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PURPOSE: The aim of this study was to investigate the influence of medial meniscus posterior root avulsion (MMPRA) before and after surgical treatment on the biomechanics of the knee joint, including suture repair forces during daily and crutch-assisted gait movements. METHODS: MMPRA were investigated in eight human cadaver knee joint specimens by a dynamic knee joint simulator with daily (normal gait, gait with additional rotational movement, standing up, sitting down) and rehabilitation-associated movements (crutch-assisted gait with limited flexion range of motion [30°] and 30% [toe-touch weight-bearing, TTWB] and 50% of body weight [partial weight-bearing, PWB]) with simulated physiologic muscle forces. Each specimen was tested in intact, torn and repaired (transtibial suture) state. The biomechanical parameters were: medial mean contact pressure and area, knee joint kinematics, medial displacement of the posterior meniscus horn and loading on the anchoring suture. RESULTS: Significant reduction of the contact area due to the avulsion was observed in all movements except for PWB and sitting down. MMPRA repair significantly increased the contact areas during all movements, bringing them to levels statistically indistinguishable from the initial state. MMPRA resulted in a medial displacement up to 12.8 mm (sitting down) and could be reattached with a residual displacement ranging from 0.7 mm (PWB) to 5.7 mm (standing up), all significantly (p < 0.001) reduced compared to the torn state. The mean peak anchoring suture load increased from TTWB (77 N), PWB (91 N) to normal gait (194 N), gait rotation (207 N), sitting (201 N; p < 0.01) and to standing up (232 N; p = 0.03). CONCLUSION: Surgical treatment of MMPRA allows restoration of physiological knee joint biomechanics. Crutch-assisted movements reduce the loading of the repair suture, thus likewise the risk for failure. From a biomechanical point of view, crutch-assisted movements are recommended for the early rehabilitation phase after MMPRA repair. LEVEL OF EVIDENCE: Level V.

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Brachial plexus root avulsion (BPRA) injury arises from challenging delivery during childbirth, sports-related incidents, or car accidents, leading to extensive loss of motor neurons (MNs) and subsequent paralysis, including both motor and sensory impairment. Surgical nerve re-implantation cannot effectively restore motor function, and the survival of injured MNs is vital for axon regeneration and re-innervating the target muscles. Therefore, identifying novel molecular targets to improve injured MNs survival is of great significance in the treatment of BPRA injuries. Endothelin-converting enzyme-like 1 (ECEL1), a membrane-bound metallopeptidase, was initially identified as a molecule associated with nerve injuries. Damaged neurons exhibit a significant increase in the expression of ECEL1 following various types of nerve injuries, such as optic nerve injury and sciatic nerve injury. This study aimed to investigate the relationship between ECEL1 overexpression and the survival of injured MNs following BPRA injury. Our results observed a significant elevation in ECEL1 expression in injured MNs and positively correlated with MNs survival following BPRA injury. The transcription of ECEL1 is regulated by the transcription factors c-Jun and ATF3 in the context of BPRA injury, which is consistent with previous other nerve injuries study. In addition, the expression of TrkA gradually decreases in ECEL1-positive MNs and ECEL1 possibly preserves the activity of downstream AKT-GSK3ß pathway of TrkA in injured MNs. In conclusion, our results introduce a promising therapeutic molecular target to assist re-implantation surgery for the treatment of BPRA injury.

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We review a nerve suture method for size-mismatched nerve transfers and report a case series involving patients with brachial plexus injury who underwent intercostal-to-musculocutaneous nerve transfer using this method.

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BACKGROUND: Posttraumatic intradural hematomas of the cervical spine are rare findings that may yield significant neurological deficits if they compress the spinal cord. These compressive hematomas require prompt surgical evacuation. In certain instances, intradural hematomas may form from avulsion of cervical nerve roots. OBSERVATIONS: The authors present the case of a 29-year-old male who presented with right upper-extremity weakness in the setting of polytrauma after a motor vehicle accident. He had no cervical fractures but subsequently developed right lower-extremity weakness. Magnetic resonance imaging (MRI) demonstrated a compressive hematoma of the cervical spine that was initially read as an epidural hematoma. However, intraoperatively, it was found to be a subdural hematoma, eccentric to the right, stemming from an avulsion of the right C6 nerve root. LESSONS: Posttraumatic cervical subdural hematomas require rapid surgical evacuation if neurological deficits are present. The source of the hematoma may be an avulsed nerve root, and the associated deficits may be unilateral if the hematoma is eccentric to one side. Surgeons should be prepared for the possibility of an intradural hematoma even in instances in which MRI appears consistent with an epidural hematoma.

