Former Chiefs captain Craig Clarke has been forced to take an indefinite break from rugby are suffering 10 concussions in 22 months.
Clarke, 30, has been captaining Irish province Connacht this season after parting ways with the Chiefs following their second successive Super Rugby title win last year.
He suffered the concussions during the northern hemisphere season and in his final two seasons in Super Rugby, Connacht coach and former Blues coach Pat Lam told Irish website TheScore.
"Craig has had his tenth concussion in 22 months, so he is a big concern," Lam said.
"At this stage he is going to be unavailable indefinitely, until there is a bit more testing and so forth.
"It is obviously a big blow for us but you can just not mess around with that sort of situation.
“The players had a week off after the Saracens game but he was suffering even last week.
"Obviously we favour investigations but more importantly is just time."
Clarke signed a three-year deal with Connacht after leaving the Chiefs.
Co-captain with Liam Messam, he was instrumental in the New Zealand province's rise from conference wooden spooners to dominant power during the past three years.
His plight will draw further attention to the issue of concussion and head injuries in rugby.
Lam revealed he had seen former All Black Benson Stanley suffer the same scale of injury two years ago.
Stanley played 53 matches under Lam at the Blues before moving to France to play with Clermont.
"He was considering retiring and he just had to go through the timing and he was thinking about stepping down," Lam said.
"But through timing and treatment and rest he got through and he is playing at Clermont now, so we are hopeful."
- Sydney Morning Herald
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