Pain after a spinal cord injury is a common complication. According to some foreign sources, more than 60% of paraplegics suffer from various types of pain caused by spinal cord injury. A British survey showed that 11% of paraplegics were incapacitated not by motor impairment due to paralysis, but by pain. Other data show that 23% of patients with low-level thoracic or lumbar spinal cord injuries suffer from severe pain, to the point of imagining that “I would rather not have other functions, such as sexual function, bowel control, etc., if I could just get rid of the pain”. However, compared to other complications of spinal cord injury, such as “spasticity”, pain is arguably more complex, because the mechanism of pain is not completely understood. If the mechanism of a disease is not clear, then the diagnosis, differential diagnosis, and treatment measures will be difficult. At present, there is no international consensus on the classification of pain, so here, I just give a brief description of the consensus part, and it should be pointed out that the pain and related mechanisms we are going to discuss today are based on animal models: Classification of spinal cord pain: According to the “International Society for the Study of Pain “According to the classification criteria of the International Society for the Study of Pain, pain after spinal cord injury is roughly divided into two major categories: first, injury-receptive pain, and second, neuropathic pain. Injury-receptive pain is divided into two subtypes: 1. Somatic pain: As the name suggests, it is related to the body and is also called “skeletal muscle pain”. In general, this type of pain is often described by patients as “numbness,” “pain,” “movement-related,” “relieved by rest,” and so on. ” and so on. At the same time, the treatment of this type of pain is effective with “opiates (morphine, fentanyl)” and “non-steroidal analgesics (aspirin)”. 2. Visceral pain: This kind of pain often occurs in the trunk area and is described by patients as “stomach cramps” and other pains that are “hard to say where the pain is”, and vascular headache also belongs to this type. Neuropathic pain is characterized by “sharp”, “radiating”, “electric shock”, “burning” pain. It may be accompanied by sensory hypersensitivity and pain hypersensitivity. The spinal cord is divided into three subtypes according to the location of the injury: 1, the upper type of injury: pain area, above the plane of injury. 2.Injury inner type: pain area, in the injury plane site. 3, the lower type of injury: pain area, below the plane of injury. Some scholars believe that psychological factors are a cause of pain, especially various chronic pain, however, there is no strong quantitative evidence and relevant animal experimental models about pain caused by psychological factors. The medical treatment of pain: 1, antidepressant medication: once considered the drug of choice for the treatment of pain after spinal cord injury, especially for “neuropathic pain”. For example: trazodone (triazolopyridine), currently undergoing “phase I trials”, but this drug, for certain types of pain, such as “diffuse burning pain”, “numbness pain “The effect is not very good. Regarding “diffuse burning pain”, some scholars believe that melitracen 150mg and flupenthixol 3mg mixed orally have some efficacy. However, such an observation needs to be further determined. 2, antiepileptic drugs: some scholars found that antiepileptic drugs for spinal cord injury pain effective, such as: valproate (valproate), carbamazepine (carbamazepine), and so on. However, the efficacy of these drugs needs to be further observed, because, according to current data, none of them can completely relieve pain, but only some degree of improvement. 3, sodium channel blockers: For example, lidocaine (lidocaine) is a drug that is not available in oral form, but only in injectable form. Many scholars have studied different injection methods, such as “intravenous injection” “subarachnoid injection” and so on. Injections of this drug can greatly relieve “spontaneous pain” and “tactilely induced pain” and “intractable pain”. The treatment effect is greater than 50% compared with the control patients who use “placebo”. 4, opioids: including “fentanyl”, “codeine”, “morphine” and so on. It is generally believed that the efficacy of this class of drugs for neuropathic pain is not as good as that of skeletal muscle pain. However, there are some observations that opiates, such as “fentanyl”, are more effective when administered by a specific route, such as intrathecal injection, in combination with other drugs (e.g., “colistin”). It has been shown that opiates, such as fentanyl, are equally effective in neuropathic pain when administered by a specific route, such as intrathecal injection, in combination with other drugs (e.g., colistin). It has also been found that intrathecal injections of a combination of morphine and codeine can provide significant pain relief, but that one drug alone is not effective. In addition to “intrathecal injection”, epidural injection has also been proven to be effective. 