Purpose: With highly portable mobile infrared cameras thermal imaging during acute stroke triage has become possible. The purpose of this pilot study was to evaluate the pattern of superficial facial skin temperature in patients with acute proximal arterial occlusion of the anterior circulation compared to non-ischemic controls. We hypothesize, that temperature dysregulation in stroke with associated thermal pattern may be used to predict presence of proximal vessel occlusion.
Methods: In 46 patients suffering from acute occlusion in the anterior circulation (ICA: 17, M1-MCA: 13, M2-MCA: 16) infrared thermal imaging of the face was performed before endovascular treatment. Asymmetric temperature patterns were evaluated visually. Quantitative temperature values were obtained from regions of interest (ROIs) placed symmetrically on the left and right half of on the facial thermal image. Presence and side of vessel occlusion was correlated with temperature measurements.
Results: Regional facial asymmetric temperature was readily visible at 0.5°C. Temperature differences ranged from 0.5 to 1.5° C in stroke patients, and <0.5°C in controls. In 16 of 17 patients with ICA occlusion, facial asymmetric temperature was detected (in 13 lower temperatures on ipsilateral side, in 3 on the contralateral side). In 11 of 13 patients with M1-MCA occlusion, facial asymmetric temperature was detected (in 8 lower temperatures on the contralateral side, 3 on the ipsilateral side). In 15 of 16 patients with an occlusion of M2-segment, asymmetric temperature pattern was apparent, however no clear trend with regard. In 16 of 20 controls, no asymmetric temperature pattern >0.5°C was observed.
Conclusion: Thermal imaging could serve as a fast point-of-care test to detect asymmetrical pattern in facial temperature as a predictor of proximal vessel occlusion in stroke. However, the current method is prone to imaging artifacts and reliability of detected asymmetry is moderate.