The assessment of neuronal plasticity following sciatic nerve injuries in rats using electron microscopy and stereological methods.

The transmission of signals to the cell body from injured axons induces significant alterations in primary sensory neurons located in the ganglion tissue, the site of the perikaryon of the affected nerve fibers. Disruption of the continuity between the proximal and distal ends leads to substantial adaptability in ganglion cells and induces macrophage-like activity in the satellite cells. Research findings have demonstrated the plasticity of satellite cells following injury. Satellite cells work together with sensory neurons to extend the interconnected surface area in order to permit effective communication. The dynamic cellular environment within the ganglion undergoes several alterations that ultimately lead to differentiation, transformation, or cell death. In addition to necrotic and apoptotic cell morphology, phenomena such as histomorphometric alterations, including the development of autophagic vacuoles, chromatolysis, cytosolic degeneration, and other changes, are frequently observed in cells following injury. The use of electron microscopic and stereological techniques for assessing ganglia and nerve fibers is considered a gold standard in terms of investigating neuropathic pain models, regenerative therapies, some treatment methods, and quantifying the outcomes of pharmacological and bioengineering interventions. Stereological techniques provide observer-independent and reliable results, which are particularly useful in the quantitative assessment of three-dimensional structures from two-dimensional images. Employing the fractionator and disector techniques within stereological methodologies yields unbiased data when assessing parameters such as number. The fundamental concept underlying these methodologies involves ensuring that each part of the structure under evaluation has an equal opportunity of being sampled. This review describes the stereological and histomorphometric evaluation of dorsal root ganglion neurons and satellite cells following nerve injury models.

The histomorphological and stereological assessment of rat dorsal root ganglion tissues after various types of sciatic nerve injury.

Peripheral nerve injuries lead to significant changes in the dorsal root ganglia, where the cell bodies of the damaged axons are located. The sensory neurons and the surrounding satellite cells rearrange the composition of the intracellular organelles to enhance their plasticity for adaptation to changing conditions and response to injury. Meanwhile, satellite cells acquire phagocytic properties and work with macrophages to eliminate degenerated neurons. These structural and functional changes are not identical in all injury types. Understanding the cellular response, which varies according to the type of injury involved, is essential in determining the optimal method of treatment. In this research, we investigated the numerical and morphological changes in primary sensory neurons and satellite cells in the dorsal root ganglion 30 days following chronic compression, crush, and transection injuries using stereology, high-resolution light microscopy, immunohistochemistry, and behavioral analysis techniques. Electron microscopic methods were employed to evaluate fine structural alterations in cells. Stereological evaluations revealed no statistically significant difference in terms of mean sensory neuron numbers (p > 0.05), although a significant decrease was observed in sensory neuron volumes in the transection and crush injury groups (p < 0.05). Active caspase-3 immunopositivity increased in the injury groups compared to the sham group (p < 0.05). While crush injury led to desensitization, chronic compression injury caused thermal hyperalgesia. Macrophage infiltrations were observed in all injury types. Electron microscopic results revealed that the chromatolysis response was triggered in the sensory neuron bodies from the transection injury group. An increase in organelle density was observed in the perikaryon of sensory neurons after crush-type injury. This indicates the presence of a more active regeneration process in crush-type injury than in other types. The effect of chronic compression injury is more devastating than that of crush-type injury, and the edema caused by compression significantly inhibits the regeneration process.

Cost-effectiveness analysis of Avance® allograft for the treatment of peripheral nerve injuries in the USA.

Aim: Peripheral nerve injury (PNI) is a debilitating condition with significant associated morbidity, and which places a substantial socioeconomic burden on healthcare systems worldwide. Recently, allograft has emerged as a viable surgical alternative to autograft for the treatment of PNI. This study evaluated the cost effectiveness of allograft (Avance® Nerve Graft) compared with autograft for the peripheral nerve repair, from a US payer perspective. Methods: A Markov cohort model was developed to consider the treatment pathways followed by a patient population undergoing a single transected nerve repair with either allograft, or autograft. The marginal difference in meaningful recovery (MR) (effectiveness), and costs, between the two groups were estimated over a lifetime horizon. Deterministic and probabilistic sensitivity analyses (PSA) were performed to consider the uncertainty surrounding the base-case input parameter values and their effect on the overall incremental cost-effectiveness ratio (ICER). Results: The base-case analysis indicates that there is a small difference in the average probability of MR between the two groups (75.15% vs 70.46%; +4.69% with allograft). Allograft also results in cost savings ($12,677 vs $14,023; -$-1346 with allograft) compared with autograft. Deterministic sensitivity analysis shows that the costs of the initial surgical procedures are the main drivers of incremental cost, but that the intervention is likely to be cost saving compared with autograft regardless of the parameter variations made. Conclusion: The use of allograft with the Avance Nerve Graft has the potential to be a cost-effective alternative to autograft for the surgical treatment of PNI in the USA.

