Examination of the human motor endplate after brachial plexus injury with two‐photon microscopy

Abstract

Introduction After traumatic nerve injury, neuromuscular junction remodeling plays a key role in determining functional outcomes. Immunohistochemical analyses of denervated muscle biopsies may provide valuable prognostic data regarding clinical outcomes to supplement electrodiagnostic studies. Methods We performed biopsies on nonfunctioning deltoid muscles in two patients after gunshot wounds and visualized the neuromuscular junctions using two‐photon microscopy with immunohistochemistry. Results Although the nerves in both patients showed evidence of acute Wallerian degeneration, some of the motor endplates were intact but exhibited significantly decreased surface area and volume. Both patients exhibited substantial recovery of motor function over several weeks postinjury. Discussion Two‐photon microscopic assessment of neuromuscular junction integrity and motor endplate morphometry in muscle biopsies provided evidence of partial sparing of muscle innervation. This finding supported the clinical judgment that eventual recovery would occur. With further study, this technique may help to guide operative decisionmaking after traumatic nerve injuries.

Human motor endplate remodeling after traumatic nerve injury

“…MEP surface area and volume were quantified using ImageJ (National Institutes of Health) with the 3D Object Counter plug-in using the optical fractionator method. 14 Linear regression analysis was used to investigate any linear relationship between denervated muscle time in months and MEP volume or surface area. Analysis was performed using GraphPad Prism 8.0 (GraphPad Software Inc.).…”

Functional regeneration of the murine neuromuscular synapse relies on long-lasting morphological adaptations

“…Subsequently, nascent poly-innervated NMJs turn into functional mono-innervated NMJs 6 weeks after nerve injury [ 5 ]. The fine-tuning of NMJ reinnervation relies on the ability of tSCs to extend transient cell processes that guide the regenerated motor axons to the denervated postsynaptic domains with high precision to avoid axonal miswiring [ 7 , 8 ]. Indeed, cranial nerves misguiding results in synkinesis of facial muscles [ 9 ].…”

Lesiones del plexo braquial en adultos: Una revisión narrativa de la literatura

“…A motor endplate not stimulated for 18 to 24 months suffers atrophy, resulting in permanent muscle fibrosis and inability to restore its function despite reinnervation. 3 Seddon 4 classified peripheral nerve lesions into three groups: neuropraxia, axonotmesis, and neurotmesis. In neuropraxia-type lesions, the damage results in focal demyelination of the axons.…”

“…Si esta placa motora no recibe estímulos antes de 18 a 24 meses, se atrofia y el músculo sufre fibrosis permanente, no siendo posible restaurar su función a pesar de que sea reinervado. 3…”

“…A motor endplate not stimulated for 18 to 24 months suffers atrophy, resulting in permanent muscle fibrosis and inability to restore its function despite reinnervation. 3…”