The Bruins said a CT scan revealed a cartilage injury to the larynx after he was hit by a John Tavares shot in the first period of a loss to the Maple Leafs.
Miller stayed in a Toronto hospital overnight for observation before returning to Boston.
The team said Miller's status will be re-evaluated in about five weeks.
The team also announced it has recalled winger Ryan Donato from Providence. After being demoted to work on his game, Donato had five goals and four assists in 10 games with the AHL club.