Vascular headaches and cerebral circulation: an overview.

A complex network of neurotransmission systems underlies the control of the cerebral circulation. Classical neurotransmitters, vasoactive peptides and receptors have been found in cerebral arteries. Central and peripheral structures are also probably involved in the neurogenic control of the cerebral circulation. Vascular and neurotransmission changes reported in vascular headaches suggest that an alteration of the neurogenic control of the brain circulation may be implicated in vascular headaches. In particular, locus coeruleus, which may control the intracerebral adrenergic pathway, can induce vascular changes similar to those of migraine. Moreover, the trigeminal ganglion, which may induce the release of substance P, can change the extracranial and intracranial vasodilator activity. The vascular theory of migraine, proposed by Wolff, is re-evaluated on the grounds of a possible mediation of the vascular responses by neurotransmitters. It is hypothesized that a deficient modulation by enkephalins may cause alterations of locus coeruleus and/or trigeminal ganglion. The problem of pain in vascular headaches is also considered: whether it is of vascular origin or whether it is due to a dysfunction of the central nociceptive pathway. Knowledge of the neurogenic control of the cerebral circulation may be useful in understanding some pathogenetic mechanisms of vascular headaches.