Does skin temperature difference as measured by infrared thermography within 6 months of acute herpes zoster infection correlate with pain level?

Background Changes in the temperature distribution of the skin follows herpes zoster (HZ). Infrared thermography is a non-invasive, non-ionizing diagnostic tool that provides information about normal and abnormal functioning of the sensory and sympathetic nervous systems. This study examined the usefulness of infrared thermography as a predictor of post-herpetic neuralgia (PHN). Methods Infrared thermography was performed on the affected body regions of 110 patients who had been diagnosed with acute HZ. Demographic data collected included age, gender, time of skin lesions onset, development of PHN, and comorbidities. The temperature differences between the unaffected and affected dermatome were calculated. Differences > 0.6 degrees C for the mean temperature across the face and trunk were considered abnormal. Results The affected side was warmer in 35 patients and cooler in 33 patients than the contralateral side. A patient's age and disease duration affected treatment outcomes. However, the temperature differences were not correlated with pain severity, disease duration, allodynia, development of PHN, and use of antiviral agents (P > 0.05). Conclusion A patient's age and disease duration are the most important factors predicting PHN progression, irrespective of thermal findings, and PHN cannot be predicted by infrared thermal imaging.