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Second Harmonic Generation Imaging Reveals Extent of Damage in Acute Nerve Stretch Injuries in Rats
Christoph A Schroen1, Philip Nasser2, Arne H Boecker3
1Department of Hand-, Plastic and Reconstructive Surgery, BG Trauma Center Ludwigshafen, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany; Leni & Peter W. May Department of Orthopaedic Surgery, Icahn School of Medicine at Mount Sinai, New York, New York.
The Journal of Surgical Research
|May 15, 2026
Summary
Second-harmonic generation (SHG) imaging can differentiate nerve injury severity intraoperatively. This label-free technique visualizes collagen damage, aiding surgical decisions for acute nerve trauma.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Surgical Imaging
Background:
- In-continuity nerve injuries present unpredictable outcomes and poor long-term recovery.
- Second-harmonic generation (SHG) imaging offers a label-free method for intraoperative visualization of collagen fibers.
- Distinguishing between epineuroclasis and endoneuroclasis is crucial for managing acute nerve trauma.
Purpose of the Study:
- To investigate the utility of intraoperative SHG imaging in differentiating two degrees of acute nerve stretch injury: epineuroclasis and endoneuroclasis.
- To assess SHG imaging's ability to reveal structural damage and injury severity in a rat model.
- To evaluate SHG imaging as a potential intraoperative diagnostic tool for guiding surgical management of nerve trauma.
Main Methods:
- Forty-five Sprague-Dawley rats underwent median nerve stretch injury, with the contralateral nerve serving as a sham control.
- Nerve function was assessed using electrical stimulation thresholds before and after injury.
- Intraoperative SHG imaging was employed to visualize the nerve's collagenous framework.
Main Results:
- SHG imaging identified three distinct zones in injured nerves: exposed endoneurial core, epineurial disruption, and disorganized collagen.
- Endoneuroclasis exhibited more severe endoneurial damage compared to epineuroclasis.
- Electrical stimulation thresholds significantly increased post-injury, with endoneuroclasis showing a greater reduction in conductivity (200 nC difference, P<0.001).
Conclusions:
- Intraoperative SHG imaging effectively visualizes epineurium rupture and endoneurial collagen disorganization.
- The technique allows for visual assessment of structural damage extent and injury severity.
- SHG imaging shows promise as an intraoperative tool to guide surgical decision-making in acute nerve trauma management.
