Is migraine a disorder of the central nervous system?

The chicken and the egg problem is how, in Italian or in English, some time ago one would have referred to a question as the one to be approached here: "Is migraine a disorder of the central nervous system?" or of the peripheral nervous system? Till some time ago, even an honest basic scientist or clinician could almost equally sustain one or the other origin and find data that substantiate her/his opinion. Nowadays, however, our improved knowledge is pushing in the direction of the central nervous system, although many mechanisms remain unclear. The confusion originates from the important role played by multiple and important bidirectional interactions between the peripheral and the central nervous systems, i.e., the trigeminovascular system and the cerebral cortex. The problems are: Who starts first? Who is not working properly? It appears now that the answer to the question has to be probably searched in the delicate balance present in the central nervous system between excitatory and inhibitory circuits, their adaptation to chronic stimuli and, within these circuits, the balance of neurotransmitters, neuromodulators, transporters and ion channels that keeps them well functioning.