High-frequency TENS engages which pain-modulation concept?

• A. Gate control theory via mechanoreceptor stimulation
• B. Endorphin-mediated analgesia
• C. Central desensitization
• D. Nerve fiber transection

Answer: (A)

High-frequency TENS works mainly through the Gate Control Theory: it sends rapid electrical pulses that stimulate large-diameter mechanoreceptors (A-beta fibers). This non-nociceptive input activates inhibitory interneurons in the dorsal horn of the spinal cord, which reduces the transmission of pain signals from slower nociceptive fibers up to the brain. The result is quick, short-lasting analgesia as the spinal gate is effectively closed to some of the pain information.

Endorphin-mediated analgesia is associated with low-frequency, acupuncture-like TENS or longer-duration stimulation that engages endogenous opioid systems and descending pain pathways, producing different, often longer-lasting effects. Central desensitization is a broader CNS phenomenon and isn’t the primary mechanism by which high-frequency TENS gates pain at the spinal level. Nerve fiber transection is a surgical injury and not a mechanism used by TENS to modulate pain.