Patching these holes can stop or at the very least reduce the pain of migraines. Over a quarter of us have an opening in the wall separating the upper chambers of This opening, known as a patent foramen ovule, is a relic of our days in the womb, where it allowed blood to bypass the lungs. This ovule should typically snap shut with a baby's first breath, but it does not always close up completely.
Large holes can continue to allow small amounts of blood from the veins to bypass the lungs.
The most severe migraines tend to occur in those patients who have these holes. This means that any bubbles that form in veins as divers ascend can pass through the hole and enter the arteries, where they can block capillaries in the brain or spinal cord. Ordinarily, the lungs would simply filter out such bubbles. This is not the case when the diver has these larger holes on his heart. Additionally, Dr. Wilmshurst noticed that these divers tend to have a history of migraines.