Magnetic resonance angiography of the human middle meningeal artery: implications for migraine

PURPOSE: To describe a novel noninvasive method for studying middle meningeal artery (MMA) diameter changes in vivo in humans. Dilatation of the MMA has been implicated in the pathophysiology of migraine headache, but no direct evidence has been obtained in humans. MATERIALS AND METHODS: The diameter of the MMA (the extracranial part) was measured in 19 healthy volunteers before and after administration of a vasodilator (nitroglycerin (NTG), 1.2 mg sublingually) known to provoke headache. We used magnetic resonance angiography (MRA) in combination with a 47-mm microscopy coil and a semiautomatic contour detection program. RESULTS: The diameter of the MMA was 1.5+/-0.26 mm (mean+/-SD) before and 1.79+/-0.30 mm after NTG administration. This increase was 20.1% (95% CI=12.9-27.3; P<0.001). The mean increase in subjects who developed headache (N=11) was 0.34+/-0.19 mm as compared to 0.22 mm+/-0.20 mm in the eight subjects who did not (95% CI for difference=-0.07 to 0.31; P=0.188). CONCLUSION: MRA in combination with a 47-mm microscopy coil is a novel, noninvasive method to measure changes in the diameter of human meningeal vessels, with potential applications for migraine and other fields of neurovascular research.