Background: A relation between migraine with aura and cardiac right-to-left shunts has been reported. Right-to-left shunts are also associated with stroke and certain forms of decompression illness. We investigated the effect of closure of right-to-left shunts on migraine symptoms.
Methods: A consultant neurologist, who was unaware of information about residual shunt, undertook a structured interview with individuals who had had transcatheter closure of an atrial septal defect or patent foramen ovale to assess how the procedure affected migraine symptoms.
Findings: 37 of 40 consecutive patients who had had a closure procedure (to permit resumption of diving after decompression illness in 29, after stroke when paradoxical thromboembolism was suspected in four, or to close a large atrial septal defect in four) could be contacted. 21 (57%) had a history of migraine before the procedure (with aura in 16, without aura in five). 11 individuals had fortification spectra in the period immediately after closure. During long-term follow-up, no migraine symptoms were reported by seven individuals who had previously had migraine with aura and three who had previously had migraine without aura. Eight others who had had migraine with aura before closure reported improvement in frequency and severity of migraines. Three (one migraine with aura, two migraine without aura) reported no alteration in migraine episodes.
Interpretation: These observations suggest a causal association between right-to-left shunts and migraine with aura. There may be a subgroup of patients who have severe migraine associated with a large right-to-left shunt in whom closure of the atrial defect may improve or abolish migraine.