The Minnesota Twins placed center fielder day disabled list with migraine symptoms Thursday.
Span has missed the Twins' past three games while dealing with symptoms stemming from a concussion he received in a home-plate collision with Royals catcher Brayan Pena on June 3.
He was placed on the seven-day concussion disabled list after the collision and then put on the 15-day DL on June 23.
The 27-year-old was activated August 2, but was not nearly as effective as he was prior to the injury, recording just two hits in nine games and dropping his average from .294 to .263.
Span has two homers and 15 RBI with a .331 on-base percentage in 65 games for Minnesota this season.
The Twins recalled infielder Luke Hughes from Triple-A Rochester to fill the vacated roster spot.
Hughes has a .233 average with three home runs and 15 runs batted in 61 games with the Twins this year.