Blocking the cerebral nerve, spinal nerve and its ganglia or sympathetic ganglia with local anesthetics to relieve pain, improve blood circulation, and treat painful diseases is called nerve block therapy. Although the operation method of nerve block therapy is basically the same as that of nerve block, the drugs used and their concentrations may be different due to the different purposes, and the positions adopted during the execution of certain operations are also different. Nerve block includes chemical block and physical block. Chemical nerve block therapy mainly uses local anesthetics to block the conduction function and can be used for analgesia during surgery, but more often for pain management. Nerve blocks using conventional local anesthetics are generally reversible. Nerve blocks with high concentrations of local anesthetics or nerve-disrupting drugs for certain therapeutic purposes can block conduction function for longer periods of time or permanently ( irreversible). The clinical use of physical methods such as heating, pressure or cooling to block nerve conduction is called physical nerve block. In clinical practice, the purpose of nerve block mainly includes: 1.Therapeutic nerve block: the nerve block can eliminate pain, improve blood flow, and achieve the purpose of treatment. 2.Diagnostic nerve block: After blocking the intrinsic nerve or segmental spinal nerve, diagnosis is made according to the disappearance of pain. 3.Nerve block used to judge the prognosis. 2.The mechanism of action of nerve block therapy 1.Block the nerve conduction pathway of pain. 2. Blocking the vicious circle of pain: clinical observation shows that the analgesic time produced by the application of local anesthetic nerve block significantly exceeds the anesthetic action time of the local anesthetic itself. It is generally believed that this is due to the fact that nerve block therapy cuts off the vicious circle of “pain – muscle tension or small vessel smooth muscle spasm and pain intensification”. 3.Improve blood circulation: sympathetic nerve block can improve the blood flow in its innervation area, thus effectively improving the pain caused by poor peripheral blood circulation. 4.Anti-inflammatory effect: Research has confirmed that nerve block therapy, especially sympathetic nerve block therapy, has anti-inflammatory effect, and thus produces good analgesic effect. Characteristics of nerve block therapy Nerve block therapy has the following characteristics: reliable analgesic effect; important to the diagnosis of the disease; selective treatment scope and duration; no special equipment, devices; small adverse reactions; efficacy and operating skills are closely related. The indications and contraindications of nerve block therapy are very broad, it is not only limited to the treatment of various acute and chronic pain, but also can be used to treat many non-painful symptoms and diseases. It is not only limited to the treatment of acute and chronic pain, but also can be used to treat many non-painful symptoms and diseases. Patients with infection, inflammation or serious systemic infection at the block site, bleeding tendency or history of allergy to local anesthetics are contraindicated.