“an unpleasant subjective sensory and emotional experience associated with tissue damage or potential tissue damage” (1). This definition clarifies that the essence of pain is an abnormal stimulus signal that tissue damage or potential tissue damage has occurred, alerting people that the damage and danger must be avoided or eliminated. For example, painful avoidance behaviors may result when a person is stabbed by a sharp object, and physicians may be alerted to the fact that a tissue injury is occurring in the body and may target treatment for the patient’s pain. The essence of this is the clarification that the tissue ultimately responsible for pain is the cerebral cortex, i.e., whether the injury or stimulus to the body becomes an unpleasant experience. Some self-masochists who take pleasure in bodily injury do not feel pain when they cut their bodies with a knife, and there are also somatization disorders in which abnormal foci of excitation in the cerebral cortex cause abnormal pain in a part of the body but the examination is perfectly normal. Therefore, the aim of treating pain is to restore the person’s subjective sensation to silence by means of actively seeking and targeting the location and cause of the tissue damage or abnormal stimulation in the body that triggers the pain and alleviating or eliminating its adverse effects on the brain. Of course not all tissue damage or stimulation will cause pain, such as when the injury is in hair, nails, bone and other tissues. In 1994, the IASP defined “pain resulting from primary injury or dysfunction or transient disturbance of the peripheral or central nervous system” as neuropathic pain (2). Many of the mechanisms involved in neuropathic pain are still unknown and therefore the most difficult to treat, and a lot of research funds have been invested in this area both nationally and internationally. In 2011, the IASP accepted the new definition of neuropathic pain proposed by the European Neuropathic Pain Interest Group in 2009, which limited the original general term “neurological injury” to “somatosensory neurological impairment” (3). The nerve endings of the somatosensory nervous system contain a large number of injury receptors. When lesions occur in the tissues around the nerve endings, such as inflammation, edema and scarring, the local nerve endings receptors will be stimulated or pressed and the local pain will be felt through nerve fiber conduction to the brain, such as myofascial injury, joint pain or visceral pain. Some parts of the cerebral cortex in the central sensory nervous system are the highest level cellular layer for pain sensation. In 2008, Treede proposed to classify pain into three categories, namely neuropathic pain, injury perception pain and psychogenic pain, and when more than two types of problems occur simultaneously, it is called mixed pain (4). This classification conforms to the anatomy and physiology of the sensory nervous system and has a good guideline for clinical treatment. It has gradually been accepted and adopted in the pain diagnosis and treatment criteria for the construction of cancer pain demonstration wards in China (). When the pain is prolonged or recurrent for more than one month, it is classified as chronic pain. 2004 IAS pointed out that chronic pain is a category of diseases, including neck, shoulder, back and leg pain and arthralgia in common injury perceptive pain, disc herniation, nerve entrapment syndrome, trigeminal neuralgia, herpes zoster neuralgia and diabetic neuralgia in neuropathic pain, and somatization disorder, depression or anxiety disorders, etc. In 2007, the Chinese Ministry of Health announced the establishment of the first level of clinical discipline “pain medicine”, and designated the scope of pain medicine as chronic pain (5). 쑗 In its extensive clinical practice, the Department of Pain Medicine has found that pain is defined as “unpleasant subjective sensory and emotional experiences in the brain caused by damage or abnormal stimulation of the sensory nervous system”. It can inherit and improve the definition of pain of IASP, the connotation of the definition of neuropathic pain and the essence of the three classifications of pain, which can explain or understand the pathophysiology and the whole process of pain occurrence, conduction and response more comprehensively. The sensory nervous system is distributed throughout the body, and pain medicine involves various clinical specialties. When a patient has pain, physicians are alerted to the fact that there is damage or potential damage to the body tissues, and they all try to solve the problems revealed by pain. The definition of pain as “an unpleasant subjective sensory and emotional experience of the brain caused by injury or abnormal stimulation of the sensory nervous system” is a good description of the scope of pain medicine. The sensory nervous