He was asleep while they were getting down into his brain. Once they got past the dura, the brain does not feel pain.

They wanted him awake so they would know if they were going too far with the resection. The left parietal lobe controls speech and his right sided movement. They certainly didn't want him to wake up unable to move or communicate!

Once they finished with the resection, he was put under once again.

His head was also immobilized, so he couldn't move it by accident.