Thermography and thermoregulation of the face

Abstract

Background: Although clinical diagnosis of thermoregulation is gaining in importance there is no consistent evidence on the value of thermography of the facial region. In particular there are no reference values established with standardised methods.

Methods: Skin temperatures were measured in the facial area at 32 fixed measuring sites in 26 health subjects (7-72 years) with the aid of a contact thermograph (Eidatherm). A total of 6 measurements were performed separately for the two sides of the face at intervals of equal lengths (4 hours) over a period of 24 hours. Thermoregulation was triggered by application of a cold stimulus in the region of the ipsilateral ear lobe.

Results: Comparison of the sides revealed significant asymmetry of face temperature. The left side of the face showed a temperature that was on the average 0.1 degrees C lower than on the right. No increase in temperature was found following application of the cold stimulus. However, a significant circadian rhythm with mean temperature differences of 0.7 degrees C was observed.

Conclusion: The results obtained should be seen as an initial basis for compiling an exact thermoprofile of the surface temperature of the facial region that takes into account the circadian rhythm, thus closing gaps in studies on physiological changes in the temperature of the skin of the face.

Figure 1

Adjustment of thermoregulation. The system contains 2 types of sensors, corresponding to the internal and external thermoreceptors of the organism.

Figure 2

Measuring sites in the facial and neck regions and reference site (glabella) 1. Glabella. 2 Root of the nose. 3 Tabula frontale right (R). 4 Tabula frontale left (L). 5 Foramen supraorbitale R. 6 Foramen supraorbitale L. 7 Ramus temporalis R. 8 Ramus temporalis L. 9 Foramen infraorbitale R. 10 Foramen infraorbitale L. 11 Upper lip R. 12 Upper lip L. 13 Temporomandibular joint R. 14 Temporomandibular joint L. 15 Lower lip R. 16 Lower lip L. 17 Foramen mentale R. 18 Foramen mentale L. 19 Ramus massetericus R. 20 Ramus massetericus L. 21 Ramus submandibularis R. 22 Ramus submandibularis L. 23 Ramus submentalis R. 24 Ramus submentalis L. 25 Ramus supraclavicularis post. R. 26 R. supraclavicularis post. L. 27 Ramus supraclavicularis ant. R. 28 R. supraclavicularis ant. L. 31 Wing of the nose R. 32 Wing of the nose L. Measuring sites with identical regions of innervation: 1^st Ramus trigeminus R: 3,5. 2^nd Ramus trigeminus R: 7,9,11. 3^rd Ramus trigeminus R: 13,15,17. Plexus cervicalis R: 19, 21, 23, 25, 27. 1^st Ramus trigeminus L: 4,6. 2^nd Ramus trigeminus L: 8,10,12. 3^rd Ramus trigeminus L:14,16,18. Plexus cervicalis L: 20, 22, 24, 26, 28.

Figure 3

Means (lines) and standard deviations (bars) of temperature changes following application of a cold stimulus (n = 26). Isoline (0°) indicates mean data from the reference points (glabella). 32 measuring sites are grouped in 8 sites with identical regions of innervation in branches of the trigeminus nerve (V 1–3) and the cervical plexus (Pc) for the right and left side. Overall positive regulation in the areas of distribution of the 1^st and 3^rd branches of the trigeminus nerve on both sides, no regulation in the other areas. No significant thermoregulation in any area.

Figure 4

Means (lines) and 95% confidence intervals (bars) for facial skin temperature at the 8 grouped measuring sites at 2 a.m. and 10 p.m. as an example of a circadian rhythm of the facial skin. Abbreviations follow fig. 3.

Figure 5

Comparison of the means (lines) and standard deviations (bars) of temperature differences between the right and left sides at the 8 grouped measuring sites before and after application of a cold stimulus for all measurements. References are the measurements of the right sides (red isoline). Abbreviations follow fig. 3. Temperature on the left side of the face being in a mean 0.1°C lower than that on the right side (p = 0,05), before and after application of the cold stimulus.