NFL Commissioner Roger Goodell on Tuesday sent a memo to the 32 teams updating them on some of the new developments in the league regarding concussions. The most interesting thing in the memo was that concussion committee co-chairs Drs. Ira Casson and David Viano have offered their resignations and they have been accepted by the league.

Casson had come under fire by some critics for not attending recent Senate hearings on concussions in football, and NFL Players Association officials also had called for his ouster from leading the league’s concussion committee.

No replacements for Casson and Viano have been named, but Goodell in the memo said that the concussion committee will be strengthened and expanded with new medical experts in the near future.

• Read the league’s press release about Goodell’s memo to the teams.