An afferent arc in the trigeminal nerve (mainly V1), a reflex parasympathetic connection to the SSN in the pons and an efferent arc in the facial nerve, via the sphenopalatine ganglion (SPG) and greater superficial petrosal nerve, are thought to mediate CAS observed in the TAC’s and migraine, using vasoactive intestinal peptide (VIP) [31] and other neurotransmitters [32]. The gene discussed is VIP; the disease is migraine disorder.