Injured Formula One legend Michael Schumacher was admitted to the Georges Pompidou European Hospital in Paris on Monday for a “secret treatment,” according to Le Parisien.

Without citing sources, the French newspaper reported that the seven-time F1 world champion was in the hospital to receive stem-cell transfusion treatment by Dr. Philippe Menasche, a clinical cardiac surgeon.

Schumacher was reported to have visited the hospital twice prior this year, and that he was to receive the treatment on Tuesday.

It's now been almost six years since Schumacher, who turned 50 in January, suffered the fateful skiing accident that left him with serious head injuries and out of the public eye.

In the time since, updates on his health have been few and far between, the most recent coming in July from current FIA President Jean Todt who said Schumacher continues to make progress during recovery. Todt was Schumacher's former boss when he ran Ferrari's F1 race team, and the two developed a close relationship throughout Schumacher's career.

Schumacher remains the most decorated F1 driver to date with 91 Grand Prix wins and seven championship titles. Six of the titles were for Ferrari between 1996 and 2006. His son, Mick Schumacher, has largely followed in his father's footsteps. Mick currently races in Formula Two and is part of the Ferrari Driver's Academy.