What IS PFO?
PFO stands for patent foramen ovale, a hole in the wall that divides the right and left chambers of the heart. We all have a PFO during before birth, but it usually closes before birth. The right side of the heart receives blood and pumps it to the lungs for oxygenation. The blood then goes through the left side of the heart to be pumped to the brain and other organs. A PFO can allow blood that hasn't been oxygenated to get into the left side of the heart and pumped to the brain and other organs. If this happens, the body doesn't get enough oxygen. It's also possible that blood clots can pass through the PFO and cause a stroke. PFO is diagnosed with a TEE (transesophageal echocardiogram), which is performed by passing an ultrasound probe down the esophagus, near the heart to get better results than the traditional echocardiogram, performed with a standard ultrasound wand outside the chest.
PFO and Migraine:
Research has shown a higher prevalence of PFO among Migraineurs.3 Small observational and case-control studies indicate that patients with stroke of unknown origin have a higher incidence of patent foramen ovale.4 It's still under investigation whether PFO closure prevents recurrent strokes. It is also thought possible that blood without enough oxygen may trigger a Migraine when it reaches the brain. In the April, 2004, issue of Neurology, two groups of researchers from Belgium (Post, et al) and Switzerland (Schwerzmann, et al) studied whether percutaneous closure (closing the PFO by a technique that does not require a major surgical procedure) would lead to fewer Migraines.
The Belgian group gave a Migraine questionnaire to people after PFO closure.2 The Swiss group gave a questionnaire assessing the headache frequency and characteristics for the year before and after PFO closure.3 There was no appreciable affect on the non-Migraine headache patients. In both studies, the PFO closure was done because doctors suspected that a blood clot passing through the PFO might have caused a stroke. Frequency of Migraine was decreased in both studies after PFO closure. Only the Swiss study evaluated both Migraine attacks and non-Migraine headaches.
Implications of these Studies:
- These two studies add to evidence of a PFO/Migraine association.
- The number of people who had Migraine with aura in both studies was higher than in the general population.
- PFO closure was associated with reduction of Migraine symptoms in patients having Migraine with and without aura.
- In the second study, non-Migraine headaches were not affected by PFO closure.
- These studies are important because if PFO closure proves effective for Migraine prevention, that makes PFO a potentially correctable Migraine trigger.
- However, these studies do not support
PFO closure as a treatment for Migraine due to two major limitations:
- The studies were retrospective (they asked patients for information about their headaches that occurred in the past)
- The studies included only stroke patients. For more conclusive results, a study is needed to evaluate otherwise healthy Migraineurs and collect data in real time.
Diener et al summarize these studies and the current situation with Migraine and PFO closure quite well, "These studies, however, have major methodological limitations. Therefore patent foramen ovale closure cannot be recommended for the prevention of Migraine with aura... At present routine percutaneous closure of isolated patent foramen ovale cannot be recommended for patients with cryptogenic stroke. Patent foramen ovale closure should not be used for the prevention of Migraine."4
New trials underway:
Trials are now underway to compare Migraine patients who undergo PFO closure with Migraine patients who don't. The MIST trial is underway in England, and results are expected in the spring of 2006. MIST stands for Migraine Intervention with STARFlex® Technology. The STARFlex® Septal Repair implant is a small medical device made of specially developed knitted mesh and flexible metal frame used to close holes in the heart. The MIST II trial for the United States is is expected to begin enrollmentearly in 2006.
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1 Kondapaneni, MD, MPH, Pranathi. "Does the percutaneous closure of patent foramen ovale help the migraine sufferer?" American Academy of Neurology Patient Page.
2 Post, Martjin C.; Thijs, Vincent; Herroelen, Luc; Budts, Werner I.H.L. "Closure of a patent foramen ovale is associated with a decrease in prevalence of migraine." Neurology April, 2004:62:14391440.
3 Schwerzmann M, Wiher S, Nedeltchev K, et al. "Percutaneous closure of patent foramen ovale reduces the frequency of migraine attacks." Neurology 2004:62:1399-1401.
4 Diener, H.C;, Weimar, C.; Katsarava, Z. "Patent foramen ovale: paradoxical connection to migraine and stroke." Current Opinion in Neurology 2005