The clinical significance of infrared thermography for the prediction of postherpetic neuralgia in acute herpes zoster patients

Background Infrared thermography is a non‐invasive diagnostic tool that provides information for damage to the nerve, there was some reports that thermal asymmetry of acute Herpes zoster (HZ) patients was significantly related to development of PHN. Objective To identify whether infrared thermography is useful as a predictor for the development of postherpetic neuralgia (PHN) and as an objective assessment tool of subjective pain in acute HZ patients. Methods Infrared thermography was performed on the affected body regions of 112 patients who had been diagnosed with an acute stage of HZ. Demographic and clinical data were recorded. Differences >0.5°C for the mean temperature across the face and trunk were considered abnormal. According to whether PHN developed or not, we analyzed the correlation of risk factors. Results The study consisted of a total of 112 subjects (46 males and 66 females) with an age range of 9–93 years. The following summarizes the analysis results. (1) As pain severity increased, the occurrence of PHN increased significantly. (2) In older patients, the occurrence of PHN was significantly higher. (3) As the temperature difference between the affected and contralateral dermatome (ΔT) increased, the occurrence of PHN increased significantly. (4) There is a statically significant association between diabetes mellitus and the occurrence of PHN. (5) There is no correlation between pain intensity and ΔT. Conclusion In this study, we showed that infrared thermography is useful as a predictor of PHN development in acute HZ patients but is not useful as an objective assessment tool for indicating subjective pain.