Valeri has been sidelined since late November and was later diagnosed with an inflammatory condition affecting part of his brain.
“After further testing, Carl has shown significant improvement from last month,” Muscat said.
“We will continue to work closely with his doctors to monitor his condition, but we are still yet to determine when he can return to training.
“We should be in a position to give a further update in the next 10-14 days, but at present, his return date remains indefinite.
“Carl is very appreciative of the support he has received, and the respect of his privacy, during this time.”
Football Federation Australia