I. Course of disease and pathological changes The course of PHN is generally about 1-3 years, if there is no effective method of pain control, the general history of the disease can be up to 3 years or more, and a few patients may have a pain cycle of up to 10 years, and patients who suffer from severe pain for a long time suffer, not only depressed, survival and quality of life is seriously reduced. Statistically the likelihood of pain lasting >1 year is 4-10% in the 10-49 year old group and 18-48% in the 50-79 year old group, with individual patients lasting up to 10 years or more. Although the pain of PHN is associated with acute herpes zoster, there are still different views on whether it is simply a temporal continuation of acute herpes zoster or another type of pain of a different nature, and most scholars tend to consider them as two different types of pain. It has been suggested that patients with PHN have atrophy and sensory ganglion lesions on the infected side of the dorsal horn, whereas patients with acute herpes zoster have no such changes. In addition, many data suggest that pain in PHN is due to alterations in the number and proportion of peripheral nerve fibers and peripheral nerve sensitization, in addition to central mechanisms (abnormal integration and central sensitization and alterations in downstream inhibitory mechanisms, etc.). The incidence of PHN is directly proportional to age. The proportion is 15% for head and face, 12% for neck and collar, 55% for chest and back, 14% for lumbar abdomen, 3% for sacrococcygeal region, and about 1% for generalized. Clinical manifestations When the ophthalmic branch of trigeminal nerve (fifth cerebral nerve) is involved, it can involve cornea and affect vision; invasion of facial nerve (seventh cerebral nerve) and auditory nerve (eighth cerebral nerve) can lead to facial palsy and auditory symptoms; in the sacral region (S3 neuron) can lead to neurogenic bladder, difficulty in urination or drowning, etc., but it can recover. Some patients are afraid to wear clothes in order to reduce clothing irritation, and some patients also hold up their clothes from time to time in order to avoid painful attacks caused by clothing irritation. This kind of pain hypersensitivity reaction, some also manifested as spontaneous pain, no thing touched the affected part also often occur pain. Some patients suffer a lot of mental and psychological damage because of the pain, even if they can’t eat and sleep at night. Other patients are emotionally overstressed due to long-term pain, and some are depressed and desperate. Fourth, treatment methods At present, Western medicine at home and abroad believes that it is extremely difficult to completely restore the pain and sensory abnormalities of postherpetic neuralgia patients to normal. To date, a large number of various therapies have been tried for postherpetic neuralgia, but a decisive and long-term cure has not been found. The treatment of refractory postherpetic neuralgia is mainly aimed at relieving pain, improving sleep, and improving quality of life, while less severe postherpetic neuralgia is aimed at promoting complete recovery. Our department has accumulated rich experience in the treatment of herpes zoster and post-herpetic neuralgia, and the treatment effect has been affirmed by patients and their families. Commonly used methods are as follows: 1. Oral medication Currently, oral administration is still the preferred method of treatment for postherpetic neuralgia PHN. Drug therapy mainly includes: non-steroidal anti-inflammatory analgesics, opioids (extended release), antidepressants, antiepileptics, sedatives, etc. 2. nerve block In the early stage of postherpetic neuralgia, nerve block has some effect. Stellate nerve block, epidural block, paravertebral nerve block and nerve trunk block can be applied according to the innervation of the pain site. It has been reported that within 3 months after the onset of herpes zoster, 70%-80% of patients with sympathetic nerve block can have their pain reduced, but the effect of nerve block is significantly reduced in patients with refractory postherpetic neuralgia of longer duration. 3.Epidural/subarachnoid drug infusion channel placement By giving epidural/subarachnoid channel placement, drugs may enter the epidural or arachnoid space directly, thus improving the efficacy of opioids and reducing the side effects of nausea, vomiting, constipation, urinary retention, etc. caused by the massive use of opioids. Pain can usually be effectively reduced by single push and continuous infusion of drug administration. 4.Other For refractory PHN, it can also be treated by total spinal anesthesia and peripheral electrical nerve stimulation.