• Kenneth B Chapman, Tariq A Yousef, Allison Foster, D Stanton-HicksMichaelMDepartment of Pain Management, Cleveland Clinic, Cleveland, OH, USA., and Noud van Helmond.
• Spine & Pain Institute of New York, New York City, NY, USA.
• Neuromodulation. 2021 Jun 1; 24 (4): 738-745.

BackgroundDorsal root ganglion stimulation (DRG-S) involves the electrical modulation of the somata of afferent neural fibers to treat chronic pain. DRG-S has demonstrated clinical efficacy at frequencies lower than typically used with spinal cord stimulation (SCS). In a clinical study, we found that the frequency of DRG-S can be tapered to a frequency as low as 4 Hz with no loss of efficacy. This review discusses possible mechanisms of action underlying effective pain relief with very low-frequency DRG-S.Materials And MethodsWe performed a literature review to explore the role of frequency in neural transmission and the corresponding relevance of frequency settings with neuromodulation.FindingsSensory neural transmission is a frequency-modulated system, with signal frequency determining which mechanisms are activated in the dorsal horn. In the dorsal horn, low-frequency signaling (<20 Hz) activates inhibitory processes while higher frequencies (>25 Hz) are excitatory. Physiologically, low-threshold mechanoreceptors (LTMRs) fibers transmit or modulate innocuous mechanical touch at frequencies as low as 0.5-5 Hz, while nociceptive fibers transmit pain at high frequencies. We postulate that very low-frequency DRG-S, at least partially, harnesses LTMRs and the native endogenous opioid system. Utilizing lower stimulation frequency decreases the total energy delivery used for DRG-S, extends battery life, and facilitates the development of devices with smaller generators.© 2020 International Neuromodulation Society.

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