An ex-girlfriend has set in motion a legal battle over whether 92-year-old billionaire Sumner Redstone, who controls Viacom and CBS, is able to make his own health care decisions. Manuela Herzer has portrayed the tycoon in court documents as a "living ghost" obsessed with sex and steak, and out of touch with his surroundings. Redstone has trouble controlling routine bodily functions and grasping the significance of what doctors tell him, Herzer maintained in a legal filing Tuesday. She is asking - after being ousted from his home last month - that the court leave her in charge of Redstone's health care decisions on the basis that he was not competent enough to sign a directive assigning a new person to the task.Attorneys representing Redstone countered in court documents Wednesday that Herzer's filing is part of a "financial agenda" angling for a share in his estate. Establishing that Redstone was not competent to make legal decisions about his health care could provide a foundation for a court challenge to any recent changes made to his will. "Ms. Herzer has been on a warpath," Sumner's lawyers said. "Why? Because she suspected that in the days or weeks following her removal from his home, Mr. Redstone would take action to amend his estate plan and that whatever benefit might have previously accrued to her might be eliminated." Forbes has estimated Redstone's worth at some $5.5 billion. Sumner is receiving "superior" health care and help from a dear friend, according to his attorneys.