Challenges Faced by Patients with Upper Limb Dysfunction
The mano is an essential organ for daily activities and serves as a key tool for humans to explore the external world and interact with the environment. Compared to other body parts, the mano and upper limb possess greater complexity and importance in motor functions. Therefore, upper limb motor función rehabilitación is a core focus in post-ictus rehabilitación, yet it also represents a major challenge. Patients with upper limb dysfunction caused by conditions such as ictus, spinal cord lesión, or mano trauma often experience a slow recuperación process due to the complexity of mano and upper limb movements. This prolonged rehabilitación journey poses a significant psychological challenge, potentially affecting patients' sense of self-fulfilment, and may lead to anxiety, depression, and other emotional issues. These negative emotions can, in turn, further diminish rehabilitación motivation and impact the overall quality of life.

Functional Electrical Stimulation (FES) is a rehabilitación technique that uses low-frequency pulsed electrical currents to stimulate one or more groups of muscles through preset programs, inducing músculo contractions or simulating normal voluntary movements. The goal of FES is to mejorar or restore the functions of muscles and músculo groups affected by neurological damage, thereby compensating for or correcting the loss of motor función in limbs and organs. In recent years, the application of FES has expanded significantly, especially for patients with limb dysfunction caused by ictus or spinal cord lesión. Through repeated electrical stimulation, FES can not only activate motor neurons but also promote neuroplasticity in the central nervous system, helping patients gradually regain voluntary motor abilities.

3. Common Electrode Placements for FES in Limb Training
(1) Shoulder Subluxation
Patients with central nervous system injuries or high-level spinal cord injuries often experience shoulder subluxation. Strengthening the supraspinatus and the posterior part of the deltoid músculo can help prevent and mejorar shoulder subluxation.
Stimulation electrode: Placed on the posterior one-third of the deltoid músculo;
Auxiliary electrode: Placed on the supraspinatus músculo.

(2) Triceps Músculo Weakness
For patients with central nervous system disorders, using NMES to strengthen the triceps brachii can enhance elbow extension control and relieve spasticity of the biceps brachii.
Stimulation electrode: Placed below the posterior part of the deltoid músculo;
Auxiliary electrode: Placed above the olecranon (be careful to avoid stimulating the brachioradialis to prevent unwanted elbow flexion).

(3) Wrist and Finger Extensor Músculo Weakness
Due to the small size of forearm muscles, smaller electrode pads are generally recommended for stimulating the wrist and finger extensor muscles.
For wrist extensors:
Stimulation electrode: Placed below the lateral epicondyle of the humerus;
Auxiliary electrode: Placed proximally near the wrist joint.
For finger extensors:
Stimulation electrode: Placed more distally in the center of the forearm;
Auxiliary electrode: Placed proximally near the wrist joint.