Animal models in peripheral nerve transection studies: a systematic review on study design and outcomes assessment.

Aim: Peripheral nerve injury regeneration studies using animal models are crucial to different pre-clinical therapeutic approaches efficacy evaluation whatever the surgical technique explored. Materials & methods: A 944 articles systematic review on 'peripheral nerve injury in animal models' over the last 9 years was carried out. Results: It was found that 91% used rodents, and only 9% employed large animals. Different nerves are studied, with generated gaps (10,78 mm) and methods applied for regeneration evaluation uniformed. Sciatic nerve was the most used (88%), followed by median and facial nerves (2.6%), significantly different. Conclusion: There has not been a significant scale-up of the in vivo testing to large animal models (anatomically/physiologically closer to humans), allowing an improvement in translational medicine for clinical cases.

[Choosing the right imaging for the diagnostics and assessment of the course of peripheral nerve injuries]. / Die Wahl der richtigen Bildgebung zur Diagnostik und Verlaufsbeurteilung peripherer Nervenverletzungen.

BACKGROUND: Nerve injuries are a frequent problem in routine clinical practice and require intensive interdisciplinary care. OBJECTIVE: The current status of imaging to confirm the diagnosis of nerve injuries is described. The role of high-resolution ultrasound and magnetic resonance imaging (MRI) in the diagnostics and follow-up of peripheral nerve injuries is elaborated. MATERIAL AND METHODS: Review of the current state of imaging to confirm the diagnosis of nerve injuries. RESULTS: Depending on the suspected site of damage, the primary domain of magnetic resonance (MR) imaging (MR neurography) is injuries in the region of the spine, nerve roots, brachial plexus and lumbar plexus, pelvis and proximal thigh. In contrast, in other peripheral nerve lesions of the extremities the advantages of high-resolution nerve ultrasound in a dynamic setting predominate. The MR neurography is indicated here, especially in the frequent bottleneck syndromes and only in very isolated and selected cases. CONCLUSION: In addition to a correct anatomical assignment, the timely decision for a possible intervention and the appropriate concomitant treatment are an important basis for a favorable prognosis of nerve injuries. Imaging techniques should therefore be used early in the diagnostics and follow-up controls of peripheral nerve injuries.

The diagnostic utility of inspiratory-expiratory radiography for the assessment of phrenic nerve palsy associated with brachial plexus injury.

BACKGROUND: The phrenic nerve is commonly injured with trauma to the brachial plexus. Hemi-diaphragmatic paralysis may be well-compensated in healthy individuals at rest but can be associated with persistent exercise intolerance in some patients. This study aims to determine the diagnostic value of inspiratory-expiratory chest radiography compared to intraoperative stimulation of the phrenic nerve for assessing phrenic nerve injury associated with brachial plexus injury. METHODS: Over a 21-year period, the diagnostic utility of three-view inspiratory-expiratory chest radiography for identification of phrenic nerve injury was determined by comparison to intraoperative phrenic nerve stimulation. Multivariate regression analysis was used to identify independent predictors of phrenic nerve injury and having an incorrect radiographic diagnosis. RESULTS: A total of 237 patients with inspiratory-expiratory chest radiography underwent intraoperative testing of phrenic nerve function. Phrenic nerve injury was present in approximately one-fourth of cases. Preoperative chest radiography had a sensitivity of 56%, specificity of 93%, positive predictive negative of 75%, and negative predictive value of 86% for identification of a phrenic nerve palsy. Only C5 avulsion was found to be a predictor of having an incorrect diagnosis of phrenic nerve injury on radiography. CONCLUSION: While inspiratory-expiratory chest radiography has good specificity for detecting phrenic nerve injuries, a high number of false negatives suggest that it should not be relied upon for routine screening of dysfunction after traumatic brachial plexus injury. This is likely multifactorial and relates to variation in diaphragm shape and position, as well as limitations regarding static image interpretation of a dynamic process.

