Letter to the Editor Regarding "Determining the Definitive Time Criterion for Postherpetic Neuralgia Using Infrared Thermographic Imaging".

Key Summary Points

To the Editor,

We read the article written by Juhee Park and colleagues [1] with great interest. In the study, infrared thermal imaging (IRT) technology had been administered to determine the definite time criterion for postherpetic neuralgia (PHN). The technology analyzed skin temperature to estimate the timepoint when zoster-induced skin inflammatory reaction ended. They concluded that PHN associated with pathophysiologic change might be defined as 12 weeks after the skin rash. This finding provides a theoretical basis for the timing definition of PHN, and it is consistent with the team’s previous research results [2]. However, several aspects of this study should be clarified and discussed.

First, in the methods section, the author listed the inclusion criteria, which included patients complaining of herpes zoster with craniocervical and thoracic dermatome. However, in the conclusion section, was it appropriate to conclude that the time for PHN was defined as 12 weeks for all patients?

Second, as described by the authors, IRT is an effective diagnostic method for diseases such as complex regional pain syndrome (CRPS), neuropathic pain, headache, and myofascial pain [3, 4]. In addition, diabetic peripheral neuropathy and primary hyperhidrosis [5] also manifested body surface temperature changes. However, the study did not exclude patients with such comorbidities, which might have an impact on the final results.

In the methods section, is it appropriate to conclude that the time for postherpetic neuralgia is defined as 12 weeks for all patients?

The study did not exclude patients with some comorbidities.