Smith (concussion) has been ruled out for the remainder of Monday night's game against the Saints, Tori McElhaney of the Falcons' official site reports.
Smith exited the contest in the first quarter after being down on the field for several minutes. An independent neurologist ruled that the outside linebacker had sustained a concussion, and he will not be allowed to return to the game. Smith will now enter the league's five-step protocol to return to full contact play.