Lions' Terrion Arnold: Sits out practice again Thursday

Arnold (concussion) didn't practice Thursday.

Arnold suffered a concussion Week 10 against Washington and didn't play this past Sunday against Philadelphia. He's missed the first two practices this week, so there's reason to be pessimistic about his chance of suiting up Sunday against the Giants. Rock Ya-Sin started at cornerback in Arnold's stead against the Eagles and will likely do so again Week 12 if Arnold remains out.