Hillary Clinton remains hospitalized, but expected to recover

The Secretary of State has been undergoing treatment for a blood clot just below her ear that was reportedly caused by the concussion she suffered in mid-December. She is expected to make a complete recovery. NBC News chief science correspondent Robert Bazell reports.

By Maggie Fox and JoNel Aleccia, NBC News

Secretary of State Hillary Clinton remained hospitalized Tuesday for a blood clot in her head, but her doctors say she has no brain damage and is expected to recover completely.

Clinton, who fainted and suffered a concussion earlier this month, is being treated with blood thinners to help shrink the clot, which is in one of the veins between the brain and her skull.

"In the course of a routine follow-up MRI on Sunday, the scan revealed that a right transverse sinus venous thrombosis had formed,” Dr. Lisa Bardack of Mt. Kisco Medical Group in New York and Dr. Gigi El-Bayoumi of George Washington University said in a joint statement.

“This is a clot in the vein that is situated in the space between the brain and the skull behind the right ear. It did not result in a stroke, or neurological damage. To help dissolve this clot, her medical team began treating the secretary with blood thinners. She will be released once the medication dose has been established.”

Sec. of State Hillary Clinton was supposed to return to work later this week until doctors discovered a blood clot had formed in a vein between her brain and skull. NBC's Andrea Mitchell reports.

The statement helps answer questions about Clinton’s condition, outside experts said. “This is different than a lot of assumptions that people made, which is that it was a deep vein thrombosis in her leg,” said Dr. Alex Valadka, a spokesman for the American Association of Neurological Surgeons and a practicing neurologist in Austin, Texas.

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The statement from Clinton’s doctors suggested she would recover fully.

“In all other aspects of her recovery, the Secretary is making excellent progress and we are confident she will make a full recovery. She is in good spirits, engaging with her doctors, her family, and her staff,” they said.

Valadka said such a clot can be very dangerous.

“This could potentially be very serious because so much blood goes through your brain,” Valadka told NBC news. “If you block one of the major draining pathways, you can get a stroke.”

Valadka said standard treatment would be to infuse a bloodthinner such as heparin right away, and to then put a patient onto blood thinner pills for a fews weeks or months.

“The interesting question is how is this related to her concussion, if at all?” Valadka asked.

Clinton, 65, is known for hitting the road hard and she’s logged close to a million miles in travel, having visited 112 countries while in office. She had planned to step down in 2013 and was widely considered a potential front-runner for the Democratic nomination for president, if she chose to run again in 2016.

The extensive travel and dehydration could predispose someone to such a blood clot, Valadka said.

“These dural venous sinus thromboses, they can happen spontaneously on their own without any trauma, without any blow to the head,” Valadka said. “Is it just a coincidence?”

But a blow to the back of the head could have damaged the vein, causing the clot, he added.

Dr. Jack Ansell of the New York University School of Medicine agreed.

“This condition is certainly not common but it’s not rare, either, and certain patients are prone to it,” Ansell said. “They include those who have head trauma, as she did, and people who have other underlying tendencies to have blood clots. It’s a serious problem but it is certainly one that is eminently treatable. I would expect her get better.”