Neurosurgeon Gavin Fabinyi said surgery on the 47-year-old Lewis television sportscaster went well at Melbourne's Austin Hospital, the AP reports.
"I'm pleased to say Wally is looking good, he has come out of the operation and is still a bit sleepy," Fabinyi said. "The operation has gone well."
Lewis will spend the next five days recovering in hospital and then another five days in Melbourne before returning home. It could be up to 12 months before doctors know if the operation has been a complete success.
Lewis spent eight days at the hospital wired to monitors and having seizures induced to see whether the last-resort surgery was possible and if it would work.
His illness first became public in 2001 during a sports telecast on the Nine television network in Brisbane. He appeared in good health at the start of the program, but suddenly seemed confused and could not finish his sentences while reading a story.
Lewis was the Brisbane Broncos' inaugural captain and played 31 State of Origin matches for Queensland state between 1980 and 1991. He played 33 test matches for Australia and was captain 23 times, the first time in 1984.