Digital Nerve Injury: Assessment and Treatment.

Undertreated digital nerve injuries may result in sensory deficits and pain. Early recognition and treatment will optimize outcomes, and providers should maintain a high index of suspicion when assessing patients with open wounds. Acute, sharp lacerations may be amenable to direct repair while avulsion injuries or delayed repairs require adequate resection and bridging with nerve autograft, processed nerve allograft, or conduits. Conduits are most appropriate for gaps less than 15 mm, and processed nerve allografts have demonstrated reliable outcomes across longer gaps.

The incidence and management of peripheral nerve injury in England (2005-2020).

Peripheral nerve injury (PNI) is a significant health problem that confers lifelong impact on those injured. Current interventions are purely surgical; however, outcomes remain poor. There is a lack of high-quality epidemiological data that is needed to identify populations involved, current healthcare demands, and ensure resources are distributed to the greatest effect, to reduce the injury burden. METHODS: Anonymized hospital episode statistical (HES) data on admitted patient care was obtained from NHS Digital for all National Health Service (NHS) patients sustaining PNI of all body regions between 2005 and 2020. Total numbers of finished consultant episodes (FCEs) or FCEs/100,000 population were used to demonstrate changes in demographic variables, anatomical locations of injury, mechanisms of injury, speciality, and main operation. RESULTS: There was a mean national incidence of 11.2 (95% CI 10.9, 11.6) events per 100,000 population per year. Males were at least twice as likely (p < 0.0001) to sustain a PNI. Upper limb nerves at or distal to the wrist were most commonly injured. Knife injuries increased (p < 0.0001), whereas glass injuries decreased (p < 0.0001). Plastic surgeons increasingly managed PNI (p = 0.002) as opposed to orthopaedic surgeons (p = 0.006) or neurosurgeons (p = 0.001). There was an increase in neurosynthesis (p = 0.022) and graft procedures (p < 0.0001) during the study period. DISCUSSION: PNI is a significant national healthcare problem predominantly affecting distal, upper limb nerves of men of working age. Injury prevention strategies, improved targeted funding and rehabilitation pathways are needed to reduce the injury burden and improve patient care.

Value of ultrasound assessment for traumatic nerve injury of the upper limb.

AIM OF WORK: The type of traumatic peripheral nerve injury is a key factor for determining optimal treatment. Proper assessment of peripheral nerve injury facilitates appropriate treatment, significantly affects prognosis, and reduces disabilities. This study evaluated ultrasonography (US) to assess upper limb traumatic nerve injuries and compared the US with electrodiagnostic studies as the gold standard. MATERIALS AND METHODS: Participants were 69 adults (57 [83%] men, 12 [17%] women; mean age 36.3 ± 13.5 years) with a total of 96 peripheral nerve injuries (duration of 1 month-3 years). High-frequency US examinations and electro-physiologic studies confirmed upper limb peripheral nerve injury. RESULTS: Nerve discontinuation was diagnosed in 15 (15.6%) nerves; the cross-sectional area was increased in 33 (34.4%) nerves. Of 96 injuries, 54 (56.3%) were median, 24 (25%) were ulnar, and 18 (18.8%) were radial nerves. No statistically significant difference was found between US and electro-physiologic studies for nerve injury diagnosis (p = 0.054). CONCLUSION: No significant differences were found between US and electro-physiologic studies for diagnosis of nerve injuries; however, US was valuable to assess surrounding tissue and supplied muscles. The capabilities to detect nerve injury and associated distal muscular, vascular, and other regional structures position the US as a complementary diagnostic tool.

Functional Gait Assessment Using Manual, Semi-Automated and Deep Learning Approaches Following Standardized Models of Peripheral Nerve Injury in Mice.

