| dc.description.abstract | In this study, parameters for the clinical application of optical neural stimulation were developed. Two pulsed diode lasers, with wavelengths centered at 1875 nm and 1450 nm respectively, were used to elicit compound motor action potentials (CMAPs) in Sprague-Dawley rats via irradiation of the sciatic nerve. Comparisons were made between flat-top and Gaussian beam profiles, laser spot size, and damage margins. An unpaired parametric analysis revealed that 1450 nm light required a statistically significant lower radiant exposure than 1875 nm to evoke CMAPs. These findings revealed a 5:1 safety ratio of stimulation via 1450 nm light. There was no statistically significant difference in the radiant exposure needed to evoke action potentials between flat-top and Gaussian beam profiles. Spot size showed a minor correlation with stimulation thresholds at 1875 nm light, but not 1450 nm light. However no trends were observed when comparing the two wavelengths. These results were used to compare INS with electrical stimulation methods for nerve monitoring in healthy and damaged nerves. This comparison revealed that optically evoked signals did not propagate beyond the site of damage in injured nerves, whereas electrically evoked signals did. We thus argue that the use of 1450 nm light will lead to safer and more repeatable stimulations of neurological sites of interest, enabling use as an adjunct to electrical methods in nerve monitoring. | |
