• Fei Yang, Tong Zhang, Vinod Tiwari, Bin Shu, Chen Zhang, Yun Wang, Louis P Vera-Portocarrero, Srinivasa N Raja, and Yun Guan.
• Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
• Neuromodulation. 2015 Oct 1; 18 (7): 592-7; discussion 598.

ObjectivesElectrical stimulation at the dorsal column (DC) and dorsal root (DR) may inhibit spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. The objective of this study was to determine if applying electrical conditioning stimulation (CS) at both sites provides additive or synergistic benefits.Materials And MethodsBy conducting in vivo extracellular recordings of WDR neurons in rats that had undergone L5 spinal nerve ligation, we tested whether combining 50 Hz CS at the two sites in either a concurrent (2.5 min) or alternate (5 min) pattern inhibits WDR neuronal activity better than CS at DC alone (5 min). The intensities of CS were determined by recording antidromic compound action potentials to graded stimulation at the DC and DR. We measured the current thresholds that resulted in the first detectable Aα/β waveform (Ab0) and the peak Aα/β waveform (Ab1) to select CS intensity at each site. The same number of electrical pulses and amount of current were delivered in different patterns to allow comparison.ResultsAt a moderate intensity of 50% (Ab0 + Ab1), different patterns of CS all attenuated the C-component of WDR neurons in response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 msec) and inhibited windup in response to repetitive noxious stimuli (0.5 Hz). However, the inhibitory effects did not differ significantly between different patterns. At the lower intensity (Ab0), no CS inhibited WDR neurons.ConclusionsThese findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons.© 2015 International Neuromodulation Society.

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