Patriots running back TreVeyon Henderson did not travel to Munich for New England’s contest with the Lions on Sunday while he deals with an “unexplainable medical emergency.”

It will mark his third straight absence and second since the reveal of this condition.

Head coach Mike Vrabel confirmed that Henderson remained in the United States when the team flew to Germany on Thursday morning and said he’s been constantly checking in on the back.

“I talk to TreVeyon every day,” Vrabel said. “Just like everybody else that’s not available, he’s working hard to get back. And when that is, I don’t know. I don’t have a timetable. … But I love my interactions with him. I love talking with him and seeing how he’s doing.”

Last week, Henderson revealed that he spent multiple days in the hospital after an “unexpected and unusual medical emergency involving a series of unexplained neurological symptoms.”

Concerns were serious enough that doctors tested Henderson for a stroke.

Henderson missed the Week 8 win over the Dolphins with what the team labeled as an illness, and received the same designation for last week’s loss to the Packers.

The Patriots have not placed Henderson on injured reserve, and there is currently no timetable for when the second-year running back might return.

The Patriots are thin at running back at the moment.

Starter Rhamondre Stevenson returned to practice in a limited capacity Thursday with a knee issue, and it’s not yet clear if he’ll be good to go in Munich.

Should Stevenson be kept out, Corey Kiner and Lan Larison would take the reps in the backfield.

Henderson has 203 rushing yards and one touchdown through six games this season after bursting onto the scene as a rookie last season.