Nerve-Stimulation-Induced Near-Infrared Optical Signals Distinguish Diabetic Muscles from Healthy Muscles (P07.199)

Abstract

Objective: To test the hypothesis that signals obtained using Near-Infrared Spectroscopy (NIRS) following nerve stimulation are sensitive to changes in muscle function that accompany diabetes. Background The tools available for monitoring changes in muscle and nerve function (EMG) are sensitive to the electrical health of nerve and muscle. We have been studying the biological origin of an optical signal that occurs immediately following brief (0.1 ms) nerve stimulation. We have previously shown that the signal, which lasts approximately 160 ms, is eliminated by a curariform neuromuscular block and that its time course carries information about the speed of muscle contraction. These facts suggest that the signal reports on the kinematic properties of muscle and could be useful as a biomarker for diabetic myopathy. Design/Methods: 70 subjects participated, including healthy subjects and subjects diagnosed with diabetes. Three experimental protocols were used: (1) While stimulating the median nerve in the wrist, we simultaneously measured the force generated by the thumb and optical signals from abductor pollicis brevis (APB). (2) While stimulating the common peroneal nerve, we simultaneously measured the force generated by dorsiflexion of the foot and optical signals obtained tibialis anterior (TA). (3) While stimulating the tibial nerve, we measured the force generated by plantarflexion of the foot and optical signals from gasctrocnemius (Gast.). Results: In all subjects, NIRS signals had multiple peaks and were more complex than force signals. NIRS signals obtained from TA and Gast. were broader than those obtained from APB. Moreover, NIRS signals from APB had smaller amplitudes in subjects with diabetes compared to control subjects. Conclusions: NIRS has been widely used to investigate hemodynamic and metabolic events in both CNS tissue and muscle. Our results suggest that information about muscle structure and kinematics may also be available using NIRS. Supported by: NIH Grants NIA T32-001, T32-AG00277, and by CIMIT/U.S. Army Medical Acquisition Activity (USAMRAA) funding under cooperative agreement no. W81XWH-07-2-0011. Disclosure: Dr. Erb has nothing to disclose. Dr. Macomber has nothing to disclose. Dr. Bergethon has nothing to disclose.