Biochemistry of migraine.

The biochemistry of migraine is complex. Many contradictory or never replicated findings in often small patient groups have been published. The following observations in the platelet-free plasma and urine appear to have some solid basis and will be discussed: 1) systemic derangement of 5-HT metabolism, relevant to the peripheral vascular component of migraine pathophysiology, 2) changes in neuroexcitatory amino acids and magnesium, which may reflect a predisposition of the migraine patient, notably those having attacks with aura, to develop spreading depression, 3) alterations in methionine-enkephalin levels, which may be a useful marker to discriminate between tension headache and migraine, 4) hormonal fluctuations which seem important to set the threshold for an attack, 5) changes of vasoactive peptides in the cranio-vascular circulation, providing the first human evidence that the trigemino-vascular system indeed is relevant in migraine, and 6) catecholaminergic changes suggesting sympathetic overactivity. Finally distinct biochemical differences between patients with migraine without aura and patients with tension headache on one hand, and between patients with migraine with aura and patients with migraine without aura on the other hand will be emphasized. Findings in platelets will be discussed only if they are complementary and supportive to the plasma and urine data.