Accurate intraoperative assessment of peripheral nerve injury is critical to optimizing surgical decisions and improving patient outcomes, yet current diagnostic tools provide limited specificity to differentiate among uninjured, injured, and regenerating nerve tissue. This paper investigates the feasibility of multispectral photoacoustic imaging to distinguish the absence, presence, and/or severity of nerve injury using \textit{ex vivo} nerve samples from two swine. Ulnar and median nerves were subjected to one of three conditions: (1) uninjured, (2) transected (injured), or (3) immediate repair following transection (regenerating). These conditions were confirmed through histopathologic analysis using toluidine blue staining. Photoacoustic images were acquired over a 1200-2000 nm wavelength range. Representative photoacoustic spectra revealed distinct spectral signatures among the three nerve states, particularly in the 1240-1300 nm and 1350-1700 nm ranges. Injured and regenerating nerves exhibited greater absorption amplitudes than uninjured nerves across the noted wavelength ranges, indicating changes in tissue composition during nerve injury and repair. These results demonstrate the feasibility of multispectral photoacoustic imaging as a real-time method to identify nerve injury and regeneration, enabling future intraoperative assessment and surgical guidance.