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In the management of brachial plexus birth palsies, the quality of the roots eligible for reconstruction is thought to be a key issue. The aim of the present study was to evaluate the correlations between pathological root examination and motor recovery after brachial plexus reconstructions. Quantitative histopathological analysis of intraneural fibrosis was conducted on 72 nerve transections (40 roots, 18 trunks and 14 suprascapular nerves) in 20 patients. Clinical recovery of targeted muscles after surgery was assessed by standardized functional scores. After a mean follow-up of 32 months, patients with a lower fibrosis rate for the suprascapular nerve had greater global Mallet scores (r = -0.57; p = 0.042) as well as a greater active shoulder flexion (r = -0.66; p = 0.015). Correlations were also found between C6 root and upper trunk fibrosis rate and some of the subsections of the Mallet score, active movement scale for the biceps and active elbow flexion. These results seem to confirm the relevance of intraoperative pathological evaluation of the roots and nerves after neuroma resection to optimally define the reconstruction strategy.Level of evidence: IV.

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Brachial plexus nerve root avulsion results from complete separation of the nerve root from the spinal cord and is one of the most challenging types of neuropathic pain, coinciding with motor, sensory and autonomic deficits. The severe pain and typical impossibility of root reattachment often leads to requests for amputation. Ibogaine is an indole alkaloid producing psychoactive effects through reported actions upon multiple neurotransmitter systems, including NMDA, κ- and µ-opioid receptors and σ2 receptor sites, along with stimulation of neurotrophic factors GDNF and BDNF. In this case report we describe a 53-year-old male with two decades of severe intractable pain due to brachial plexus nerve root avulsion from vehicular trauma who was successfully treated with both high dose inpatient and low dose outpatient administrations of ibogaine. Though promising for future study, the adverse effects of high dose ibogaine administrations may limit tolerability of this saturation protocol to the most refractory cases.

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BACKGROUND: Brachial plexus root avulsion (BPRA), a disabling peripheral nerve injury, induces substantial motoneuron death, motor axon degeneration and denervation of biceps muscles, leading to the loss of upper limb motor function. Acetylglutamine (N-acetyl-L-glutamine, NAG) has been proven to exert neuroprotective and anti-inflammatory effects on various disorders of the nervous system. Thus, the present study mainly focused on the influence of NAG on motor and sensory recovery after BPRA in rats and the underlying mechanisms. METHODS: Male adult Sprague Dawley (SD) rats were subjected to BPRA and reimplantation surgery and subsequently treated with NAG or saline. Behavioral tests were conducted to evaluate motor function recovery and the mechanical pain threshold of the affected forelimb. The morphological appearance of the spinal cord, musculocutaneous nerve, and biceps brachii was assessed by histological staining. Quantitative real-time PCR (qRT‒PCR) was used to measure the mRNA levels of remyelination and regeneration indicators in myocutaneous nerves. The protein levels of inflammatory and pyroptotic indicators in the spinal cord anterior horn were measured using Western blotting. RESULTS: NAG significantly accelerated the recovery of motor function in the injured forelimbs, enhanced motoneuronal survival in the anterior horn of the spinal cord, inhibited the expression of proinflammatory cytokines and pyroptosis pathway factors, facilitated axonal remyelination in the myocutaneous nerve and alleviated atrophy of the biceps brachii. Additionally, NAG attenuated neuropathic pain following BPRA. CONCLUSION: NAG promotes functional motor recovery and alleviates neuropathic pain by enhancing motoneuronal survival and axonal remyelination and inhibiting the pyroptosis pathway after BPRA in rats, laying the foundation for the use of NAG as a novel treatment for BPRA.

