Leinster and Ireland flanker Sean O'Brien is being treated for an inner ear issue - vestibular impairment - which affects his balance. The province have not yet set a date for his return to play.
The Carlow native was replaced in Leinster's Champions Cup defeat to Wasps on November 15th with what appeared to be the symptoms of concussion.
Yet in an injury update released by Leinster Rugby on Monday afternoon details of the problem have been revealed.
"As outlined by head coach Leo Cullen, after further investigation during the Return to Play Protocols and having met with an ear specialist, Sean is now also being treated for an inner ear issue - vestibular impairment, which affects his balance," Leinster have said.
“He took a limited part in training today and will be assessed on an ongoing basis.
Meanwhile Richardt Strauss has passed the Return to Play Protocols after also playing last against Wasps, he trained on Monday and is available for selection this weekend for the Pro12 game against Glasgow Warriors.
Rob Kearney also trained on Monday and he too is expected to return from his hamstring injury lay-off for Saturday's game. Johnny Sexton is also available for selection.
Luke McGrath has a medial strain and is expected to be back in contention for the visit to Toulon.
While Noel Reid, who was stretchered off in the closing stages of last weekend's win over Ulster, hasn't broken any bone in his ankle but there is ligament damage. He is waiting for the results of a further scan before seeing a specialist later this week to decide on the best course of action.
