MMP9 and migraine disorder: Indirect evidence: no differences in MMP-9 and TIMP-1 levels were found between ictal and interictal periods. However, lower plasma levels of MMP-3 were observed in the external jugular and cubital vein during migraine attacks. Such results suggest that plasma levels of MMP-9 might not be the most recommended biomarker of BBB disruption in migraine without aura. On the other hand, MMP-3 levels should be further investigated.