Second Harmonic Generation Imaging as a Virtual Biopsy for Upper Extremity Nerve Injuries: A Cadaver Study

Area of Science:

• Biomedical Engineering
• Microscopy
• Neuroscience

Background:

• Accurate nerve damage assessment is crucial for timely clinical decisions.
• Second Harmonic Generation (SHG) microscopy offers a method to visualize collagen, a key component of nerve tissue.
• The study aimed to evaluate SHG imaging's capability in human nerves.

Purpose of the Study:

• To determine if SHG imaging can differentiate collagenous substructures within human nerves.
• To assess SHG imaging's ability to detect structural damage in human nerves after mechanical injury.

Main Methods:

• Human upper extremities were divided into no-injury and load-to-failure (LTF) groups.
• Nerves (median, radial, ulnar) underwent mechanical stretch injury to transection.
• SHG microscopy was used to image nerves, followed by histological analysis.

Main Results:

• SHG imaging clearly identified and distinguished all collagenous substructures in uninjured nerves, matching histology.
• In LTF nerves, SHG imaging revealed epineurium rupture and exposed fascicles.
• Disorganized epineurial collagen with fragmented fibers was evident in injured nerves via SHG.

Conclusions:

• This study pioneers the use of SHG microscopy for visualizing human nervous tissue.
• SHG imaging provides detailed visualization of peripheral nerve collagen.
• SHG effectively detects nerve structural damage, including collagen disorganization and fascicle exposure.