GREEN BAY, Wis. -- Sam Shields, who sustained his fourth concussion in the last six seasons, underwent an examination by an off-site specialist this week to help determine the severity of the cornerback’s head injury.

But Green Bay Packers coach Mike McCarthy did not offer any other details about Shields’ recovery or prognosis.

“Sam is going through the protocol and the evaluations that are necessary with that,” McCarthy said Thursday.

Shields’ latest concussion came in the regular-season opener at Jacksonville and occurred less than nine months after his previous concussion on Dec. 13. Shields missed the final three regular-season games plus the NFC wild-card playoff win over Washington before he returned for the divisional playoff loss at Arizona.

This offseason, Shields called last year’s concussion “scary” because he doesn’t remember anything that happened.

"All I remember is going after the tackle and my head hitting the ground,” Shields said in June. “And that was it. I blanked out. I try to keep my head from getting in there, but it's kind of hard. It's a physical sport."

Shields also suffered a concussion in 2014 but returned the following week without missing a game. He missed one game in 2011 because of a concussion.

Shields is expected to miss his second straight game when the Packers host the Detroit Lions on Sunday.