LOS ANGELES (AP) - A legal battle has begun over media mogul Sumner Redstone and control of the 92-year-old billionaire's medical care.

LOS ANGELES (AP) A legal battle has begun over media mogul Sumner Redstone and control of the 92-year-old billionaire's medical care.

Redstone's former companion Manuela Herzer says in a probate filing Wednesday that Redstone lacks the ability to make informed decisions about his care, but the mogul's lawyers say he remains in good health.

Herzer is seeking to maintain control of Redstone's medical care.

Redstone's lawyer, Gabrielle Vidal, calls Herzer's characterizations preposterous. A filing by Vidal states Redstone was evaluated by a doctor on Monday and found to be in good spirits and able to make his own decisions.

Redstone controls media companies CBS Corp. and Viacom Inc. through National Amusements Inc., which holds nearly 80 percent of the voting stock in both companies. Redstone hasn't joined an investor conference call since November 2014.