Thomas played every snap in Miami's loss last week to Dallas but said he felt "a little lightheaded" in the locker room after the game, coach Cam Cameron said. Thomas complained of a migraine Wednesday and missed practice, which led to the tests.
Thomas has fought migraine and concussion problems in the past but has missed only 13 games during a 12-year career. A decision on whether he can play this week is likely by Friday, Cameron said.
"In a lot of cases, the player wants to play," the coach said. "Sometimes you've just got to take a deep breath, and sometimes it's tough. You know what it means to lose a player like Zach Thomas. But there is a lot bigger picture out there that you are accountable to."
If Thomas doesn't play, outside linebacker Channing Crowder would start in the middle, and Donnie Spragan would likely move into the lineup on the outside.
"When you have a concussion or something, a new mouthpiece always fits tighter and you get a better grip on it," Porter said. "He had a mouthpiece, but he just wanted another one. A brand new one is harder. The old one, you tend to chew on it, and you wear it out a little bit."
Copyright 2007 by The Associated Press