Objective: To develop a standardized model of stretch−crush sciatic nerve injury in mice, and to compare outcomes of crush and novel stretch−crush injuries using standard manual gait and sensory assays, and compare them to both semi-automated as well as deep-learning gait analysis methods. Methods: Initial studies in C57/Bl6 mice were used to develop crush and stretch−crush injury models followed by histologic analysis. In total, 12 eight-week-old 129S6/SvEvTac mice were used in a six-week behavioural study. Behavioral assessments using the von Frey monofilament test and gait analysis recorded on a DigiGait platform and analyzed through both Visual Gait Lab (VGL) deep learning and standardized sciatic functional index (SFI) measurements were evaluated weekly. At the termination of the study, neurophysiological nerve conduction velocities were recorded, calf muscle weight ratios measured and histological analyses performed. Results: Histological evidence confirmed more severe histomorphological injury in the stretch−crush injured group compared to the crush-only injured group at one week post-injury. Von Frey monofilament paw withdrawal was significant for both groups at week one compared to baseline (p < 0.05), but not between groups with return to baseline at week five. SFI showed hindered gait at week one and two for both groups, compared to baseline (p < 0.0001), with return to baseline at week five. Hind stance width (HSW) showed similar trends as von Frey monofilament test as well as SFI measurements, yet hind paw angle (HPA) peaked at week two. Nerve conduction velocity (NCV), measured six weeks post-injury, at the termination of the study, did not show any significant difference between the two groups; yet, calf muscle weight measurements were significantly different between the two, with the stretch−crush group demonstrating a lower (poorer) weight ratio relative to uninjured contralateral legs (p < 0.05). Conclusion: Stretch−crush injury achieved a more reproducible and constant injury compared to crush-only injuries, with at least a Sunderland grade 3 injury (perineurial interruption) in histological samples one week post-injury in the former. However, serial behavioral outcomes were comparable between the two crush groups, with similar kinetics of recovery by von Frey testing, SFI and certain VGL parameters, the latter reported for the first time in rodent peripheral nerve injury. Semi-automated and deep learning-based approaches for gait analysis are promising, but require further validation for evaluation in murine hind-limb nerve injuries.

Assessment of main complications of regional anesthesia recorded in an acute pain unit in a tertiary care university hospital: a retrospective cohort

Abstract Background Regional anesthesia has been increasingly used. Despite its low number of complications, they are associated with relevant morbidity. This study aims to evaluate the incidence of complications after neuraxial block and peripheral nerve block. Methods A retrospective cohort study was conducted, and data related to patients submitted to neuraxial block and peripheral nerve block at a tertiary university hospital from January 1, 2011 to December 31, 2017 were analyzed. Results From 10,838 patients referred to Acute Pain Unit, 1093(10.1%) had side effects or complications: 1039 (11.4%) submitted to neuraxial block and 54 (5.2%) to peripheral nerve block. The most common side effects after neuraxial block were sensory (48.5%) or motor deficits (11.8%), nausea or vomiting (17.5%) and pruritus (8.0%); The most common complications: 3 (0.03%) subcutaneous cell tissue hematoma, 3 (0.03%) epidural abscesses and 1 (0.01%) arachnoiditis. 204 of these patients presented sensory or motor deficits at hospital discharge and needed follow-up. Permanent peripheral nerve injury after neuraxial block had an incidence of 7.7:10,000 (0.08%). The most common side effects after peripheral nerve block were sensory deficits (52%) and 21 patients maintained follow-up due to symptoms persistence after hospital discharge. Conclusion Although we found similar incidences of side effects or even lower than those described, major complications after neuraxial block had a higher incidence, particularly epidural abscesses. Despite this, other serious complications, such as spinal hematoma and permanent peripheral nerve injury, are still rare.

Incidence, Risk Factors, Prevention, and Management of Peripheral Nerve Injuries Following Shoulder Arthroplasty.

In this article, the authors review the incidence and causes of iatrogenic peripheral nerve injuries following shoulder arthroplasty and provide preventative measures to decrease nerve injury rate and management options. They describe common direct and indirect causes of injury such as laceration and retractor use versus arm positioning and lengthening, respectively. Preventative measures include an understanding of anatomy and high-risk locations in the shoulder, minimizing extreme ranges of arm motion and utilization of intraoperative nerve monitoring. Lastly, the authors review diagnosis and management of neurologic symptoms including how and when to use electrodiagnostic studies, nerve grafts, transfers, or muscle/tendon transfers.

Nerve regeneration in rat peripheral nerve allografts: An assessment of the role of endogenous neurotrophic factors in nerve cryopreservation and regeneration.

