy of nerve hydrodissection for mild-to-moderate carpal tunnel syndrome (CTS). Methods: Thirty-four participants were randomly assigned to an intervention group or a control group. One 5-ml dose of normal saline was injected into the intracarpal and subcutaneous regions in subjects of both groups, respectively. The primary outcome measure was the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) score. Secondary outcomes were cross-sectional area of the median nerve and electrophysiological studies. Assessments were performed before the injection and at 1, 2, 3, and 6 months postintervention. Results: Compared with the control group, the intervention group showed significantly greater improvement at the second and third posttreatment months according to BCTQ severity score and at all time-points for cross-sectional area of the median nerve (P < 0.01). Discussion: Our study demonstrates the therapeutic effects of nerve hydrodissection for mild-to-moderate CTS. Muscle Nerve 59 :174–180, 2019     

Delivery of adipose‐derived stem cells in poloxamer hydrogel improves peripheral nerve regeneration

Introduction: Peripheral nerve damage is associated with high long‐term morbidity. Because of beneficial secretome, immunomodulatory effects, and ease of clinical translation, transplantation with adipose‐derived stem cells (ASC) represents a promising therapeutic modality. Methods: Effect of ASC delivery in poloxamer hydrogel was assessed in a rat sciatic nerve model of critical‐sized (1.5 cm) peripheral nerve injury. Nerve/muscle unit regeneration was assessed via immunostaining explanted nerve, quantitative polymerase chain reaction (qPCR), and histological analysis of reinnervating gastrocnemius muscle. Results: On the basis of viability data, 10% poloxamer hydrogel was selected for in vivo study. Six weeks after transection and repair, the group treated with poloxamer delivered ASCs demonstrated longest axonal regrowth. The qPCR results indicated that the inclusion of ASCs appeared to result in expression of factors that aid in reinnervating muscle tissue. Discussion: Delivery of ASCs in poloxamer addresses multiple facets of the complexity of nerve/muscle unit regeneration, representing a promising avenue for further study. Muscle Nerve 58 : 251–260, 2018