Comment to: The chemical mediators of some sclerotherapy complications (Les médiateurs chimiques dans certaines complications de la sclérothérapie), by Ferrara F, Ferrara G. Phlébologie 2012;65:27-31.

To evaluate the chemical reaction of the venous wall to different sclerosing agents, the Authors studied the level of blood histamine concentration before and 8-10 min after sclerotherapy injection into large 3-6 mm subcutaneous varices. A total of 45 sessions were studied: a solution of iodine 2% was used in 15 (group A), liquid 2% polidocanol in 15 (group B), polidocanol 0.5% foam in 15 (group C). Histamine basal level was 4.49, 4.48 and 4.52 µg/100 mL, respectively, while after injection an increase was found of 4.50 (102%), 4.42 (99%) and 4.46 (100%) µg/100 mL, respectively. No significant relationship was found between agents and reactions. In C group, 2 cases had visual symptoms, both showing an 150% increase in histamine. Migraine with aura seems to be associated with high hematic levels of histamine. High histamine levels caused by sclerotherapy may explain the visual symptoms frequently reported after treatments. In fact, histamine is a vessel vasoconstrictor (venous spasm) but also a small artery vasodilator (hypotension). It could, therefore, mediate these minor sclerotherapy complications. For this reason, an antihistaminic pre-medication could be justified. The recently suggested endotheline hypothesis could support this.