Maldonado, 39, had a lesion removed from the base bone of her brain on September 11, reported People magazine.
"She's good. She's at home recovering, so we're hoping for the best," Thomas, 43, said.
"We don't know what's gonna happen. We're just glad the surgery went well. She has great doctors; she has a bunch of people supporting her."
The musician took a night off from bedside duty to represent his and his wife's animal advocacy charity, Sidewalk Angels, at the Samsung gala.
