Making "Ocean's 12" was a labor of love for George Clooney, so when the star cancelled promotional appearances on shows like "The Late Show With David Letterman" and "Good Morning America," it was obvious he was really hurting. Now, for the first time, Clooney's camp has revealed just how serious the leading man's injuries were -- and it's much worse than first thought.

When "Extra" spoke with George last week, he was wearing a bandage around his neck, but always the gentleman, he downplayed his injuries, saying only, "I'm good. I'm fine now, had a little surgery over the holidays."

But we've learned the actor's condition was critical: he had neck surgery, followed by massive headaches. Doctors then discovered he had fluid leaking from his spinal column and performed a spinal cap.

Clooney reportedly hurt his neck while shooting a fight scene for his upcoming movie "Syriana," which co-stars "Ocean's 12" buddy Matt Damon. We've learned Clooney wanted to promote "Oceans 12" in Europe so badly that he drove to the airport, but was in such excruciating pain that he was forced to cancel the trip at the last minute.

But since Clooney's spinal cap, he told us he's doing a lot better, and was certainly well enough to joke about his pain, saying, "They just take a thing and they pull it to make you look younger. I'm okay."