Postherpetic neuralgia (PHN) is a painful condition that occurs when the dermal cells are rebuilt and repaired after the acute herpes zoster has subsided. After infection with varicella-zoster virus in childhood, the virus can be latent in the trigeminal ganglion or the dorsal root ganglion of the spinal cord and, if reactivated, can cause herpes zoster infection. Acute herpes zoster is rare in children, and the incidence of acute herpes zoster has been increasing significantly in patients on immunosuppressive drugs or cachexia. Clinical symptoms: 1. persistent or paroxysmal severe pain in the affected area 2 months or more after herpes zoster has been cured; there may be post-blister scabs or scarring in the affected area; 2. obvious sensory and tactile abnormalities in the affected area, most patients are characterized by clinical manifestations of nociceptive hypersensitivity, which can produce severe unbearable pain with light touch, and some patients are characterized by clinical manifestations of hyperalgesia and marked hypoesthesia; 3. 3. The nature of pain: spontaneous, knife-like or lightning-like attack pain or continuous burning pain, constrictive pain, most patients have severe and unbearable pain, very few patients lack typical neuralgia; 4. Local signs are: skin scarring, loss of normal skin pigmentation in the herpes area, hyperalgesia, nociceptive hypersensitivity, and abnormal pain sensation. In some patients with longer disease duration, the skin of the painful area is not different from the surrounding normal skin. The exact mechanism by which postherpetic neuralgia occurs is not fully elucidated, and in the same patient, one or several mechanisms may be involved and may change during the course of the disease. Therefore, the treatment of postherpetic neuralgia is very difficult. Early and effective treatment is important in the early stages of the disease. Treatment of postherpetic neuralgia 1. Drug therapy There are various drugs used to treat PHN, mainly anticonvulsants, antidepressants, nonsteroidal anti-inflammatory drugs, opioids, and Chinese herbal medicine for internal and external use. Gabapentin is an anticonvulsant drug, which has become the first choice for the treatment of neuropathic pain internationally because of its precise efficacy and low side effects. Pregabalin is another anticonvulsant in the clinical treatment of PHN, and its efficacy is comparable to that of gabapentin, but its first-level elimination kinetics makes the plasma drug concentration controllable, which is better than gabapentin in terms of therapeutic safety. 2.Nerve block Local anesthetics for intradermal injection or peripheral nerve trunk or plexus block, thus blocking the conduction of nociception to the center, breaking the vicious cycle of pain, and also blocking the reflex sympathetic nervous system hyperactivity, prompting local vasodilation, improving blood flow, and promoting tissue function recovery. Depending on the location of the pain, stellate ganglion block, epidural block, paravertebral nerve block, other nerve trunk and branch block can be chosen. 3.Neurodesis For refractory PHN, if the effect of various methods is not good or cannot be maintained, neurodesis can be used, mainly divided into chemical methods and physical methods. Alcohol, Adriamycin, phenol glycerin and phenol are the commonly used chemical destruction drugs. Radiofrequency thermal coagulation destruction is a new physical destruction technique developed in recent years, which has the advantages of less complications, accurate positioning, less trauma to the tissue and significant effect, and low recurrence rate of pain. 4.Neuromodulation The principle of this method is to stimulate the target nerve that can produce pain through electrodes, so as to produce numbness-like sensation to cover the pain area and thus achieve the purpose of pain relief.