Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model

Abstract Background Targeted Muscle Reinnervation (TMR) improves real-time control of EMG-based prostheses by connecting severed nerves to adjacent muscles, creating new EMG signals. However, TMR requires cutting original nerve connections, which can cause denervation atrophy and limit functional re...

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Main Authors: Chunxiao Tang, Yuanheng Li, Xinxian Fan, Jiamei Guo, Yifeng Lin, Yifan Gao, Lin Yang
Format: Article
Language:English
Published: BMC 2025-07-01
Series:Journal of NeuroEngineering and Rehabilitation
Subjects:
Online Access:https://doi.org/10.1186/s12984-025-01666-0
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author Chunxiao Tang
Yuanheng Li
Xinxian Fan
Jiamei Guo
Yifeng Lin
Yifan Gao
Lin Yang
author_facet Chunxiao Tang
Yuanheng Li
Xinxian Fan
Jiamei Guo
Yifeng Lin
Yifan Gao
Lin Yang
author_sort Chunxiao Tang
collection DOAJ
description Abstract Background Targeted Muscle Reinnervation (TMR) improves real-time control of EMG-based prostheses by connecting severed nerves to adjacent muscles, creating new EMG signals. However, TMR requires cutting original nerve connections, which can cause denervation atrophy and limit functional recovery. As an alternative, Targeted Nerve Function Replacement (TNFR) offers a fundamentally different approach by establishing a direct end-to-end anastomosis between an intact donor nerve and the original nerve of a target muscle, preserving existing neural pathways while providing supplementary neural input. This study evaluates TNFR efficacy in restoring denervated muscle function across different postoperative intervals in a rat model. Methods Thirty Sprague–Dawley rats (220–250 g) were divided into five equal groups (n = 6 per group): control (no transection), denervated (transection without repair), immediate TNFR after median nerve transection, 2-week delayed TNFR, and 4-week delayed TNFR. The median nerve was selected for reinnervation with the musculocutaneous nerve innervating the brachialis muscle serving as the anastomosis target. All assessments were conducted 4 weeks post-TNFR intervention, including intramuscular bipolar EMG recordings (1024 Hz sampling rate), behavioral assessment, muscle tension measurement, dorsal root ganglia (DRG) histology, and spinal cord motor neuron evaluation. Results Immediate TNFR significantly outperformed delayed interventions across all parameters. EMG amplitude and root mean square values were significantly higher in the immediate group (P < 0.05). Maximum contraction and tetanic contraction forces of biceps brachii showed superior recovery with immediate TNFR (P < 0.05). Histological examination revealed greater preservation of DRG sensory neurons following TNFR (P < 0.05). Immunofluorescence showed better preservation of synaptic protein expression in spinal cord motor neurons with immediate intervention. Immediate TNFR also prevented autophagic behavior seen in delayed intervention groups, suggesting improved neuropathic pain prevention. Conclusion Timing critically influences TNFR outcomes, with immediate intervention yielding optimal restoration of both motor and sensory functions. This study provides valuable insights for optimizing surgical strategies in peripheral nerve injury, with important implications for limb reconstruction, rehabilitation protocols, and prosthetic development. Graphical abstract
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spelling doaj-art-8fa5fd946ccc48da8176eb61ae789edd2025-08-20T04:01:26ZengBMCJournal of NeuroEngineering and Rehabilitation1743-00032025-07-0122111910.1186/s12984-025-01666-0Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat modelChunxiao Tang0Yuanheng Li1Xinxian Fan2Jiamei Guo3Yifeng Lin4Yifan Gao5Lin Yang6Zhuhai Campus of Zunyi Medical UniversityNeural Engineering Center, Shenzhen Institutes of Advanced Technology, Chinese Academy of SciencesSchool of Intelligent Medical Engineering, Shenzhen Technology UniversitySchool of Intelligent Medical Engineering, Shenzhen Technology UniversityZhuhai Campus of Zunyi Medical UniversityZhuhai Campus of Zunyi Medical UniversityZhuhai Campus of Zunyi Medical UniversityAbstract Background Targeted Muscle Reinnervation (TMR) improves real-time control of EMG-based prostheses by connecting severed nerves to adjacent muscles, creating new EMG signals. However, TMR requires cutting original nerve connections, which can cause denervation atrophy and limit functional recovery. As an alternative, Targeted Nerve Function Replacement (TNFR) offers a fundamentally different approach by establishing a direct end-to-end anastomosis between an intact donor nerve and the original nerve of a target muscle, preserving existing neural pathways while providing supplementary neural input. This study evaluates TNFR efficacy in restoring denervated muscle function across different postoperative intervals in a rat model. Methods Thirty Sprague–Dawley rats (220–250 g) were divided into five equal groups (n = 6 per group): control (no transection), denervated (transection without repair), immediate TNFR after median nerve transection, 2-week delayed TNFR, and 4-week delayed TNFR. The median nerve was selected for reinnervation with the musculocutaneous nerve innervating the brachialis muscle serving as the anastomosis target. All assessments were conducted 4 weeks post-TNFR intervention, including intramuscular bipolar EMG recordings (1024 Hz sampling rate), behavioral assessment, muscle tension measurement, dorsal root ganglia (DRG) histology, and spinal cord motor neuron evaluation. Results Immediate TNFR significantly outperformed delayed interventions across all parameters. EMG amplitude and root mean square values were significantly higher in the immediate group (P < 0.05). Maximum contraction and tetanic contraction forces of biceps brachii showed superior recovery with immediate TNFR (P < 0.05). Histological examination revealed greater preservation of DRG sensory neurons following TNFR (P < 0.05). Immunofluorescence showed better preservation of synaptic protein expression in spinal cord motor neurons with immediate intervention. Immediate TNFR also prevented autophagic behavior seen in delayed intervention groups, suggesting improved neuropathic pain prevention. Conclusion Timing critically influences TNFR outcomes, with immediate intervention yielding optimal restoration of both motor and sensory functions. This study provides valuable insights for optimizing surgical strategies in peripheral nerve injury, with important implications for limb reconstruction, rehabilitation protocols, and prosthetic development. Graphical abstracthttps://doi.org/10.1186/s12984-025-01666-0Targeted nerve function replacement (TNFR)Electromyography (EMG)Autophagic behaviorSpinal cordDorsal Root Ganglion (DRG)
spellingShingle Chunxiao Tang
Yuanheng Li
Xinxian Fan
Jiamei Guo
Yifeng Lin
Yifan Gao
Lin Yang
Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model
Journal of NeuroEngineering and Rehabilitation
Targeted nerve function replacement (TNFR)
Electromyography (EMG)
Autophagic behavior
Spinal cord
Dorsal Root Ganglion (DRG)
title Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model
title_full Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model
title_fullStr Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model
title_full_unstemmed Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model
title_short Improving nerve and muscle function: an exploration of targeted nerve function replacement following differential delay periods in a rat model
title_sort improving nerve and muscle function an exploration of targeted nerve function replacement following differential delay periods in a rat model
topic Targeted nerve function replacement (TNFR)
Electromyography (EMG)
Autophagic behavior
Spinal cord
Dorsal Root Ganglion (DRG)
url https://doi.org/10.1186/s12984-025-01666-0
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