Postherpetic neuralgia (PHN) is the most frequent complication of herpes zoster(HZ) and is defined as pain persisting for >1month after the healing of herpetic skin lesion or pain persisting for > 3 months following the onset of HZ. PHN manifests as spontaneous throbbing, stabbing, or burning, usually accompanied by various abnormal sensory symptoms , which affect 5-20% of patients with HZ. Due to the lack of accurate and objective auxiliary examination tools, it is difficult for diagnosis and treatment of PHN. As a non-invasive examination method, infrared thermal imaging (IRT) can play a role in the diagnosis and treatment of neuropathic pain by objectively reflecting the changes and distribution characteristics of human body surface temperature. However, there are few studies on the relationship between clinical phenotype and thermal infrared image temperature changes in PHN patients, and the relationship between the thermal pattern of skin temperature and the duration of disease and treatment progress in PHN patients has not been fully elucidated. This study was conducted to investigate the relationship of thermal imaging data with the duration of the disease, clinical phenotype, treatment effect, in order to explore the role of infrared thermal imaging in the diagnosis and treatment of PHN. Methods：all PHN patients will included. At each visit, a pain NRS score was performed, and clinical phenotypes were tested and labeled, including: allodynia, numbness, itching, heat sensation, cold sensation, and the most painful area(MPA). Infrared thermal imaging was performed, the Average Relative Temperature (ART) within the affected area and the contralateral area was compared. The relationship between the temperature change and duration of the disease, clinical phenotype, treatment effect was assessed.

patients with the follow conditions were excluded: 1)The skin area was lesions because of other disease(trauma, inflammation, skin scar, skin disease, tumor, etc.); 2) history of psychiatric diseases, chronic pain. 3) inabilities to complete IRT examination.

Inclusion Criteria:

• 1) patients>18 years-old 2) pain lasts at least 1 month after lesion crusting 3) Agreed to participate the research

Exclusion Criteria:

• 1))the skin area was lesions because of other disease(trauma, inflammation, skin scar, skin disease, tumor, etc.); 2) history of psychiatric diseases, chronic pain. 3)inabilities to complete IRT examination. 4) Disagree to participate to the research

all PHN patients in our hospital