Coach Erik Spoelstra said Miller was improving, but will miss Thursday's game because the condition prevents him from flying. He already missed back-to-back games against Toronto and Sacramento after jarring collisions.
Miller had an X-ray and CT scan after being elbowed in the head on Feb. 15 at Indiana. It was the third game in a five-day span where Miller took a hit.
He was tested for a concussion after getting hit in the head at Detroit and checked again following a hard screen in the game against Boston.
Miller is averaging 5.9 points, less than half his career average of 13.4, since joining the Heat in the offseason.