Visceral pain threshold is deeply lowered far from the head in migraine.

A short-lasting over-distension of the hand-forearm veins, obtained through a non-invasive original maneuver (Hand Arm Vein Distension test) induces local pain when applied to migraine sufferers in inter-critical period. Conversely, subjects with an absolutely negative personal and family history for any type of idiopathic headache do not report any pain or only an uncertain, slight one. The injection of 1 mL of 2% to 8% (i.e. 0.34 mol/L to 1.36 mol/L) hypertonic saline into the antecubital vein during an extemporary short (1 minute) circulatory blockage (ischemia induced to guarantee a strictly local action of the chemical stimulus) provokes moderate, strong or unbearable local (arm vein) pain in migraine sufferers but not in subjects with a personal and family history absolutely free from any type of headache. These results show for the first time that migraineurs show a proneness to visceral pain in viscera (veins) distant from the head (arm-hand). Such a finding is consistent with the theory that migraine pain is due to a central derangement of the viscerosensory system.