Defense attorneys told a judge James Holmes couldn't attend a hearing that had been scheduled for Nov. 15.
They withheld details, saying they didn't want to reveal privileged medical or psychiatric information.
The judge postponed the hearing until Monday. Denver media outlets, citing unnamed sources, reported Holmes was injured when he hit his head on a wall, apparently intentionally.
Authorities wouldn't comment. Holmes is charged with fatally shooting 12 people and injuring at least 58 in a crowded theater in July.
(Copyright 2012 by The Associated Press. All Rights Reserved.)