Frontal infrared thermography in healthy individuals and chronic migraine patients: Reliability of the method

Background The use of frontal infrared thermography in the diagnosis of primary headaches provided scattering results due to measurement fluctuations and different types of headaches or research protocols. Objective This study aims to assess the reliability of frontal infrared thermography in healthy individuals and provide a preliminary evaluation in chronic migraine patients using a commercial infrared thermal camera. Methods Thermographic images were acquired in 20 controls and 15 patients at three consecutive time-points in two daily sessions. The Side Difference and Asymmetry Index parameters were defined. The reproducibility of the measurements, the correlation of Asymmetry Index and Side Difference with clinical evaluations and patient perceptions, and the ability of the parameters to discriminate between patients and controls were investigated. Results We reported a good reproducibility of the measurements (Inter-class Correlation Coefficient > 0.75 and Coefficient of Variation < 13.4%), independent from external factors. The Side Difference was significantly different between patients and controls (  p < 0.001). The Asymmetry Index showed good correlation with the side of unilateral pain (  p = 0.0056). Conclusions Frontal infrared thermography can be used to quantify the difference between the right and the left side of frontal vascular changes in chronic migraine patients, provided that standardized conditions are satisfied.