Justin P Chan1, James Clune2, Sameer B Shah3,4, Samuel R Ward3,4, Jeffery D Kocsis5, Tahseen Mozaffar6, Oswald Steward7, Ranjan Gupta1. 1. Department of Orthopaedic Surgery, University of California, Irvine, California. 2. Section of Plastic and Reconstructive Surgery, Yale University School of Medicine, New Haven, Connecticut. 3. Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, California. 4. Department of Bioengineering, University of California, San Diego, La Jolla, California. 5. Department of Neurology, Yale University School of Medicine, New Haven, Connecticut. 6. Department of Neurology, University of California, Irvine, Irvine, California. 7. Reeve-Irvine Research Center, University of California, Irvine, Irvine, California.
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.
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.