I had one recently that the vet thinks "threw" a clot to her brain. She was ill and under the vet's care in the first place, but when I started noticing edema that wasn't going away, I took her back. On the way to the vet, she started biting the air, and writhing, and biting herself and acting "not there." Perhaps something similar happened with this snake and that's what the vet meant when he said something about her brain.