Specialized treatment for postherpetic neuralgia Postherpetic neuralgia (PHN) is a condition in which the lesions of herpes zoster have completely healed, but there is still persistent, severe pain. Many methods have been reported for the treatment of postherpetic neuralgia, such as nerve block therapy, radiofrequency therapy, patient-controlled analgesia (PCA), etc. Although they are still effective, they have the disadvantages of high technical requirements, high risk, many complications and adverse reactions, long treatment period and high treatment cost in clinical application, especially not applicable to outpatients.