Speaking to "CBS Sunday Morning," Clarke, who is known for playing “The Mother of Dragons” Daenerys Targaryen on the popular HBO show, recalled the moment she realized she was suffering more than just a bad headache.
“Basically, I was in the gym, the most excruciating pain, like an elastic band just went, like, snap in my head. I felt an enormous amount of pressure suddenly, and then very, very, very quickly I realized I couldn't stand and I couldn't walk, and in that moment I knew I was being brain damaged,” she said of her first aneurysm.
In an essay published in March by the The New Yorker titled, "A Battle for My Life," Clarke, 32, revealed she almost died while filming the show.
In February 2011, just as "Thrones" was premiering, Clarke underwent her first of two brain surgeries and an extensive and grueling recovery period.
While working out with her trainer in London, she suffered from a ruptured brain aneurysm. At 24 years old, she says she "started to feel a bad headache coming on" but pushed through only to collapse in the bathroom. After being rushed to the hospital and having an MRI, the results were dire.
"The diagnosis was quick and ominous: a subarachnoid hemorrhage (SAH), a life-threatening type of stroke, caused by bleeding into the space surrounding the brain," she detailed in the article. "I’d had an aneurysm, an arterial rupture. As I later learned, about a third of SAH patients die immediately or soon thereafter. For the patients who do survive, urgent treatment is required to seal off the aneurysm, as there is a very high risk of a second, often fatal bleed. If I was to live and avoid terrible deficits, I would have to have urgent surgery. And, even then, there were no guarantees."
Eventually, she was able to return to the “Game of Thrones” set. But in 2013, the star learned she had another “smaller aneurysm” that she was told could “pop” at any time. She then underwent a second surgery.
"The recovery was even more painful than it had been after the first surgery. I looked as though I had been through a war more gruesome than any that Daenerys experienced. I emerged from the operation with a drain coming out of my head. Bits of my skull had been replaced by titanium," she wrote.
Clarke also told the network’s morning show part of her brain “died” following the second aneurysm.
"With the second one, there was a bit of my brain that actually died. If part of your brain doesn't get blood to it for a minute, it will just no longer work. It's like you short circuit. So I had that,” she said.
“There was a deep paranoia. I was like, 'What if something has short-circuited in my brain and I can't act anymore?' I mean, literally, it's been my reason for living for a very long time,” she went on, adding she “found it much harder to stay optimistic” the second time.
That said, the 32-year-old said she found strength in her “Thrones” character during recovery.
"But then you go on set and you play a badass and you walk through fire, and that became the thing that just saved me from considering my own mortality."
Thankfully, Clarke said in the New Yorker essay she “survived," adding “in the years since my second surgery I have healed beyond my most unreasonable hopes. I am now at a hundred percent.”
Clarke also told the news station she is “completely in the clear” regarding her brain health.
Fox News' Jessica Napoli contributed to this report.