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PURPOSE: To compare biomechanical behaviour of the anterior root of the lateral meniscus (ARLM) after a transtibial repair (TTR) and after an in situ repair (ISR), discussing the reasons for the efficacy of the more advantageous technique. METHODS: Eight cadaveric human knees were tested at flexion angles from 0° to 90° in four conditions of their ARLM: intact, detached, reinserted using TTR, and reinserted using ISR. Specimens were subjected to 1000 N of compression, and the contact area (CA), mean pressure (MP), and peak pressure (PP) on the tibial cartilage were computed. For the TTR, traction force on the sutures was registered. RESULTS: ARLM detachment significantly altered contact biomechanics, mainly at shallow flexion. After ISR, differences compared to the healthy group persisted (extension, CA 22% smaller (p = 0.012); at 30°, CA 30% smaller (p = 0.012), MP 21%, and PP 32% higher (both p = 0.017); at 60°, CA 28% smaller (p = 0.012), MP 32%, and PP 49% higher (both p = 0.025). With TTR, alterations significantly decreased compared to the injured group, with no statistical differences from the intact ones observed, except for CA at extension (15% decrease, p = 0.012) and at 30° (12% decrease, p = 0.017). The suture tension after TTR, given as mean(SD), was 36.46(11.75)N, 44.32(11.71)N, 40.38(14.93)N, and 43.18(14.89)N for the four tested flexion angles. CONCLUSIONS: Alterations caused by ARLM detachment were partially restored with both ISR and TTR, with TTR showing better results on recovering CA, MP, and PP in the immediate postoperative period. The tensile force was far below the value reported to cause meniscal cut-out in porcine models.

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OBJECTIVES: Report on a new transfer for the reinnervation of biceps and brachialis muscles after multilevel avulsive injuries of brachial plexus provided at least T1 is viable: the Medial Cord to Musculocutaneous (MCMc) and its variant, the Medial Cord to anterior Upper Trunk (MC-aUT). The MC-aUT is indicated in agenesia of musculocutaneous nerve and when a residual function in the biceps is present. The MCMc transfer would be unfeasible in the former and contraindicated in the latter. METHODS: Three hundred and five consecutive patients, classified according to the quality of hand function, are available for a long-term follow-up after reconstructive surgery. They had multiple cervical root avulsive injuries at two (C5-C6), three (C5-C6-C7) and four (C5-C6-C7-C8) levels. The reinnervation was obtained via an end-to-end transfer from two donor fascicles located in the medial cord (MC) and aimed at the flexor carpi ulnaris or the flexor digitorum profundus. RESULTS: These transfers have no failures and no complications when the hand shows a normal function. In the case of suboptimal conditions of the hand, the technique is more challenging, but still has many satisfactory results. In the four-root avulsive injuries, on the contrary, strong limitations suggest that different strategies should be preferred. EMG shows a reinnervation in both biceps and brachialis muscles and this accounts for the quality of results. Tendon transfers for wrist and finger dorsiflexion, when required, remain unencumbered. DISCUSSION: The procedures are safe, effective and easily feasible. The ideal candidate has a C5-C6 injury and a normal hand function.

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Brachial plexus root avulsion (BPRA) is frequently caused by high-energy trauma including traffic accident and birth trauma, which will induces massive motoneurons (MNs) death as well as loss of motor and sensory function in the upper limb. The death of MNs is attributed to energy deficiency, neuroinflammation and oxidative stress at the injured ventral horn of spinal cord triggered by BPRA injury. It has been reported which aldose reductase (AR), an endogenous enzyme that catalyzes fructose synthesis, positively correlates with the poor prognosis following cerebral ischemic injury, diabetic retinopathy and diabetic peripheral neuropathy. However, the role of AR in BPRA remains unknown. Herein, we used a mouse model and found that in the spinal cord of BPRA mice, the upregulation of AR correlated significantly with (1) an inactivated SIRT1-AMPK-mTOR pathway and disrupted autophagy; (2) increased byproducts accumulation of lipid peroxidation metabolism and neuroinflammation; and (3) increased MNs death. Furthermore, our results demonstrated the role of AR in BPRA injury whereby the absence of AR (AR knockout mice, AR-/-) prevented the hyper-neuroinflammation and disrupted autophagy as well as motor neuron death caused by BPRA injury. Finally, we further demonstrate that AR inhibitor epalrestat is neuroprotective against BPRA injury by increasing autophagy level, alleviating neuroinflammation and rescuing MNs death in mice. Collectively, our data demonstrate that the AR upregulation in the spinal cord is an important factor contributing to autophagy disruption, neuroinflammation and MNs death following brachial plexus roots avulsion in mice. Our study also provides a promising therapy drug to assist re-implantation surgery for the treatment of BPRA.

