"Gareth Thomas has sustained damage to an artery in his neck, this caused the symptoms that he experienced on Sunday night and resulted in his admission to hospital," said Wales Team Dr Professor John Williams. "Those symptoms have since resolved. He has undergone detailed investigations and has been reviewed by a consultant neurologist at the University Hospital of Wales on Tuesday.
"The damaged blood vessel now needs to be given time to heal before Gareth can resume training and eventually playing. We are expecting him to make a full recovery and it envisaged that he will be able to resume training after 10 to 12 weeks."
New Wales Coach, Scott Johnson, has not named Thomas in the team to play Ireland on Sunday, but was initially hoping his inspirational Captain could travel with the squad to Dublin and play a leadership role within the team.
"We need to do what is in the best interests of Gareth Thomas in this situation, listen to the doctors advice and leave him at home to rest," said Johnson. "We will all be thinking of him, but his personal health is of a much higher priority to us all than anything that can happen on a rugby pitch. We wish him a speedy recovery and hope to have him back with us soon."