Head trauma can cause blood in a venous sinus to clot, but it almost always has to be severe enough to cause a skull fracture, said Aaron S. Dumont, director of cerebrovascular surgery at Thomas Jefferson University in Philadelphia.
“It’s probably a coincidence,” he said of Clinton’s fainting spell and the clot.
(Hillary Clinton's Blood Clot Could Have Been Life Threatening
)"She is lucky being Hillary Clinton and had a follow-up MRI -- lucky that her team thought to do it," said Dr. Brian D. Greenwald, medical director at JFK Johnson Rehabilitation Center for Head Injuries. "It could have potentially serious complications."
According to Greenwald, the clot was most likely caused by dehydration brought on by the flu, perhaps exacerbated by a concussion she recently suffered.