Spokeswoman Sabine Kehm said: "We cannot judge if these documents are authentic. However, the documents are clearly stolen."
She said authorities have been notified, and Schumacher's managers will "press for criminal charges and damages" if the documents and data are made public or even referenced in a report.
After waking from a months-long coma, the 45-year-old Formula One great was transferred last week from a hospital in Grenoble, France, to one in Lausanne, Switzerland, to continue recovery from a December 29 skiing accident.
A statement from his management company said: "We expressly advise that both the purchase and the publication of such documents and data is forbidden. The contents of any medical files are totally private and confidential and must not made available to the public.
"We will therefore, in every single case, press for criminal charges and damages against any publication of the content or reference to the medical file."