"We are and remain confident that Michael Schumacher will pull through and will wake up," his agent and spokeswoman, Sabine Kehm, said in a written statement.
"There sometimes are small, encouraging signs, but we also know that this is the time to be very patient," she added.
Schumacher, 45, slammed his head on a rock while skiing off-piste in the French Alps resort of Meribel on Dec. 29.
The seven-times world champion has been in a stable but critical condition since then in a hospital in the eastern French city of Grenoble where doctors started lowering his sedation at the end of January to wake him up from an artificial coma.
"It was clear from the start that this will be a long and hard fight," Kehm said.
"Michael has suffered severe injuries. It is very hard to comprehend for all of us that Michael, who had overcome a lot of precarious situations in the past, has been hurt so terribly in such a banal situation."