system is the primary tissue in the body that conducts pain and has a well-defined anatomical form and physiological function. Pain physicians, like other clinical disciplines, devote their life and energy to disorders of the human sensory nervous system. In the process of specializing in finding and targeting the location and cause of sensory nervous system injuries, one trains and develops particularly sensitive and excellent diagnostic qualities and skills in pain medicine. We will become the backbone and main force in pain medicine, and we will all complement each other in many clinical disciplines to promote medical progress. The new definition can guide pain physicians to properly formulate the direction and strategy of treating pain, which is expected to breakthrough the efficacy of chronic pain more quickly. Targeting the cause of pain is the principle of clinical treatment and the preferred basis of treatment plan. Pain physicians have been working hard for many years and are now well able to target the cause of injury to sensory nerve endings for treatment with excellent results, such as myofascial pain, arthralgia, vertebral compression fracture pain, cervical and lumbar disc herniation pain, traumatic nerve entrapment pain, etc., which are the most common of neuropathic pain. Pain physicians are also able to give excellent pain relief when the pain patient is unwilling or unable to receive certain specialty treatments that can remove the cause of the pain, such as radiofrequency for trigeminal neuralgia, posterior branch release for small joint pain after vertebral slippage, etc. Pain physicians are aware that the level of pain in depressed patients is magnified and adds to the complexity of treatment, and will target and remove pain as a major trigger in antidepressant treatment. Analgesics are the basic weapon in the hands of the pain physician, and minimally invasive treatment is a good tool to reduce or discontinue medications. Whether the cause of chronic pain is clear or unclear, pain medicine needs to be obligated to help patients with analgesia, such as postherpetic neuralgia, diabetic neuralgia, postoperative pain syndrome, cancer pain, perineal pain, etc. Chronic pain patients no longer need to wander through multiple disciplines. The Department of Pain Medicine is dedicated to exploring the location and causes of sensory nerve damage, and on the basis of learning and accepting the techniques of various disciplines in treating pain, taking advantage of the puncture minimally invasive techniques, and constantly introducing new achievements in modern technology, it can make the treatment techniques of complex chronic pain diseases tend to be rational and scientific, and the efficacy of treating chronic pain will definitely be stronger than that of other specialties. Internationally, peers cast a concerned and even appreciative eye, and M.Y. DuBois, former president of the American Academy of Pain Medicine, suggested that pain medicine is not just about ensuring the competence of pain medicine specialists, but can significantly contribute to the effectiveness of pain treatment and enhance patient safety. He says our long-awaited vision has been realized in China (6). We must be self-improving and strive to improve our basic diagnostic skills, rather than being satisfied with the original mastery of a particular specialist’s technique, such as nerve blocks or small joint manipulation correction or open bone nailing. For chronic pain problems that are difficult to solve or require specialized techniques to effectively solve, pain physicians need to give special in-depth research and seek breakthroughs. The ultimate goal of analgesia is to protect the quiet state of brain sensation. We have dozens of analgesic drugs and non-invasive treatment and minimally invasive techniques for the cause of pain, and we can try our best to reduce the amount of analgesic drugs or even stop using them. The Pain Department is bold enough to take on the responsibility and to promise the community to the public that it will help relieve pain! In summary, the new definition of pain, “unpleasant subjective sensory and emotional experiences in the brain caused by damage or abnormal stimulation of the sensory nervous system”, inherits the IASP pain as The new definition of pain, “unpleasant subjective sensory and emotional experience of the brain associated with tissue damage”, includes the connotation of the original definition of “neuropathic pain is damage to the somatic sensory nervous system”, and explains the rationality of the three classifications of pain. It clarifies the clear scope of treatment in the pain department and guides physicians to find and treat the location and cause of injury or abnormal stimulation in the onset, conduction and perception of pain, which helps to break through chronic pain outcomes more quickly.