The patent foramen ovale-migraine connection: a new perspective to demonstrate a causal relation

Efficacy of patent foramen ovale closure for treating migraine: a prospective follow-up study

This study aims to evaluate the potential of percutaneous patent foramen ovale (PFO) closure to improve the headache in patients with migraine and PFO, and discuss the difference between the randomized controlled trials (RCTs) and the single-center studies. Patients of migraine with a large shunt of PFO, who experienced ≥2 headache attacks per month and failed ≥2 categories of standardized medication, underwent PFO closure in First Affiliated Hospital of Xi'an Jiao Tong University. The clinical outcomes, including frequency and duration of headache attacks, Headache Impact Test (HIT-6) score, and Visual Analogue Scale (VAS) score, were evaluated at 3, 6, and 12 months of follow-up after the PFO closure. The different efficacies of the clinical outcomes between patients with and without aura as well as different grades of PFO were also evaluated, respectively. 134 patients with migraine (39 male and 95 female) with PFO were enrolled, whose average age was 39.21±11.37 years. After PFO closure, there was a significant reduction in frequency and duration of headache attacks, HIT-6 score, and VAS score at 3, 6, and 12 months’ follow-up (p<0.001). Migraine was completely relieved in 54 (40.30%) patients during 12 months’ follow-up. The frequency of migraine was reduced by >50% in 44 (32.84%) patients at 3 months’ follow-up and increased to 48 (35.82%) at 12 months’ follow-up. 31.03% patients remained residual shunt after 6 months of closure with varying improvements of headache. This study confirmed that PFO closure can effectively reduce frequency and duration of migraine and improve quality of life, but the definitive indications and long-term effect still need further research.

Migraine with aura triggered by cardiac myxoma: case report and literature review

We present a new case of cardiac myxoma triggering migraine auras. A 52-year-old woman was suffering from migraine attacks with aura. Magnetic resonance imaging (MRI) showed no abnormalities. Subsequently, she had a minor stroke with multiple ischaemic lesions bilaterally on repeat MRI. An echocardiogram showed a myxoma of the left atrial wall. After removal of the myxoma she was free of symptoms. In the past, seven cardiac myxoma associated migraine patients have been reported. Other cardiac abnormalities, patent foramen ovale in particular, are known to be associated with migraine with aura. We attempted to compare the mechanisms by which cardiac myxoma and other cardiac abnormalities could trigger cortical spreading depression leading to migraine with aura.

The role of causal criteria in causal inferences: Bradford Hill's "aspects of association"

As noted by Wesley Salmon and many others, causal concepts are ubiquitous in every branch of theoretical science, in the practical disciplines and in everyday life. In the theoretical and practical sciences especially, people often base claims about causal relations on applications of statistical methods to data. However, the source and type of data place important constraints on the choice of statistical methods as well as on the warrant attributed to the causal claims based on the use of such methods. For example, much of the data used by people interested in making causal claims come from non-experimental, observational studies in which random allocations to treatment and control groups are not present. Thus, one of the most important problems in the social and health sciences concerns making justified causal inferences using non-experimental, observational data. In this paper, I examine one method of justifying such inferences that is especially widespread in epidemiology and the health sciences generally - the use of causal criteria. I argue that while the use of causal criteria is not appropriate for either deductive or inductive inferences, they do have an important role to play in inferences to the best explanation. As such, causal criteria, exemplified by what Bradford Hill referred to as "aspects of [statistical] associations", have an indispensible part to play in the goal of making justified causal claims.