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BACKGROUND: Patients often experience strong shooting pains after spinal root avulsion. The efficacy of spinal cord stimulation (SCS) for this type of pain is inconsistent; however, dorsal root entry zone (DREZ) lesioning (DREZ-lesion) has often proven to be an effective treatment modality. The authors report two cases in which DREZ-lesion was performed to treat pain after spinal root avulsion after implantation of SCS, but the operations were challenging due to strong adhesions. OBSERVATIONS: The authors present two cases of patients with pain after spinal root avulsion in whom SCS implantation was only temporarily effective. Patients complained of persistent and paroxysmal shooting pains in the upper extremities. SCS removal and DREZ-lesion were performed, but adhesions in the epidural and subdural space contacting the leads were strong, making it difficult to expose the DREZ. LESSONS: Although adhesions around the spinal cord can be caused by trauma, the authors believe that in these cases, the adhesions could have been caused by the SCS leads. There are few previous reports confirming the efficacy of SCS in treating pain after spinal root avulsion; therefore, caution is required when considering SCS implantation.

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Lumbosacral spinal root avulsion (LSRA) is a severe nerve injury that results in devastating dysfunction in the lower limb. Circular ribonucleic acids (circRNAs) have been reported to be implicated in a variety of diseases. However, the role of circRNAs in LSRA remains unclear. Here, we performed RNA sequencing (RNA-seq) to determine circRNA expression profiles in a rat LSRA model and further investigated their potential functions and the underlying mechanisms by bioinformatic analyses and in vitro experiments. In all, 1708 circRNAs were found to be differentially expressed in spinal cord tissues after LSRA (|fold change| ≥ 2 and p < 0.05), with 591 up-regulated 1117 down-regulated. Meanwhile, 2263 mRNAs were also indentified to be differentially expressed, of which 1471 were upregulated and 792 were downregulated. Eight randomly selected circRNAs and mRNA were successfully verified to be consistent the RNA-seq results by quantitative real-time polymerase chain reaction. Functional analyses based on gene ontology and Kyoto Encyclopedia of Genes and Genomes predicted the potential roles of differentially expressed circRNAs and mRNAs in LSRA, and circRNA/miRNA/mRNA interaction networks revealed that circRNA_7025, a down-regulated circRNA in LSRA, was targeted by two neuronal apoptosis-related miRNAs, rno-miR-1224 and rno-miR-326-5p. Further in vitro experiments revealed that circRNA_7025 protected against oxygen-glucose deprivation induced neuronal apoptosis via the circRNA_7025/miR-1224/miR-326-5p axis. In summary, our results revealed circRNA expression profiles and their potential functions in LSRA. These findings improve our understanding of the pathogenic mechanisms involved in LSRA and might enable us to identify new molecular targets for LSRA.

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Background: N6-methyladenosine (m6A) is the most prevalent modification in mRNAs but its role in lumbosacral nerve root avulsion (LSRA) remains elusive. Materials & methods:Mettl3 expression and global m6A level were detected by qPCR, western blot and immunostaining. Altered m6A-tagged transcript profiles were revealed by methylated RNA immunoprecipitation and RNA sequencing. Results:Mettl3 and global m6A level were upregulated in spinal cord tissues of LSRA rats. In all, 1087 m6A peaks were differentially modified by m6A, of which 654 were upregulated and 433 downregulated. Biological functions of these transcripts and the hypermethylated or hypomethylated transcripts were also identified. Conclusion: Our findings revealed a profound function of m6A modification in LSRA, which provides new insights into its pathogenesis.

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BACKGROUND: Recent studies have indicated that epigallocatechin gallate (EGCG) benefits a variety of neurological insults. This study was performed to investigate the neuroprotective effect of EGCG after brachial plexus root avulsion in SD rats. METHODS: One hundred twenty SD rats were randomized into the following three groups: an EGCG group, an Avulsion group, and a Sham group. There were 40 rats in each group. EGCG (100 mg/kg, i.p.) or normal saline was administered to rats immediately following the injuries. The treatment was continued from day 1 to day 7, and the animals were sacrificed on days 3, 7, 14, and 28 post-surgery for the harvesting of spinal cord samples for Nissl staining, immunohistochemistry (caspase-3, p-JNK, p-c-Jun), and western blot analysis (p-JNK, JNK, p-c-Jun, c-Jun). RESULTS: EGCG treatment caused significant increases in the percentage of surviving motoneurons on days 14 and 28 (p<0.05) compared to the control animals. On days 3 and 7 after avulsion, the numbers of caspase-3-positive motoneurons in the EGCG-treated animals were significantly fewer than in the control animals (p<0.05). The numbers of p- JNK-positive motoneurons and the ratio of p-JNK/JNK were no significant differences between the Avulsion group and the EGCG-treated group after injury at any time point. The numbers of p-c-Jun-positive motoneurons and the ratio of p-c-Jun/c-Jun were significantly lower in the EGCG-treated group compared with the Avulsion group at 3d and 7d after injury (p<0.05). CONCLUSION: Our results indicated that motoneurons were protected by EGCG against the cell death induced by brachial plexus root avulsion, and this effect was correlated with inhibiting c-Jun phosphorylation.

