That means Spikes is eligible to participate in all playoff games, should the Patriots make the postseason. They own the AFC's best record at 10-2.
"I've been contacted by the NFL and informed that I will be suspended four games for the detection of an illegal substance in a drug test," Spikes said in a statement. "The substance was a medication that I should have gotten clarification on before taking. It was not a performance enhancer or an illegal drug. The integrity of the game is very important to me. I understand the league's ruling and apologize to my teammates, the fans and the Patriots organization for this mistake."