Peripheral nerve injury is a common clinical problem that often leads to significant functional impairment or even complete paralysis. Allograft has been proposed as a potential repair strategy for peripheral nerve injuries. Furthermore, peripheral nerve cryopreservation may result in nearly unlimited supply of grafts. However, the concentration of neurotrophic factors secreted by Schwann cells (SCs) in the local micro-environment after transplantation may not be sufficient for the survival of neuronal soma and axonal regeneration. Here, we investigated the effect of endogenous neurotrophic factors (ENTFs) on nerve regeneration in rats after the allograft of a cryopreserved sciatic nerve. ENTFs were highly expressed in the sciatic nerves pretreated for 14 days. Although the number of surviving cells in the sciatic nerves and their immunogenicity were low in the 14-day group after 4 weeks of cryopreservation, they continued to express high levels of ENTFs in vitro. At 1 week postoperation, the 14-day Allo group showed low plasma levels of interleukin-2, interferon-γ and tumour necrosis factor-alpha and low cellular immune response. At 20 weeks postoperation, nerve regeneration and functional recovery in the 14-day Allo group was similar to that in the fresh isograft group but better than that in the cryopreserved-fresh allograft and fresh allograft groups. Thus, ENTFs were induced in vitro after pretreatment of the sciatic nerve. Following cryopreservation, the sciatic nerves with high levels of ENTFs continued to express high levels of ENTFs in vitro. The immune response after allograft was weak, which promoted recipient nerve regeneration.

Assessment of main complications of regional anesthesia recorded in an acute pain unit in a tertiary care university hospital: a retrospective cohort.

BACKGROUND: Regional anesthesia has been increasingly used. Despite its low number of complications, they are associated with relevant morbidity. This study aims to evaluate the incidence of complications after neuraxial block and peripheral nerve block. METHODS: A retrospective cohort study was conducted, and data related to patients submitted to neuraxial block and peripheral nerve block at a tertiary university hospital from January 1, 2011 to December 31, 2017 were analyzed. RESULTS: From 10,838 patients referred to Acute Pain Unit, 1093(10.1%) had side effects or complications: 1039 (11.4%) submitted to neuraxial block and 54 (5.2%) to peripheral nerve block. The most common side effects after neuraxial block were sensory (48.5%) or motor deficits (11.8%), nausea or vomiting (17.5%) and pruritus (8.0%); The most common complications: 3 (0.03%) subcutaneous cell tissue hematoma, 3 (0.03%) epidural abscesses and 1 (0.01%) arachnoiditis. 204 of these patients presented sensory or motor deficits at hospital discharge and needed follow-up. Permanent peripheral nerve injury after neuraxial block had an incidence of 7.7:10,000 (0.08%). The most common side effects after peripheral nerve block were sensory deficits (52%) and 21 patients maintained follow-up due to symptoms persistence after hospital discharge. CONCLUSION: Although we found similar incidences of side effects or even lower than those described, major complications after neuraxial block had a higher incidence, particularly epidural abscesses. Despite this, other serious complications, such as spinal hematoma and permanent peripheral nerve injury, are still rare.

Ontario wait times for delayed surgical treatment of traumatic peripheral nerve injury.

BACKGROUND: To better understand the occurrence and operative treatment of peripheral nerve injury (PNI) and the potential need for additional resources, it is essential to define the frequency and distribution of peripheral nerve procedures being performed. The objective of this study was to evaluate Ontario's wait times for delayed surgical treatment of traumatic PNI. METHODS: We retrieved data on wait times for peripheral nerve surgery from the Ontario Ministry of Health and Long-Term Care Wait Time Information System. We reviewed the wait times for delayed surgical treatment of traumatic PNI among adult patients (age ≥ 18 yr) from April 2009 to March 2018. Data collected included total cases, mean and median wait times, and demographic characteristics. RESULTS: Over the study period, 7313 delayed traumatic PNI operations were reported, with variability in the case volume distribution across Local Health Integration Networks (LHINs). The highest volume of procedures (2788) was performed in the Toronto Central LHIN, and the lowest volume (< 6) in the Waterloo Wellington and North Simcoe Muskoka LHINs. The population incidence of traumatic PNI requiring surgery was 5.1/10 000. The mean and median wait times from surgical decision to surgical repair were 45 and 27 days, respectively. Both the longest and shortest wait times occurred in LHINs with low case volumes. The provincial target wait time was met in 93% of cases, but women waited significantly longer than men (p < 0.001). CONCLUSION: The provincial distribution of traumatic PNI surgery was variable, and the highest volumes were in the LHINs with large populations. The provincial wait time strategy for traumatic PNI surgery is effective, but women waited longer than men. Precise reporting from all hospitals is necessary to accurately capture and understand the delivery of care after traumatic PNI.

Multifactorial Assessment of Motor Behavior in Rats after Unilateral Sciatic Nerve Crush Injury.

