For complex regional pain syndrome, which modality is BEST to reach pain control?

• A. Cold spray
• B. NMES
• C. Transcutaneous electrical nerve stimulation (TENS)
• D. Iontophoresis

Answer: (C)

When managing pain in complex regional pain syndrome, a modality that modulates nociceptive input without causing tissue injury is most effective for pain control. Transcutaneous electrical nerve stimulation delivers electrical currents through the skin to activate large-diameter A-beta fibers, which helps close the gate at the spinal cord and reduce the transmission of pain signals. It can also engage endogenous opioid mechanisms with certain settings, providing meaningful analgesia while remaining noninvasive and safe. This makes TENS a practical, versatile option for CRPS pain, often used to achieve sustained pain relief and improve function.

Briefly, cold spray offers only short-lived numbness and, in CRPS, cooling can provoke exaggerated autonomic responses or worsen pain. NMES strengthens and re-educates muscles and can aid function, but its primary role is not pain control and it can provoke discomfort in sensitive patients. Iontophoresis delivers anti-inflammatory drugs through the skin and targets inflammation rather than directly modulating central pain processing, making it less effective for the neuropathic and centrally mediated aspects of CRPS pain.