The NFL has agreed to remove a $675 million cap on damages from thousands of concussion-related claims after a federal judge questioned whether there would be enough money to cover as many as 20,000 retired players.

A revised settlement agreement filed in federal court in Philadelphia also eliminates a provision that barred anyone who gets concussion damages from the NFL from suing the NCAA or other amateur football leagues.

More than 4,500 former players have filed suit, some accusing the league of fraud for its handling of concussions. They include former Dallas Cowboys running back Tony Dorsett and Super Bowl-winning Chicago Bears quarterback Jim McMahon, who suffers from dementia.

"This agreement will give retired players and their families immediate help if they suffer from a qualifying neurocognitive illness, and provide peace of mind to those who fear they may develop a condition in the future," plaintiffs' lawyers Christopher Seeger and Sol Weiss said in a statement.

The original settlement included $675 million for compensatory claims for players with neurological symptoms, $75 million for baseline testing and $10 million for medical research and education.