The induction of a peripheral nerve injury is a widely used method in neuroscience for the assessment of repair and pain mechanisms among others. In addition, in the research field of movement disorders, sciatic crush injury has been employed to trigger a dystonia-like phenotype in genetically predisposed DYT-TOR1A rodent models of dystonia. To achieve consistent, reproducible and comparable results after a sciatic nerve crush injury, a standardized method for inducing the nerve crush is essential, in addition to a standardized phenotypical characterization. Attention must be paid not only to the specific assortment of behavioral tests, but also to the technical requirements, the correct execution and consecutive data analysis. This protocol describes in detail how to perform a sciatic nerve crush injury and provides a behavioral test battery for the assessment of motor deficits in rats that includes the open field test, the CatWalk XT gait analysis, the beam walking task, and the ladder rung walking task.

QUANTITATIVE HISTOLOGICAL ASSESSMENT OF SKELETAL MUSCLE HYPOTROPHY AFTER NEUROTOMY AND SCIATIC NERVE REPAIR IN RATS.

Reinnervation of skeletal muscles, wich occurs in time, is considered a factor in preventing muscle atrophy and potentially successful functional recovery. Morphometry of denervated muscles makes it possible to assess the dynamics of muscle atrophy after various methods of repairing of a damaged peripheral nerve. The aim - evaluate histological changes and morphometry of m. gastrocnemius in rats after complete neurotomy and nerve repair techniques. In rats the sciatic nerve was crossed and sutured with 4 epineural sutures, 2 sutures with DuraSeal, and 2 sutures with Tisseel. On the 14th, 30th, and 60th day histological changes of m.gastrocnemius were examined and morphometry was performed based on two parameters: muscle fiber diameter and collagen density. Skeletal muscles morphometry was performed after sciatic nerve neurotomy and subsequent microsurgical repair. Muscle fiber wasting was already detected on the 14th day after epineural suture with DuraSeal, and in the Tisseel group - on the 30th day after sciatic nerve damage. The average diameter of muscle fibers in the DuraSeal group increased significantly by the day 60 due to the appearance of hypertrophied fibers. In areas of wasting, connective tissue density increased, which did not change quantitatively during the experiment, while the use of DuraSeal and Tisseel delayed the development of fibrosis for up to the 30th day. Application of DuraSeal and Tisseel with epineural suture delays the development of fibrosis and wasting in denervated muscles during the reinnervation period.

Quantitative assessment of intraneural vascular alterations in peripheral nerve trauma using high-resolution neurosonography: technical note.

High-resolution neurosonography (HRNS) has become a major imaging modality in assessment of peripheral nerve trauma in the recent years. However, the vascular changes of traumatic lesions have not been quantitatively assessed in HRNS. Here, we describe the vascular-ratio, a novel HRNS-based quantitative parameter for the assessment of intraneural vascular alterations in patients with nerve lesions. N = 9 patients suffering from peripheral nerve trauma were examined clinically, electrophysiologically and with HRNS (SonoSite Exporte, Fuji). Image analyses using Fiji included determination of the established fascicular ratio (FR), the cross-section ratio (CSR), and as an extension, the calculation of a vascular ratio (VR) of the healthy versus damaged nerve and a muscle perfusion ratio (MPR) in comparison to a healthy control group. The mean VR in the healthy part of the affected nerve (14.14%) differed significantly (p < 0.0001) from the damaged part (VR of 43.26%). This coincides with significant differences in the FR and CSR calculated for the damaged part versus the healthy part and the controls. In comparison, there was no difference between VRs determined for the healthy part of the affected nerve and the healthy controls (14.14% / 17.72%). However, the MPR of denervated muscles was significantly decreased compared to the non-affected contralateral controls. VR and MPR serve as additional tools in assessing peripheral nerve trauma. Image analysis and calculation are feasible. Combined with the more morphologic FR and CSR, the VR and MPR provide a more detailed insight into alterations accompanying nerve trauma.

RadioGraphics Update: Functional MR Neurography in Evaluation of Peripheral Nerve Trauma and Postsurgical Assessment.

Editor's Note.-Articles in the RadioGraphics Update section provide current knowledge to supplement or update information found in full-length articles previously published in RadioGraphics. Authors of the previously published article provide a brief synopsis that emphasizes important new information such as technological advances, revised imaging protocols, new clinical guidelines involving imaging, or updated classification schemes. Articles in this section are published solely online and are linked to the original article. ©RSNA, 2021.