Cedeno was hit in the back of the head attempting to break up a double play in the fourth inning of Friday's game in Washington. He experienced limited symptoms initially and remained in the game, but got progressively worse after leaving the ballpark.
Cedeno hit .252 and scored 30 runs with 23 RBIs through the first half of the season. Chase d'Arnaud took his spot at shortstop in Game 1 of Saturday's doubleheader and Brandon Wood got the start at third base.
Pittsburgh recalled infielder Pedro Ciriaco from Triple-A Indianapolis to take Cedeno's spot on the 25-man roster. The 25-year-old Ciriaco played in 40 games for Indianapolis, where he hit .210 with 15 RBIs and 10 stolen bases.
He appeared in eight games last season for Pittsburgh and had three hits in six at-bats.