Dissociation between pain and the nociceptive blink reflex during psychological arousal

Objective To investigate the effect of psychological arousal on pain ratings and the R2 component of the electrically evoked blink reflex to a ‘pure’ noiciceptive stimulus. Methods Pain ratings and R2 to a noiciceptive stimulus (pulse width 0.3 ms, 2 mA, delivered from a concentric electrode attached to the supraorbital region of the forehead) were investigated in 16 healthy participants before and during a serial subtraction task, and in 16 control participants who sat quietly during nociceptive stimulation. Results Pain ratings decreased whereas R2 amplitude increased during the serial subtraction task. Conclusions Supra-spinal rather than spinal mechanisms inhibited pain perception during psychological arousal. Moreover, psychological arousal facilitated the R2 component of the blink reflex to a nociception-specific stimulus. Significance Supra-spinal influences need to be considered during clinical evaluation of the trigeminal nociceptive blink reflex.