Facial expressions modulate pain perception in patients with chronic migraine.

Aim: First, we investigated whether the exposure to different visual feedback conditions may modulate pain perception by means of visual induced analgesia in patients with chronic migraine. Second, to comprehend the way emotional face expressions could induce visual analgesia, we evaluated the degree of identification with the four experimental conditions.
Methods: In a 1 × 4 within-subject study design, 38 female chronic migraine patients were exposed to different visual stimuli - positive face, neutral face, negative face, and control (white screen) - during a migraine attack. Visual stimuli were presented 3 times in a randomized order (each condition lasted 40 seconds). Migraine pain ratings and identification scores were assessed immediately after the observation of each visual condition.
Results: We observed a significant difference in pain ratings between the positive (median: 30, 95% CI 26.69 to 38.20) and the negative (median: 30, 95% CI 33.09 to 44.13) ( z  = -4.46, p  < 0.0001) facial expressions or the neutral facial expression (median: 30, 95% CI 31.89 to 42.41) ( z  = 3.41, p  < 0.001). Participants identified more with the neutral face condition than with the other conditions.
Conclusions: Observation of a positive emotional face resulted sufficient to modulate pain perception possibly via the mediation of emotion regulation for positive emotions. This study paves the way for the integration of new cognitive behavioural interventions based on the adoption of visual induced analgesia to further control pain perception in chronic migraine patients.