Clinton’s blood clot is lodged near the brain

The blood clot that led to Secretary of State Hillary Rodham Clinton’s hospitalization on Sunday is lodged in a vein behind her right ear, her doctors disclosed in a statement late Monday.

The doctors said the clot, called a right transverse sinus venous thrombosis, was discovered Sunday when Clinton underwent an MRI as a “routine follow-up” to the treatment she has been receiving for a concussion. The vein runs between the brain and skull.

Drs. Lisa Bardack with Mt. Kisco Medical Group and Gigi El-Bayoumi at George Washington University Hospital said in their statement that the clot was being treated with blood thinners. They did not predict when Clinton would be able to leave New York-Presbyterian Hospital, saying that she would be released “once the medication dose has been established.”

The clot didn’t result in a stroke or any neurological damage, the doctors’ statement said.

“In all other aspects of her recovery, the secretary is making excellent progress, and we are confident she will make a full recovery,” they said. Several independent medical experts agreed, based on what her doctors released, that she probably would not suffer any long-term damage.

Her doctors described Clinton as “in good spirits, engaging with her doctors, her family and her staff.”

Clinton suffered a concussion 21/2 weeks ago after she fell while she was battling a flu virus. She has made no public appearances since then, and was forced to miss congressional hearings exploring the terrorist attack that killed four Americans in Libya in September.

Before the statement was released, most medical speculation had focused on the possibility that the clot formed in her leg.

Clots in the leg are not uncommon and pose risks largely because they can travel into the lungs, potentially causing severe distress or even death. Clots in the head are rarer.

Dr. Keith Black, chairman of the neurosurgery department at Cedars-Sinai Medical Center in Los Angeles, said the fact that the clot was only discovered during an MRI and that Clinton apparently had not suffered any symptoms were good signs that she was tolerating the condition. The risk can be further reduced with blood thinners, he said.

“She has tolerated the clot without any damage and that is a very good sign,” Black said. The vein where the clot formed is one of two channels that drain blood from the brain, so a clot on one side typically allows blood to continue to flow through the other side, he said.

Exactly why the clot formed was unclear. Blood clots can form because of dehydration, which Clinton suffered when she had the flu. But her type of clot is more often associated with a skull fracture, which she apparently did not experience. Dr. Benjamin Emanuel, an assistant professor of neurosurgery at USC, said her concussion could have been a factor in the formation of the clot. It is unlikely that the clot caused her to faint, he said.

The principal risk is not that the clot will break free and damage her heart or lungs, Emanuel said, but rather that it will continue to grow and further block the circulation of blood through the brain. In that case, a seizure, brain swelling or stroke could occur, he added.

The use of blood thinners is a standard treatment, typically lasting anywhere from one to six months, but it also can be something of a double-edged sword.

Dr. Neil Martin, chairman of the neurosurgery department at UCLA’s Geffen School of Medicine, said blood thinners could increase the risk of bleeding in the brain if the concussion damaged or bruised other blood vessels in her brain. But Martin added that usually a brain scan to look for such risks would be conducted before blood thinners are administered.

Clinton is in her final weeks as secretary of State. President Obama has chosen Sen. John F. Kerry (D-Mass.) to succeed her.

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paul.richter@latimes.com

ralph.vartabedian@latimes.com