Wales captain Ryan Jones was ruled out of the remainder of the British and Irish Lions tour of South Africa on Friday just a day after joining the team as an injury replacement.
Jones was called up as cover for injured flanker Stephen Ferris, but neurological tests showed he was not in a fit state to play.
Jones underwent the same medical tests as all the Lions squad on his arrival but a further test by a neurosurgeon was sought and he recommended Jones did not play for three weeks after suffering two blows to the head during Wales's tour of North America.
Jones won three caps for the Lions in New Zealand in 2005 and has played in 33 tests for his country.
Head coach Ian McGeechan will not be seeking a further replacement.