What Is Transcutaneous Electrical Nerve Stimulation?

The nervous system functions through electrical signals. Based on this basis, electrical signals are used to stimulate different nerves or brain regions to achieve the effect of pain. It can be called electrical stimulation analgesia. It is mainly used for chronic pain and postoperative analgesia.

The nervous system functions through electrical signals. Based on this basis, electrical signals are used to stimulate different nerves or brain regions to achieve the effect of pain. It can be called electrical stimulation analgesia. It is mainly used for chronic pain and postoperative analgesia.

According to the location of stimulation, current electrical analgesia can be divided into percutaneous electrical nerve stimulation (TENS), electrical spinal cord stimulation and central stimulation.

Percutaneous electrical nerve stimulation ( TENS )

Mechanism

(1) Gate control theory [1,2]

The theory suggests that the activation of thick fibers (A fibers) that conduct peripheral tactile and pressure sensations can inhibit the transmission of excitement signals from fine fibers (C fibers) that conduct pain and temperature. Both types of fibers can transmit excitatory stimuli to secondary neurons (T cells) in the posterior horn of the spinal cord, and also synapse with glial cells (SG cells) around T cells, and SG cells Peripheral pain stimuli that inhibit incoming T cells are transmitted to the high center. Stimulation from coarse fibers can enhance the inhibition of SG cells, while stimulation from fine fibers weakens the inhibitory effect of SG cells, indicating that SG cells play a gate-like control role in pain stimulation into T cells: coarse When the fiber afferent is strengthened, the gate is closed, and the nociceptive stimulus of entering T cells becomes weaker; when the fine fiber afferent is enhanced, the gate is opened, and the pain stimulus is continuously uploaded to the center, which produces persistent pain. TENS technology is a treatment method based on the theory of gate control. High-frequency, low-intensity electrical stimulation (greater than 50 Hz, generally 80 to 110 Hz; wave width 0.1 to 0.2 ms) is mainly used to excite A fibers, and then excite SG cells, and inhibit fine fiber pain stimulation uploading.

(II) Endogenous opioid peptide release theory [2,3]

Academician Han Jisheng and research team proposed for the first time that low-frequency (2 Hz) electroacupuncture (EA) stimulation can cause brain to release endorphin and spinal cord to release enkephalin, and high-frequency (100 Hz) electroacupuncture can promote spinal cord to release dynorphin. Peptides; at the same time, 2/100 Hz (sparse wave) can stimulate the simultaneous release of the above three opioid peptides, producing a synergistic analgesic effect.

Clinical application

1. It can be used for analgesia during surgery to reduce the amount of narcotic drugs; it can reduce the dosage of analgesics and reduce the incidence of nausea and dizziness.

2. Chronic pain, such as diabetic peripheral neuralgia, chronic low back pain

3. Cancerous pain. Although opioids and adjuvant analgesics can effectively alleviate cancer pain in most patients, side effects related to drug treatment are difficult to overcome, which is one of the main reasons affecting the clinical analgesic effect. Therefore, there is an urgent need for effective non-drug means to improve the analgesic effect and reduce side effects. From this perspective, TENS has broad clinical research value and application prospects in this field.

Spinal cord stimulation

Spinal cord stimulation (scs) refers to placing the electrodes of the spinal cord stimulator on the back of the epidural space of the spinal canal and stimulating the conduction beam of the posterior spinal column and sensory neurons in the posterior horn by electric current to treat pain or Other diseases.

Mechanism

The epidural space SCS can promote the release of endogenous analgesics to varying degrees. When low-frequency electrical stimulation, the enkephalin and endorphin in the cerebrospinal fluid can be increased; when high-frequency stimulation is made, the dynorphin content in the spinal cord increases and the release increases, thereby exerting the endogenous analgesic effect. Some scholars believe that the effect of SCS is in line with the sluice theory: there is an entrance to the spinal cord to control pain signals into the brain, and low current stimulates the spinal cord to activate pain and inhibit nerve fibers, thus closing the transmission of pain information, thereby alleviating and blocking pain feeling.

Indications:

More than a hundred articles have described the treatment effect of this method and confirmed its treatment effect. The first is the treatment of spinal injuries and pain syndromes after spinal surgery, which accounts for about 70% of all cases, and the second is also very effective in treating peripheral limb ischemic pain and post-amputation pain.

Central stimulation analgesia ( DBS ) [4]

So far, the treatment of chronic pain by central stimulation is still in a small-scale experimental stage. On the one hand, it is due to the unstable effect of central stimulation on pain, and on the other hand, the mechanism of analgesia is not clear. Existing central stimulation analgesia methods include deep brain stimulation, motor cortical stimulation, etc., that is, electrodes are implanted into the deep nucleus or motor cortex of the central nervous system to relieve pain.

Clinical application of central electrical stimulation for analgesia can relieve or even eliminate chronic pain, improve the quality of life of patients, and also lay the foundation for the treatment of other neurological diseases. DBS has been used to treat epilepsy or other neuromotor diseases (such as Parkinson's disease). Because chronic pain also involves the patient's emotional problems, DBS alleviates chronic pain is beneficial to improve the patient's mental health. For basic research, studying central electrical stimulation analgesia can explore the central mechanism of chronic pain, find the best neural target for chronic pain, and improve the success rate of analgesia; by studying the mechanism of central electrical stimulation analgesia, It is possible to find out the functional connections between multiple neural nucleus groups or structures, and to increase the understanding of the formation and treatment mechanism of chronic pain.

[1] Melzack R, Wall PD. Pain mechanisms: a new theory. Survey of Anesthesiology, 1967, 11:89 ~ 90.

[2] Li Xiaomei. Progress of clinical analgesia with percutaneous electrical acupoint stimulation, Chinese Journal of Pain Medicine, 2014, 20 (11).

[3] Fei H, Xie GX, Han JS. Low and high frequency electroacupuncture stimulation release met-enkephalin and dynorphin A in rat spinal cord. Chin Sci Bull, 1987,

32: 1496 ~ 1501.

[4] Zhou Jiashu, Wang Jinzhang, Luo Fei. Review of central stimulation analgesia and its mechanism. Chinese Journal of Pain Medicine 2007, 13, (4).