Stimulated grip strength measurement: Validation of a novel method for functional assessment

BackgroundReliable measurement of functional recovery is critical in translational peripheral nerve regeneration research. Behavioral functional assessments such as volitional grip strength testing (vGST) are limited by inherent behavioral variability. Isometric tetanic force testing (ITFT) is highly reliable but precludes serial measurements. Combining elements of vGST and ITFT, stimulated grip strength testing (sGST) involves percutaneous median nerve stimulation to elicit maximal tetanic contraction of digital flexors, thereby allowing for consistent measurement of maximal grip strength.MethodsWe measured side‐to‐side equivalence of force using sGST, vGST, and ITFT to determine relative reliability and repeatability. We also performed weekly force measurements following median nerve repair.ResultssGST demonstrated greater reliability and inter‐trial repeatability than vGST and similar reliability to ITFT, with the added benefit of serial measurements.ConclusionssGST is a valid method for assessing functional recovery that addresses the limitations of the currently available modalities used in translational peripheral nerve regeneration research.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151883/1/mus26646.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151883/2/mus26646_am.pd

A simple and robust method for automating analysis of naïve and regenerating peripheral nerves

ABSTRACT: Background Manual axon histomorphometry (AH) is time- and resource-intensive, which has inspired many attempts at automation. However, there has been little investigation on implementation of automated programs for widespread use. Ideally such a program should be able to perform AH across imaging modalities and nerve states. AxonDeepSeg (ADS) is an open source deep learning program that has previously been validated in electron microscopy. We evaluated the robustness of ADS for peripheral nerve axonal histomorphometry in light micrographs prepared using two different methods. Methods Axon histomorphometry using ADS and manual analysis (gold-standard) was performed on light micrographs of naïve or regenerating rat median nerve cross-sections prepared with either toluidine-resin or osmium-paraffin embedding protocols. The parameters of interest included axon count, axon diameter, myelin thickness, and g-ratio. Results Manual and automatic ADS axon counts demonstrated good agreement in naïve nerves and moderate agreement on regenerating nerves. There were small but consistent differences in measured axon diameter, myelin thickness and g-ratio; however, absolute differences were small. Both methods appropriately identified differences between naïve and regenerating nerves. ADS was faster than manual axon analysis. Conclusions Without any algorithm retraining, ADS was able to appropriately identify critical differences between naïve and regenerating nerves and work with different sample preparation methods of peripheral nerve light micrographs. While there were differences between absolute values between manual and ADS, ADS performed consistently and required much less time. ADS is an accessible and robust tool for AH that can provide consistent analysis across protocols and nerve states

Breast cancer management pathways during the COVID-19 pandemic: outcomes from the UK ‘Alert Level 4’ phase of the B-MaP-C study

Abstract: Background: The B-MaP-C study aimed to determine alterations to breast cancer (BC) management during the peak transmission period of the UK COVID-19 pandemic and the potential impact of these treatment decisions. Methods: This was a national cohort study of patients with early BC undergoing multidisciplinary team (MDT)-guided treatment recommendations during the pandemic, designated ‘standard’ or ‘COVID-altered’, in the preoperative, operative and post-operative setting. Findings: Of 3776 patients (from 64 UK units) in the study, 2246 (59%) had ‘COVID-altered’ management. ‘Bridging’ endocrine therapy was used (n = 951) where theatre capacity was reduced. There was increasing access to COVID-19 low-risk theatres during the study period (59%). In line with national guidance, immediate breast reconstruction was avoided (n = 299). Where adjuvant chemotherapy was omitted (n = 81), the median benefit was only 3% (IQR 2–9%) using ‘NHS Predict’. There was the rapid adoption of new evidence-based hypofractionated radiotherapy (n = 781, from 46 units). Only 14 patients (1%) tested positive for SARS-CoV-2 during their treatment journey. Conclusions: The majority of ‘COVID-altered’ management decisions were largely in line with pre-COVID evidence-based guidelines, implying that breast cancer survival outcomes are unlikely to be negatively impacted by the pandemic. However, in this study, the potential impact of delays to BC presentation or diagnosis remains unknown

