A COTA has been working with a client recently diagnosed with complex regional pain syndrome of the upper extremity secondary to an improperly casted distal radius fracture. Which modality is BEST to reach the treatment goal of pain control for this client?

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

Answer: (C)

Pain control in complex regional pain syndrome hinges on providing safe, immediate, and adjustable analgesia that supports participation in rehabilitation. Transcutaneous electrical nerve stimulation achieves this by delivering small electrical pulses that activate large-diameter Aβ fibers, which helps gate or dampen pain signals at the spinal cord level. This creates short- and longer-acting relief without systemic meds, making it easier for the client to engage in range-of-motion activities, desensitization techniques, and functional tasks needed after a distal radius fracture.

In CRPS, where ongoing pain can drive protective guarding and limit movement, having a noninvasive method that can be used during therapy to reduce pain is particularly valuable. TENS is versatile in terms of frequency, intensity, and placement, so it can be tailored to the individual's sensitivity and tolerability, which is important given the possible allodynia and hyperalgesia associated with CRPS.

Other modalities offer different benefits but are not as directly aligned with rapid, controllable pain relief. Cold spray provides only brief, localized analgesia and can irritate sensitive skin; NMES focuses more on muscle activation and edema control rather than pain modulation and may provoke discomfort in a CRPS-affected limb; iontophoresis delivers medication through the skin and is less about immediate pain relief and more about anti-inflammatory effects over time, with skin reaction risks.