Flanker Shane Christie won't play any Super Rugby this season, Highlanders coach Tony Brown has confirmed.
Christie, after co-captaining the Highlanders last year with All Blacks fullback Ben Smith, has been sidelined since the pre-season with a mystery illness.
His specific condition hasn't been diagnosed, but he has been experiencing concussion-like symptoms.
Christie's condition has been extensively managed by Highlanders medical staff, with support from New Zealand Rugby, and has included independent assessment of his situation.
In the interests of Christie's health, it has been decided to rule him out of selection so he can focus on his recovery, Brown said.
"It's unfortunate for the team and Shane that we won't see him in our colours this year, but we fully support the medical decision not to play to assist his recovery."
Christie will remain with the team as part of the leadership group for the rest of the season.