Retrograde labeling correlates with motor unit number estimation in rapid‐stretch nerve injury

• Published in: Muscle & nerve 2023-02, Vol.67 (2), p.169-176
• Main Authors: Yeoh, Stewart, Warner, Wesley S., Bromberg, Mark, Mahan, Mark A.
• Format: Article
• Language: English
• Subjects: Abnormalities; Action potential; Action Potentials - physiology; Adenosine; Adenosine triphosphatase; Adenosine Triphosphatases - analysis; Animals; Axon sprouting; Axons; Elastic deformation; Elastic Modulus; Histology; Injuries; Injury prevention; Labeling; Male; Mechanical properties; Mice; Mice, Inbred C57BL; Modulus of elasticity; motor neuron; Motor neurons; Motor Neurons - pathology; motor unit number estimation; Muscle, Skeletal - enzymology; Muscle, Skeletal - innervation; Muscle, Skeletal - pathology; Muscles; Nerves; neuroma; neuroma‐in‐continuity; Neurons; peripheral nerve; Peripheral Nerve Injuries - physiopathology; Recovery; Rupture - physiopathology; stretch injury
• ISSN: 0148-639X; 1097-4598
• DOI: 10.1002/mus.27756

Introduction/Aims Rapid‐stretch nerve injuries represent a substantial treatment challenge. No study has examined motor neuron connection after rapid‐stretch injury. Our objective in this study was to characterize the electrophysiological properties of graded rapid‐stretch nerve injury and assess motor neuron health using retrograde labeling and muscle adenosine triphosphatase (ATPase) histology. Methods Male C57BL/6 mice (n = 6 per group) were rapid‐stretch injured at four levels of severity: sham injury, stretch within elastic modulus, inelastic deformation, and stretch rupture. Serial compound muscle action potential (CMAP) and motor unit number estimation (MUNE) measurements were made for 48 days, followed by retrograde labeling and muscle ATPase histology. Results Elastic injuries showed no durable abnormalities. Inelastic injury demonstrated profound initial reduction in CMAP and MUNE (P