George North will see a consultant neurosurgeon within the next 48 hours to help Northampton Saints assess when the Wales wing can return.
North was knocked unconscious in a collision with Nathan Hughes while scoring his second try in Northampton's Premiership win over Wasps on Friday.
Wasps forward Hughes will appear before a RFU disciplinary panel on Tuesday after being sent off.
North, 22, has been knocked unconscious three times in recent months.
He will not play in Northampton's Champions Cup quarter-final against French side Clermont on Saturday.
Former World Rugby medical adviser Dr Barry O'Driscoll has told the BBC he should not play again this season.
Former Scarlets wing North also suffered blows to his head in the autumn and again during the Six Nations.
He missed Wales' 12-6 win over South Africa in November after being concussed against New Zealand, and was then struck twice on the head while playing against England during the Six Nations.
North missed Wales' next match against Scotland after being given an "extended recovery period".