Secretary of State Hillary Clinton has a blood clot behind her right ear in a vein between her brain and skull. Clinton's doctors say her blood clot did not result in a stroke, or neurological damage.
"This is something that is not affecting the brain tissue itself. Having said that, if the clot obstructed blood from out of her brain and become damaged," said Dr. Cathy Sila of University Hospital's Case Medical Center.
Doctors say it's key to stabilize the clot. They are treating it with blood thinners.
"It prevents the clot from getting larger," Sila said.
The 65-year-old suffered a concussion earlier this month after she fell at her home. She is also being monitored for other conditions related to her concussion.
"Sometimes when people have concussions they have pretty bad headaches, dizziness and vertigo," Sila said.
Depending on the severity of the concussion, symptoms can last a couple of weeks.
Clinton's doctors say she is in good spirits engaging with her family and staff and is making excellent progress.
Some risk factors for blood clots include prolonged bed rest, sitting for long periods of time, being over age 60, pregnancy and smoking.