The Preliminary Research Of Identifying Motor And Sensory Fiber By Near-infrared Spectroscopy

Objective The aim of this study was to determine the feasibility of usingnear-infrared spectroscopy (NIRS) to identify motor and sensory fascicles,providing a rapid method for identifying motor and sensory fiber.Methods 12 adult Beagle dogs were anesthetized generally and werekilled. From all 12 of the dogs, canalis vertebralis were opened, and bothanterior and posterior roots were harvested from L₁-S₂. 126 anteriorroots and 126 posterior roots were collected, cauda equines, 20 facialnerves and 20 cutaneous nerves of neck were harvested from the Beagledogs. These nerves were kept in the liquid nitrogen. When to use, thenerves deforest under the room temperature, and then were kept in moistcase to prevent the specimen drying and dehydrating. NIR spectra weremeasured using a MPA Fourier transform near infrared (FT-NIR)spectrometer. Each sample was put directly onto the top of the optic fiberprobe or in the external transmission of the FT-NIR. Each spectrum represented the average of 64 scans at a resolution of 8cm^-1. Duplicates ofeach sample were scanned three times. The average spectrum of eachsample was used for further analysis. Second derivative spectra were usedto reduce baseline variations observed in original diffuse reflectancespectra as well as to enhance spectral features. To develop a calibrationmodel, soft independent modeling of class analogy (SIMCA) was used toclassify each class according to its analogy to the training samples.Cluster analysis of the pattern recognition was adopted. FuminoriEnzyme-Staining method was compared with NIRS.Results The results showed that the anterior and posterior roots havequite similar first-derivative and second-derivative spectra of thenear-infrared spectroscopy and unable to be directly distinguished. Therewere no clear differences from the spectra between the anterior andposterior roots of samples. The facial nerves and the cutaneous nerves ofneck were also. Different spinal nerve roots of the Beagles could bedirectly distinguished by clustering analysis or SIMCA. The facial nervesand the cutaneous nerves of neck were could be directly distinguished byclustering analysis. Original spectral data were transformed to secondderivate spectral data. SIMCA was employed to identify the anterior andposterior roots based upon differences in their spectral features. SIMCAModels correctly classified 79.2-100.0% for the anterior and posteriorroots of spinal nerves, and mean 83.7%. Clustering analysis correctly identified 87.5% for the anterior and posterior roots of the cauda equines,and 90.0% for the facial nerves and the cutaneous nerves of neck, and84.6% for the anterior and posterior roots of spinal nerves. The exact rateof 2 hour staining result of Fuminori Enzyme-Staining Techniques was100%, NIRS Techniques only needs 2 minutes to identify the property ofnerve fiber and have more superiority in clinical application.Conclusion This study demonstrated that NIR spectroscopy incombination with multivariate data analysis methods(SIMCA)/clusteringanalysis could be used to classify the sensory and motor nerves. Thisresult suggests that NIR spectroscopy may provide a rapid, correct,non-destructive, low-cost means to quickly differentiate motor andsensory fascicles in mixed nerves.