5, Clonidine (Colistin): This drug, once a “central hypotensive drug”, has been eliminated as an antihypertensive drug. In the treatment of spinal pain, the general use of injections, such as “intrathecal injection” “epidural injection” and so on, while this drug is often mixed with other drugs, such as and opiates mixed injection has been proven to relieve pain. 6, potassium channel blockers: for example: 4-aminopyridine (4-AP), this drug, oral efficacy, not as effective as the injection. Some researchers have found that 4-AP injections, can relieve pain while relieving lower limb spasms. However, the results of such studies, often in small sample groups of patients, and the results have not been subjected to rigorous quantitative analysis. 7. NMDA receptor stimulants: This class of drugs, mainly agonizing the central nerve “glutamate receptors”, thus acting on the central nociceptive mechanism, is represented by drugs such as ketamine (chlortalidone), which is a very common intravenous anesthetic drug for young children in clinical practice. It has been shown to be effective for “neuropathic pain”, but further in-depth studies are needed. 8, GABA agonist: representative drug: baclofen, many animal experiments show that this drug can inhibit “neuropathic pain”, can also inhibit “skeletal muscle type pain”. Generally speaking, the popular treatment method for this drug is “intrathecal injection”, which means that the drug is injected directly into the spinal cord cavity of the patient, which is beneficial not only for pain but also for relieving severe spasms after spinal cord injury. However, there are some scholars who believe that this treatment method has no significant effect on either spasticity or pain. There is no reliable evidence that this therapy is effective, but some patients with skeletal muscle pain and some patients with “intra-injury” neuropathic pain have reported that this therapy can relieve symptoms. 2, spinal cord stimulation therapy: this therapy, currently proved to be the most effective for “incomplete injury”, but the effectiveness of the treatment, will gradually decline with the extension of the treatment time. This therapy, for general patients with complete transection, the effect is not good, some patients with complete transection, below the plane of injury will appear severe pain, for this kind of pain from the loss of sensory area, spinal cord stimulation therapy has not been proven effective. 3, deep brain stimulation method: this treatment method, which was popular in 1970-1980, however, disappeared in 1990-2000. The key is that it is difficult to operate and pass the medical review of the National Food and Drug Administration (FDA), and there is always something more to lose than to gain for anyone to operate inside the brain to treat pain. Traditionally, this procedure is only used for patients for whom some other treatments have not worked and whose pain has seriously affected their quality of life, thus making the patient determined to undergo brain surgery to finally suppress the pain. 4. Lateral cordotomy, bilateral spinal cordotomy: The lateral cord of the spinal cord, which is the necessary pathway for nociceptive transmission impulses in the spinal cord stage, is theoretically believed to terminate pain by cutting off this anatomical structure. Some clinical evidence also shows that such therapy is effective due to the “severe pinch-like pain”, but not for other types of pain. Some surgeons also believe that if this procedure is to be performed, then a “bilateral lateral cordotomy” must be chosen, otherwise, if one side is cut, the structure on the other side is likely to show hyperactivity, which will aggravate the patient. However, the disadvantages of this treatment are obvious, as it is tantamount to adding another cut to the patient’s originally transected spinal cord. After surgery, it is likely that some of the patient’s remaining functions, such as bowel control and sexual function, will be further degraded or even completely lost. In addition, this treatment method is not theoretically infallible, and many patients with complete transection will feel severe pain from below the level of the injury. How do you cut in such a case? 5.Posterior rhizotomy: The heel of the spinal cord is the first station of sensory afferents. People’s pain and temperature sensations are afferent from the heel, and then rise 1-2 spinal cord stages on the same side to the opposite side, forming the “lateral cord” that we mentioned above, and then further up to the brain. The first academic report on this procedure was published in 1976. Since then, many surgeons have tried this procedure on patients with spinal cord injuries. Comparative studies have shown that this procedure is effective for “pain at the plane of injury”, “pain below the plane of injury”, and pain on the side of the body. The surgical procedure can be performed by electrodesiccation, superficial laminar coagulation of the posterior horn, or microsurgical excision. The extent of excision is generally two stages up from the site of injury. Currently, the more advanced surgical procedure is the “spontaneous intramedullary recording device guided dorsal rhizotomy”, a new technique that has resulted in 50%-100% relief in 21 of 25 subjects.