Electrode Placement for Wrist Drop from Deltoid Needle Injury
Place the FES electrodes on the forearm extensor muscles, NOT on the deltoid injury site. The deltoid is where the injury occurred, but wrist drop results from radial nerve dysfunction affecting the wrist and finger extensors located in the forearm—this is where therapeutic stimulation must be applied 1, 2.
Why the Forearm is the Correct Target
The fundamental principle of FES is to stimulate the paralyzed muscles directly to produce functional contraction and prevent disuse atrophy during neural recovery 1, 2. Your wrist extensors are located in the forearm, not the deltoid:
- The wrist and finger extensor muscles are the therapeutic target because these are the muscles that have lost function, causing your wrist drop 1, 3
- Stimulating the deltoid injury site would be both ineffective and potentially harmful—it would not activate the wrist extensors and could interfere with nerve healing at the injury location 2
- Electrode positioning on muscle motor points maximizes effectiveness by covering where nerve branches enter the muscle, which for wrist extensors is in the forearm 4
Optimal Electrode Placement Protocol
Proximal Forearm Placement (Recommended)
Position both electrodes proximally over the extensor surface of the forearm, just distal to the common extensor origin near the elbow 3. This approach:
- Produces stronger force generation with less discomfort compared to distal placement 3
- Maximizes recruitment of wrist and finger extensor motor units 4
- Allows targeting of synergistic muscles that produce functional wrist extension 5
Technical Specifications
- Use larger electrodes to stimulate greater muscle cross-sectional area and cover variable motor point locations, producing more force at a given discomfort level 4
- Apply a 100 μs interphase interval to biphasic pulses to enhance force production without increasing discomfort 3
- Stimulate for 30 minutes, 3 times daily during active attempts at wrist extension 2, 6
Critical Timing Consideration
You are at 20 days post-injury with no improvement—this signals that passive recovery is insufficient and active FES intervention is urgently needed 2, 6. Most motor recovery occurs within the first 6 months, making the next 3-4 months a critical window for intensive rehabilitation 2, 6. Rapid symptom relief typically occurs within 3-4 months with appropriate FES and structured rehabilitation 2, 6.
Common Pitfall to Avoid
Do not confuse the injury location (deltoid) with the treatment location (forearm extensors). The radial nerve was injured at the deltoid, but it controls muscles far distal to that point. FES must be applied where the paralyzed muscles are located to be effective 1, 2, 3.