A big setback for England and the player, but at least Stuart Lancaster appears to be taking the issue seriously.
Mike Brown now looks unlikely to feature against Ireland at the Aviva Stadium this Sunday, after suffering a setback on his return from concussion.
Brown suffered the horrific injury after colliding with the shoulder of Italian Andrea Masi nine days ago, and was coming through the return to play protocols last week.
However, after experiencing further concussion symptoms while riding a stationary bike on Friday, Brown sat out the remainder of the weekend, before restarting the return to play protocols today.
England coach Stuart Lancaster told BBC 5 Live that he'll be making a ruling on the player in the coming days.
"The decision will obviously centre around Mike's health and well-being first and foremost
"If he is good to go then I have a selection decision to make on the basis of [someone else's] opportunity to train and play fully in the squad during the first part of the week.
"The first decision will be whether he is medically fit and able to play in the game, and we will make that decision via the protocol."
It means that Saracens full-back Alex Goode looks likely to get a start this Sunday against Ireland, while England have called Worcester's Chris Pennell has been called up to the squad as cover.
