PAINFUL VEIN OVERDISTENSION IN MIGRAINE PATIENTS - NO RELATIONSHIP WITH SEROTONINERGIC PARAMETERS

Overdistension of the hand-forearm veins after a period of ischaemia-i nduced stasis causes local pain in a high percentage of migraineurs, b ut never in healthy subjects. To investigate the mechanism of such pai n, we compared 5-hydroxytryptamine (5HT) whole blood levels and hand v ein 5HT reactivity of migraine subjects who did experience pain during venous overdistension to those who did not. No differences were found in whole blood 5HT levels or in the venoconstrictor activity of 5HT b etween subjects experiencing pain and those who did not. No correlatio n was found between whole blood 5HT levels and the degree of 5HT-induc ed venoconstriction. Our results suggest that, if platelets are consid ered as a model of central antinociceptive 5HT neurons, pain appearanc e is not due to reduced 5HT at a central level and, therefore, to incr eased perception of peripheral nociceptive stimuli. Moreover, the simi lar 5HT venoconstrictive effect (indirect marker of venous tone and, t herefore, of venous distensibility) seems to indicate that a mechanica l factor is not involved in pain appearance during the HAVD test.