The rapper - real name Earl Simmons - underwent testing on Wednesday following his heart attack
A Thursday report claims DMX has 'not regained any brain function' since he went into a coma
His family are said to be now faced with the agonizing decision 'to take him off life support'
Longtime friend and former manager Steve Rifkind has been asked to fly to New York on Friday to be by the 50-year-old rapper's side