Methodik, Vorteile, Grenzen und Fallstricke

Immunohistochemistry is one of the methods that enables the detection and visualization of different antigens in cells and tissue sections using specific primary antibodies and an efficient detection system. This method has been used since the 1940s and was primarily published by Coons et al.101 In the last 20 years, immunohistochemistry was dramatically developed into a highly specialized molecular technique combining the principles of immunology, biochemistry and histology and became a very powerful tool in the daily diagnostic histopathology. A large number of diagnostic antibodies are now available to detect and localize a large number of cell and tissue antigens that enable histopathologists to resolve many diagnostic problems and to increase diagnostic certainty. Nevertheless, immunohistochemistry - as any other method - has its own possibilities, limitations and diagnostic pitfalls that are important to know for everyone practicing this method. Based on our experience as a reference laboratory for immunohistochemistry, we initiate this study to analyze the possibilities, limitations and pitfalls of immunohistochemistry as an important diagnostic tool in the daily practice of modern histopathologists. In this work we describe the standardized immunohistochemical technique used in our practice and demonstrate our diagnostic algorithms developed to be used as a guide for the classification of primary tumors and histogenetic identification of metastases of unknown origin. We also describe the most important antibodies used in the daily routine and the rational use of these antibodies with the most informative, labor- and time-saving combinations. We discuss the distribution and the specific expression pattern of the targeted antigens and point out the most characteristic immunoprofiles for a large number of tumors and the diagnostic pitfalls that must be considered to avoid any misinterpretation. Considering the factors mentioned above, we analyze in this study the results of 18000 immunohistochemical stains performed in the past 5 years to study 2907 various tumors using more than 110 specific monoclonal and polyclonal primary antibodies. Depending on the adequate tumor morphology and optimal immunophenotyping, we were able to characterize 2691 out of the 2709 cases examined, while 18 cases remain uncertain and were sent for a second opinion to highly specialized centers. Further 198 cases were only tested to determine the sensitivity of the tumors to specific therapeutic agents. In the same time we were able to revise 37 outside diagnoses, mainly made without or only with limited immunohistochemical study. After the analysis of error sources, we present our conclusions and recommendations to increase the value of immunohistochemistry as an informative diagnostic method. The results obtained confirmed the role of immunohistochemistry as a powerful tool in tumor histopathology; however the experience showed that this powerful method is safe and informative only in experienced and carful hands.Die Immunhistochemie ist eine Methode, die den Nachweis von verschiedenen Antigenen in Zellen und Gewebeschnitten unter Anwendung spezifischer Primärantikörper und Detektionssysteme ermöglicht. Diese Methode wurde schon in den 1940er Jahren angewendet und erstmals von Coons et al. beschrieben. In den letzten 20 Jahren hat sich die Immunhistochemie zu einer leistungsfähigen und hochspezialisierten molekularen Technik entwickelt, indem sie Prinzipien der Immunologie, Biochemie und Histologie kombiniert und so zu einem sehr effektiven Werkzeug in der täglichen Histopathologie geworden ist. Derzeit steht eine große Anzahl von diagnostischen Antikörpern zur Verfügung, die eine Vielzahl von Zell- und Gewebeantigenen erkennen und dazu beitragen, diagnostische Probleme zu lösen und die diagnostische Sicherheit zu erhöhen. Dennoch hat die Immunhistochemie ihre Grenzen und weist Fallstricke auf, die jeder praktisch arbeitende Pathologe kennen sollte. Basierend auf langjährigen Erfahrungen im eigenen Referenzlabor für Immunhistochemie, wurde eine Analyse initiiert, um die Möglichkeiten und Grenzen der Immunhistochemie als wichtiges diagnostisches Rüstzeug in der täglichen Routine der modernen Histopathologie aufzuzeigen. In der Arbeit wird zunächst die standardisierte immunhistochemische Technik beschrieben, die in der eigenen Praxis verwendet wird. Außerdem werden diagnostische Algorithmen entwickelt, die für die Klassifikation von Primärtumoren und Metastasen von Tumoren unbekannter Lokalisation verwendet werden können. Es werden die wichtigsten Antikörper für die Routinediagnostik und Möglichkeiten einer rationellen und arbeitszeitsparenden Anwendung dieser Antikörper beschrieben. Weiterhin werden das Expressionsmuster der untersuchten Antigene und die charakteristischsten Immunprofile für eine große Anzahl von Tumoren dargestellt, um diagnostische Fallstricke und Fehlinterpretationen zu vermeiden. Die Arbeit beruht auf den Ergebnissen von 18000 immunhistochemischen Untersuchungen, die in den letzten 5 Jahren an 2907 Tumoren durchgeführt wurden. Dabei gelangten 110 Antikörper zur Anwendung. Auf der Grundlage einer adäquaten Tumormorphologie und optimalen Immunphänotypisierung, konnten 2691 der 2709 Tumoren charakterisiert werden, während 18 Fälle unklar blieben und zur weiteren Diagnostik an spezialisierte Zentren weitergeleitet wurden. Weitere 198 Fälle wurden nur zur Bestimmung der Empfindlichkeit von Anti-Tumor-Arzneimitteln untersucht (Östrogen-und Progesteronrezeptoren, HER-2 und Tyrosinkinase-Inhibitoren). 347 der 384 außerhalb gestellten Diagnosen konnten bestätigt werden, 37 Diagnosen wurden revidiert. Dieses waren vor allem Fälle, die ohne Immunhistochemie oder mit einer geringen Anzahl immunhistochemischer Marker diagnostiziert wurden. Nach eingehender Fehleranalyse werden Schlussfolgerungen und Empfehlungen präsentiert, die dazu beitragen sollen, den Wert der Immunhistochemie als diagnostische Methode zu erhöhen und die Häufigkeit von diagnostischen Fehlern zu verringern. Die Ergebnisse unterstreichen die Bedeutung der Immunhistochemie als effektive Methode in Tumorpathologie. Dabei hat die Erfahrung gezeigt, dass die Methode nur in gut ausgebildeten Händen sicher und informativ ist

