What Is Functional Electrical Stimulation?

Electrical stimulation is the first method used in rehabilitation therapy. From the initial passive stimulation, it delays muscle atrophy, anti-inflammatory, and promotes the speed of recovery of the body due to muscle wasting in hemiplegia patients. Until now, there are various types of muscle stimulation and nerve stimulation. Various stimulation methods, which replace or correct the functions that have been lost in the limbs and organs, and also theoretically rebuild the nervous system function, are collectively referred to as functional electrical stimulation (FES).

Functional electrical stimulation (FES) belongs to the category of neuromuscular electrical stimulation (NES), which uses a certain intensity

1. Frequency: The frequency of FES is theoretically 1 ~ 100Hz

2. Pulse: often between 100 ~ 1000, more use 200 ~ 300.

3. Duty cycle: most are between 1: 1 and 1: 3.

4. Wave rise / wave fall: Wave rise refers to the time required to reach the maximum current. Wave drop refers to the time required to fall from the maximum current to power failure. The wave rise and wave drop usually take 1 ~ 2s.

5. When FES uses surface electrodes,

1. Replaces or corrects lost function of limbs and organs

2. Functional reconstruction. FES stimulates neuromuscles as well as afferents

Often applied to the following areas:

Paralysis of upper motor neurons

2. Respiratory dysfunction

3. Urinary dysfunction

4. Idiopathic scoliosis

5. Subluxation of the shoulder joint

The most prominent example of functional electrical stimulation is the cardiac pacemaker.

Functional stimulation includes therapeutic applications and applications to restore motor function. Therapeutic applications can further improve or prevent the further development of disability. In general, such applications are relatively short (the longest is only a few years); motor function recovery includes enhancing the control of upper limbs and the ability to transport lower limbs. When the nerve injury stabilizes, the function recovery method is started and maintained, which can benefit the user for life.

There are other applications.

1.Neural electronic stimulator for pain relief

Pain is an extremely complex clinical symptom, which is not directly proportional to the degree of damage to the body's tissues and organs. To a certain extent, pain is greatly affected by mental, emotional and psychological factors. Pain can cause patients to different levels of fear, panic, anxiety, sadness and other bad emotions, which can make patients feel mentally distressed and even affect their diet and living. With the acceleration of modern work, the pace of life and the arrival of an aging society, the impact of pain on human health is receiving more and more attention.

A Dutch company launched a small battery-powered ENS901 and ENSgll transcutaneous neuroelectronic stimulator, which uses electrodes placed near or distal to the pain area to send out electrical pulse waves to treat persistent pain. These electrical pulses can block painful stimuli transmitted to the spinal cord, and can initiate physiological control mechanisms that block the stimulus from reaching the chest. This treatment can reduce the use of drugs.

Lower limb walker

Paralysis of the lower extremities is a result of paralysis of motor neurons, which may be caused by cerebrovascular accidents, brain trauma, spinal cord injury, cerebral palsy, and sclerosis. The purpose of FES treatment is to help patients complete certain functional activities, such as walking, grasping, coordinating sports activities, and speeding up the recovery of arbitrary control. A number of scientific and technical personnel in Manchester, England, and researchers in 12 European countries have jointly developed an electronic device that enables people with lower limb paralysis to walk normally. This electronic device generates an electrical stimulus similar to the neural signals emitted by the brain, which can rejuvenate the patient's muscles and walk more freely. An electronic device that has been developed to assist the paralyzed person to walk is placed on the hip of the patient, which enables the patient to walk slowly for one kilometer. The new electronic device is placed in the patient's stomach, and it generates electrical stimulation similar to the corresponding neural signals generated by the brain itself. With this device in place, the patient can walk basically like a normal person without feeling tired. In addition, the electronic device enables the implanter to go up and down the stairs.

3.Upper limb assist

The movement of the upper limbs is much more complicated than that of the lower limbs. The 4-8 channel FES system is used to stimulate the hand and forearm muscles, allowing the patient to complete various grasping actions. Because the hand and forearm muscles are small, implanted electrodes are generally used to control the switch through the ipsilateral shoulder muscles or the contralateral upper limbs. A research team at Tohku University in Japan has developed a new method to recover lost transport functions. This method is accomplished by using electrodes implanted in the muscle to provide electrical stimulation. Without damage to the muscles, if only the signal transmission pathway is damaged, patients with stroke or spinal cord damage can also relax their motor senses. The new system designed by the research team, under computer control, stimulates the muscles by implanting electrodes in the muscles, which can move the arms of patients who have lost nerve function. This system plays the role of the damaged brain and muscle. American Neuromuscular Stimulation System Corporation has developed a neuromuscular electrical stimulation (NMES), a rehabilitation technology that uses low energy electrical stimulation to restore muscle control due to spinal cord injury. When the patient is operating, just press the button inside the device gently. Low energy current pulses act on muscles and enhance muscle function, which can still improve joint range of motion.

4.Respirator

The use of stimulation of the septum nerve to maintain breathing is probably the earliest attempt of clinical application of FES. The FES system used to control and regulate respiratory movement is a diaphragm pacemaker. A pair of implanted electrodes is embedded in the bilateral septal nerve (also can be placed on the bilateral septal nerve motor point with body surface electrodes) and connected to a signal receiver fixed on the chest wall. The controller sends out a radio pulse signal, which is converted into a low-frequency current by the receiver, which stimulates the septal nerve through the electrode, causing the diaphragm to contract. It is mainly used for respiratory muscle paralysis caused by cerebrovascular accident, brain trauma, and high spinal cord injury.

5.Urine incontinence controller

In fact, the spinal urinary center of this patient and the bladder detrusor and urethral sphincter under its control are still intact. One method of using FES to control urinary incontinence is to implant stimulating electrodes into the bladder detrusor muscle or its skeletal nerve root, or even the medial lateral column of the spinal cord. Another simple and practical method is to stimulate the urethral sphincter via the vagina or rectum.

6, visual aids

People who are completely blind due to eyeball lesions, in fact, the visual centers at all levels are still not affected. If FES is used to replace the afferent impulses of the retina, it should be possible for blind people to "see" the light again. There has been a lot of research in this area. After human experiments, it has been found that stimulating a certain part of the occipital cortex of the blind can make the blind "see" a light spot at a certain position in the visual field.

Hearing aids

The hearing nerve and auditory center are still intact due to cochlear (capillary chest) lesions. Therefore, some scholars have envisioned using micro-microphones with electronic computer processing to perform FES on the auditory nerve endings of the basement membrane of the cochlea to reconstruct hearing.

8, treatment of scoliosis

The disease is common in adolescents and the cause is unknown. The traditional treatment is to wear a spinal orthosis. However, due to the long wearing time (23 hours per day), the orthosis restricts the patient's movement and is uncomfortable, which affects the patient's image. The patient is often unwilling to wear it and the treatment is abandoned halfway. In the 1970s, a type of FES for the treatment of scoliosis came out. This kind of FES that can replace the orthosis is called "electrical.rthotic" (Bobeehk). First reported in 1979 that the system was successfully treated with implanted electrodes and radio frequency emission control. Because of the dangers and side effects of implanted electrodes, body surface electrodes have been used since the 1980s. By the month of 1989, more than 1,000 patients had been treated with the device, and 76% of patients with scoliosis had improved or maintained their condition.

It can also be applied to spinal fusion stimulation, percutaneous nerve stimulation midwifery, shoulder subluxation, and treatment of epilepsy ^[2] .