Identification of Motor and Sensory Fascicles in Peripheral Nerve Trunk Using Immunohistochemistry and Micro-Raman Spectroscopy

Objective: To explore a time-efficient method of identifying motor and sensory fascicles in peripheral nerve trunk. Methods: Thirty Wistar rats were selected to obtain whole spine. The spinal dorsal roots and ventral roots, and sciatic nerve were harvested as sensor, motor, and mixed samples, annexin V and agrin specificities were observed with Western blot and immunohistochemistry. A total of 32 New Zealand rabbits were selected and killed. The roots of spinal nerves were exposed under an operating microscope, and the ventral and dorsal roots, ∼3 mm to 5 mm, were dissociated, and frozen as transverse sections of 30-μm thickness. The sections were examined by micro-Raman spectroscopy. Results: The annexin V and agrin were special substances of sensory and motor nerves, respectively, and can act as specific antigens for identifying different nerve fascicles. Sections of the same type of nerve fascicles showed reproducibility with similar spectral features. Significant differences in the spectral properties, such as the intensity and breadth of the peak, were found between motor and sensory fascicles in the frequency regions of 1,088 cm−1, 1,276 cm−1, 1,439 cm−1, 1,579 cm−1, and 1,659 cm−1. With the peak intensity ratio of 1.06 (I1276/I1439) as a standard, we could identify motor fascicles with a sensitivity of 88%, specificity of 94%, positive predictive value of 93%, and negative predictive value of 88%. In the range of 2,700 cm−1 to 3,500 cm−1, the half-peak width of the motor fascicles was narrow and sharp, whereas that of the sensory fascicles was relatively wider. A total of 91% of the peak features were in accordance with the identification standard. Conclusion: Motor and sensory fascicles exhibit different characteristics in Raman spectra, which are constant and reliable. Therefore, it is more effective than immunohistochemistry method in identifying different nerve fascicles according to the specific spectrum, and it possesses feasibility for clinical application.