The persistent foramen ovale and migraine

Foramen ovale perméable et migraine

Recent epidemiological data suggest a bidirectional link between patent foramen ovale (PFO) and migraine with aura (MA) with a relative risk of 2 for PFO in subjects with MA and for MA in subjects with PFO. There is no evidence for a link between PFO and migraine without aura. This link is not systematic and applies only to subsets of PFO, mostly large ones, and to subsets of patients with MA. Although comorbidity cannot be ruled out, it may be that this link is partly causal and that some large PFOs may favor MA attacks in genetically predisposed subjects, by allowing vasoactive substances, platelet emboli or paradoxical emboli to bypass the lung filter and trigger the cortical spreading depression of the aura. The first double blind randomised trial of PFO closure in refractory MA, "MIST", has failed to show a benefit on the primary efficacy end point: cessation of attacks during the analysis period included between 3 and 6 months after the procedure. There is thus at present no scientific reason to look for PFO or to close PFO in migraine patients.

New and future migraine therapy

Modern neuroscience advanced our understanding of putative migraine mechanisms, which led to improved therapeutics. Indeed, mechanism-based acute migraine therapy gained steam in the early 1990s after the introduction of the triptans (5-HT1B,D agonists). Post-triptans, novel targets such as calcitonin gene-related peptide (CGRP) antagonists, inhibitors of excitatory glutamatergic receptors, and nitric oxide synthase (NOS) inhibitors are leading the pack in this exploding field of discovery research. In contrast, novel therapeutic targets for migraine prevention are lacking despite a hugely unmet need. To date, migraine prophylactic drugs are advanced based on expanded indications for already approved pharmaceuticals (e.g., topiramate, valproate, propranolol, and timolol). An improved understanding of the predisposition to an attack, genomic discoveries, valid and reliable biomarkers and surrogates, and predictive preclinical models likely will unravel the neuronal substrates for central hyperexcitability and nociceptive dysmodulation, hopefully leading us to better mechanism-based targets for prevention, and ultimately yielding drugs with optimal therapeutic ratios or indices.