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Understanding new modulators of axon regeneration is central to neural repair. Our previous work demonstrated critical roles of atypical cadherin Celsr2 during neural development, including cilia organization, neuron migration and axon navigation. Here, we address its role in axon regeneration. We show that Celsr2 is highly expressed in both mouse and human spinal motor neurons. Celsr2 knockout promotes axon regeneration and fasciculation in mouse cultured spinal explants. Similarly, cultured Celsr2 mutant motor neurons extend longer neurites and larger growth cones, with increased expression of end-binding protein 3 and higher potassium-induced calcium influx. Mice with Celsr2 conditional knockout in spinal motor neurons do not exhibit any behavioural deficits; however, after branchial plexus injury, axon regeneration and functional forelimb locomotor recovery are significantly improved. Similarly, knockdown of CELSR2 using shRNA interference in cultured human spinal motor explants and motor neurons increases axonal fasciculation and growth. In mouse adult spinal cord after root avulsion, in mouse embryonic spinal cords, and in cultured human motor neurons, Celsr2 downregulation is accompanied by increased levels of GTP-bound Rac1 and Cdc42, and of JNK and c-Jun. In conclusion, Celsr2 negatively regulates motor axon regeneration and is a potential target to improve neural repair.

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Foot drop is a common clinical gait impairment characterized by the inability to raise the foot or toes during walking due to the weakness of the dorsiflexors of the foot. Lumbar spine disorders are common neurogenic causes of foot drop. The accurate prognosis and treatment protocols of foot drop are not well delineated in the scientific literature due to the heterogeneity of the underlying lumbar spine disorders, different severities, and distinct definitions of the disease. For translational purposes, the use of animal disease models could be the best way to investigate the pathogenesis of foot drop and help develop effective therapeutic strategies for foot drops. However, no relevant and reproducible foot drop animal models with a suitable gait analysis method were developed for the observation of foot drop symptoms. Therefore, the present study aimed to develop a ventral root avulsion (VRA)-induced foot drop rat model and record detailed time-course changes of gait pattern following L5, L6, or L5 + L6 VRA surgery. Our results suggested that L5 + L6 VRA rats exhibited changes in gait patterns, as compared to sham lesion rats, including a significant reduction of walking speed, step length, toe spread, and swing phase time, as well as an increased duration of the stance phase time. The ankle kinematic data exhibited that the ankle joint angle increased during the mid-swing stage, indicating a significant foot drop pattern during locomotion. Time-course observations displayed that these gait impairments occurred as early as the first-day post-lesion and gradually recovered 7-14 days post-injury. We conclude that the proposed foot drop rat model with a video-based gait analysis approach can precisely detect the foot drop pattern induced by VRA in rats, which can provide insight into the compensatory changes and recovery in gait patterns and might be useful for serving as a translational platform bridging human and animal studies for developing novel therapeutic strategies for foot drop.

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BACKGROUND: The imaging and electrodiagnostic (EDX) characteristics of traumatic brachial plexus injury (TBPI) are incompletely reported. OBJECTIVES: To describe the epidemiological, clinical, and EDX characteristics of TBPIs in a series of cases in dogs and cats; to determine the association between clinical data, EDX findings, and clinical outcomes; and to assess the sensitivity and specificity of EDX studies to classify nerve lesions. ANIMALS: One hundred and seventy-five dogs and 51 cats with TBPI and EDX exploration of radial nerve, ulnar nerve, or both nerves. METHODS: Retrospective case series. All medical records were searched for dogs and cats presenting with TBPIs that underwent EDX exploration. Epidemiological, clinical, EDX, and follow-up data were extracted. Association between clinical data, EDX findings, and clinical outcomes was explored. RESULTS: Forty-six percent of affected animals were injured before 2 years of age and 57% of dogs weighed more than 20 kg. The radial compound muscle action potential (CMAP) amplitude for dogs and cats that had clinical improvement was higher than in animals without improvement (4.3 mV [0-23.6] vs 0 mV [0-2.4], respectively, P = .02). A discriminating radial CMAP amplitude threshold value of 5 mV had a specificity of 93% (95% CI [80-100]) to predict recovery. CONCLUSIONS AND CLINICAL IMPORTANCE: Electrodiagnostic studies, particularly measurement of radial CMAP amplitude, are valuable diagnostic tests to refine the prognosis of these animals.

