Vick took the test again on Wednesday and didn't pass. Nick Foles will take the practice snaps Thursday and is likely to start his third straight game.
The Eagles, who have lost seven straight games, will try to avoid their longest losing streak in 44 years when they face the Cowboys on Sunday.
Foles has thrown for 542 yards with one touchdown and three interceptions in three games since replacing Vick during a 38-23 home loss to the Cowboys on Nov. 11.
Vick spent Tuesday night being sized for a protective skull cap that he plans to wear under his helmet when he returns to play to safeguard against suffering another concussion.
At the urging of neurologist Dr. Dimi Barot, Vick met at his home with Unequal Technologies Corporation CEO Rob Vito to be measured for the new "dome'' device made of the company's Concussion Reduction Technology.
Vick had Unequal retro-fit his helmet with similar padding upon returning from a concussion in September 2011. The same company designed protective Kevlar devices that enabled Vick and Cowboys quarterback Tony Romo to play with serious rib injuries in recent seasons.
Information from ESPN NFL Insider Ed Werder and The Associated Press was used in this report.