Alex Smith never received full clearance from a neurologist after suffering a concussion last Sunday and will miss tonight's game against the Bears, according to a report by ESPN. Backup Colin Kaepernick will make his first ever start in a game in which another backup, Jason Campbell, will start for the Bears because of a concussion suffered by Chicago starter Jay Cutler.
The 49ers have yet to confirm the report that Smith has been ruled out.
Three days after the concussion, Smith said he felt fine and he quickly received clearance from an independent neurologist at Stanford Hospital to return to practice on a non-contact basis. But he practiced throughout the week in a black jersey, a signal that he had not yet received the full clearance. It's not yet known what prevented Smith from gaining the full clearance.
The 49ers were expecting Smith to play since they gave him the lion's share of the practice snaps this week. Coach Jim Harbaugh did say that Kaepernick, who was 11-17 for 117 yards in relief of Smith against the Rams, got more snaps than usual.
"I think there's a lot of different scenarios this week and it's fluid and we've talked through them," offensive coordinator Greg Roman said Saturday. "It will change according to how the big picture changes and obviously the quarterback position is a huge piece of that."
Smith hasn't missed a start since separating his non-throwing shoulder Oct. 24, 2010 in a loss in Carolina. He absorbed two big hits to the head during a 12-play drive against the Rams last Sunday and reported blurred vision after the second hit. Smith said the concussion symptoms -- blurred vision, headaches and nausea -- were worse than those from a concussion he suffered last year. Smith played the following week after the Week 2 concussion in 2011.
-- Matt Barrows