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Artemisinin (ART), a well-known antimalarial medicine originally isolated from the plant Artemisia annua, exerts neuroprotective effects in the nervous system owing to an antioxidant effect. Here, we determined whether ART is capable of inhibiting the oxidative stress to enhance motoneuronal (MN) survival to promote motor function recovery of rats following brachial plexus root avulsion (BPRA) with reimplantation surgery. Rats following BPRA and reimplantation were subcutaneously injected with 500 µL of PBS or 16 mg/mL ART once daily for 7 days after surgery. Terzis grooming test (TGT), histochemical staining, real-time polymerase chain reaction, and Western blot were conducted to determine the recovery of motor function of the upper limb, the survival rate of MNs, the oxidative stress levels in the ventral horn of the spinal cord, the morphology of abnormal musculocutaneous nerve fibers, the remyelination of axons in musculocutaneous nerves, and the degree of bicep atrophy. ART significantly increased TGT score, improved the survival of MNs, inhibited the oxidative stress, ameliorated the abnormal morphology of fibers in the musculocutaneous nerve, promoted the remyelination of axons, and alleviated muscle atrophy. Take together, ART can improve the survival of MNs and axonal remyelination to promote the motor function recovery via inhibiting oxidative stress, suggesting that ART may represent a new approach to the therapy of spinal root avulsion.

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In children suffering from brachial plexus birth injuries (BPBI), one major difficulty concerns intraoperative selection of the roots to be used for reconstruction. Between November 2018 and August 2020, surgical qualitative evaluations and pathological quantitative analyses were conducted on 52 roots and 29 distal neural stumps (trunks, divisions, cords, and nerves distal to the neuroma) in 17 patients who underwent brachial plexus reconstruction. For each root, surgeons rated stump quality as "good", "fair" or "avulsed". Neural sections were then sent to pathology to determine percentage intraneural fibrosis under microscopy. Mean root intraneural fibrosis rates were 30.5% (SD 24.9; range, 0-80%), 46.3% (SD 32.6; range, 0-90%) and 24.6% (SD 23.5; range, 0-80%) in the "good quality", "fair quality" and "avulsed" groups, respectively, with no significant differences between groups. In distal neural stumps, the mean intraneural fibrosis rate was 30.9% (SD 24.7). These findings raise the question of conducting frozen section biopsy of neural stumps after neuroma resection to determine surgical reconstruction strategy.

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OBJECTIVE: The evaluation, treatment, and prognosis of neonatal brachial plexus palsy (NBPP) continues to have many areas of debate, including the use of ancillary testing. Given the continued improvement in imaging, it is important to revisit its utility. Nerve root avulsions have historically been identified by the presence of pseudomeningoceles or visible ruptures. This "all-or-none" definition of nerve root avulsions has many implications for the understanding and management of NBPP, especially as characterization of the proximal nerve root as a potential donor remains critical. This study examined the ability of high-resolution MRI to more specifically define the anatomy of nerve root avulsions by individually examining the ventral and dorsal rootlets as they exit the spinal cord. METHODS: This is a retrospective review of patients who had undergone brachial plexus protocol MRI for clinical evaluation of NBPP at a single institution. Each MR image was independently reviewed by a board-certified neuroradiologist, who was blinded to both established diagnosis/surgical findings and laterality. Each dorsal and ventral nerve rootlet bilaterally from C5 to T1 was evaluated from the spinal cord to its exit in the neuroforamen. Each rootlet was classified as avulsed, intact, or undeterminable. RESULTS: Sixty infants underwent brachial plexus protocol MRI from 2010 to 2018. All infants were included in this study. Six hundred individual rootlets were analyzed. There were 49 avulsed nerve rootlets in this cohort. Twenty-nine (59%) combined dorsal/ventral avulsions involved both the ventral and dorsal rootlets, and 20 (41%) were either isolated ventral or isolated dorsal rootlet avulsions. Of the isolated avulsion injuries, 13 (65%) were dorsal only, meaning that the motor rootlets were intact. CONCLUSIONS: A closer look at nerve root avulsions with MRI demonstrates a significant prevalence (approximately 41%) of isolated dorsal or ventral nerve rootlet disruptions. This finding implies that nerve roots previously labeled as "avulsed" but with only isolated dorsal (sensory) rootlet avulsion can yet provide donor fascicles in reconstruction strategies. A majority (99%) of the rootlets can be clearly visualized with MRI. These findings may significantly impact the clinical understanding of neonatal brachial plexus injury and its treatment.

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