Functional reconstruction of lower extremity nerve injuries

Peripheral nerve injuries (PNI) in the lower extremity are an uncommon but highly morbid condition. Recent advances in our understanding of nerve physiology and microsurgical techniques have inspired renewed faith in nerve surgery and sparked a creative renaissance in the tools, approaches, and reconstructive schemas available to surgeons in the management of lower extremity PNIs. In this article, we review the literature and provide a principles-based approach for the surgical management of lower extremity PNIs with an emphasis on techniques for functional reconstruction after complete nerve injury. General principles in management include early diagnosis with electrodiagnostics and imaging, early surgical exploration, and opting for nerve and tendon transfers when primary reconstruction of the injured nerve is unfavorable (e.g., delayed reconstruction, unavailability of proximal or distal nerve stumps, or long regenerative distance). The goal of functional reconstruction should be to restore independent gait, so understanding the roles of major neuromuscular units during the gait cycle informs the selection of donor nerves and tendons for transfer. Based on these principles and literature to date, specific algorithms for surgical management are presented for femoral, sciatic, tibial, and common peroneal nerves. We recognize limitations of the current literature, namely the predominance of case series evidence, and call for the accrual of more patient data in surgical management of PNIs

Nerve regeneration in vascularized composite allotransplantation: current strategies and future directions

Vascularized composite allotransplantation (VCA) has emerged as a viable treatment option for limb and face reconstruction of severe tissue defects. Functional recovery after VCA requires not only effective immunosuppression, but also consideration of peripheral nerve regeneration to facilitate motor and sensory reinnervation of donor tissue. At the time of transplantation, the donor and recipient nerves are typically coapted in an end-to-end fashion. Following transplantation, there are no therapies available to enhance nerve regeneration and graft reinnervation, and functional outcomes are dependent on the recipients’ innate regenerative capacities. Functional outcomes to date have been promising, but there is still much room for improvement, studies have demonstrated reliable return of protective sensation (pain, thermal, gross tactile), while discriminative sensation and motor function show more inconsistent results. In order to maximize the benefit afforded to the by VCA, we must develop consistent and reliable procedures and therapies to ensure effective nerve regeneration and functional outcomes. New technologies, such as nerve guidance conduits and fibrin glues, and the use of stem cells to facilitate nerve regeneration remain untested in VCA but are proving worthwhile in the context of peripheral nerve repair. VCA presents a unique set of challenges with regards to surgical techniques, postoperative regimen, and health of donor tissue. In this review, we discuss current challenges underlying achievement of nerve regeneration in VCA and discuss novel technologies and approaches to translate nerve regeneration into functional restoration