The 45-year-old has been in a coma at the University Hospital in Grenoble since he hit his head on a rock while skiing off-piste in the French Alps on December 29 last year.
Reports emerged this week claiming that Schumacher's wife Corinna is planning to build a £10m hospital room at the couple's home, but Kehm has refuted the rumours.
"I can only say again - there are signs that give us encouragement," The Mirror quotes Kehm as saying. "The rumours that Corinna remodels her house to bring the supposedly 'hopeless case Michael' home, are absolutely groundless."
Fans of the former Ferrari driver reportedly sent in complaints to German magazine Die Aktuelle for publishing a story relating to Schumacher with the headline 'Awake!'.