Seahawks' Cade Johnson: Tests reveal concussion

Tests at Seattle's Harborview Medical Center revealed a concussion but no additional injuries for Johnson, who was transported to the hospital after exiting Thursday's preseason game against the Vikings, Brady Henderson of ESPN.com reports.

Johnson was wobbly after getting tackled on a kickoff return in the second quarter. He remained in the blue medical tent until halftime and was then transported to the hospital. It's encouraging that the extent of Johnson's injury was limited to the concussion, but it's too early to determine his recovery timeline at this point, and the receiver will have to clear the NFL's five-step concussion protocol before he can return to the field.