In acute radial nerve palsy, can functional electrical stimulation (FES) be added to splinting and exercise to improve wrist extension and support flexor muscles, and what parameters should be used?

Functional Electrical Stimulation for Acute Radial Nerve Palsy with Wrist Drop

Add functional electrical stimulation (FES) to splinting and exercise therapy for acute radial nerve palsy—FES applied to wrist extensors for 30 minutes three times daily during active wrist extension attempts produces measurable gains in muscle force and motor control within the critical 6-month recovery window. 1, 2

FES Application Protocol

Surface electrode placement and timing:

• Position surface electrodes directly over the motor points of wrist and forearm extensor muscles 1, 3
• Apply stimulation for 30 minutes, three times daily during the patient's active attempts at wrist extension 1
• Initiate FES within the first 6 months post-injury to align with the critical window for motor recovery and maximize efficacy 1, 2

Integration with active rehabilitation:

• FES must be paired with intensive, task-specific wrist extension exercises—never use FES as a standalone treatment 1, 3
• Begin with supported wrist extension movements on a table surface, then progress to unsupported movements as strength improves 1
• The electrical stimulation provides proprioceptive feedback that promotes neural reorganization and motor learning, which passive modalities cannot deliver 3

Expected Outcomes

Motor recovery benefits:

• FES produces significant increases in wrist-extension muscle force based on meta-analysis of randomized controlled trials 1, 2
• Short-term application yields improved motor strength and motor control with measurable reduction in impairment severity 1, 2
• Recent evidence from a 2024 randomized study showed 89% treatment effectiveness when low-frequency pulse electrical stimulation was combined with exercise therapy, compared to 69% with exercise alone 4

Important limitation:

• While FES consistently improves muscle force, the evidence does not consistently demonstrate improvements in broader functional outcomes or activities of daily living 1

Splinting Strategy

Avoid static immobilization:

• Do not use static splinting or prolonged immobilization of the wrist—this promotes learned non-use, muscle deconditioning, compensatory movement patterns, increased pain, and poorer functional recovery 1, 3
• The American Stroke Association specifically advises against static splinting when FES is appropriate 1, 3

When splinting is necessary:

• If a removable resting splint is required for positioning when the patient lacks any active wrist movement, use it in combination with daily passive stretching and spasticity management 2
• Monitor closely for pain or skin breakdown and empower discontinuation if adverse effects arise 1
• The Royal College of Physicians advises against routine use of resting hand splints, while VA/DoD guidelines recommend them only as part of comprehensive management—this divergence reflects the controversial nature of isolated splinting 2

Critical Distinctions

FES versus TENS:

• FES actively contracts paralyzed muscles by delivering motor-level currents that depolarize peripheral motor nerves and produce functional movements 3
• TENS delivers only sensory-level currents for pain modulation and does not cause muscle contraction or provide the proprioceptive input required for motor recovery 3
• Do not confuse these modalities—FES has the strongest evidence for enhancing motor function in wrist drop 1, 3

Contraindication for CIMT:

• Constraint-induced movement therapy is not recommended for severe wrist drop because it requires minimum baseline function of ≈20° wrist extension and ≈10° finger extension, which these patients do not meet 1

Common Pitfalls

• Starting FES beyond the 6-month window reduces efficacy—the evidence base is strongest for early intervention 5, 1
• Using FES without concurrent active motor practice negates the neural reorganization benefits 1, 3
• Relying on static splinting instead of FES perpetuates weakness and delays functional recovery 1, 3