Pain but no temperature sensations are evoked by thermal stimulation of cutaneous veins in man.

To test the hypothesis that the sensory innervation of veins subserves nociception exclusively, we studied pain and temperature sensations on intravenously applied thermal stimuli before and after blockade of either cutaneous or venous afferents in man. Intravenous cooling or warming of a cutaneous vein segment of the hand was associated with corresponding changes in skin temperature and evoked pain only after numbing the skin but temperatures sensations only after intravenous local anesthesia. Thus, the sensory elements of veins, probably polymodal nociceptors, convey pain only on thermal stimulation while coactivated cutaneous thermoreceptors are responsible for concomitant temperature sensations.