Wallace suffered a Grade 3 concussion on February 23, 2008 after taking an unintentional elbow to the face from Sacramento's Mikki Moore.[2] It was his fourth concussion in as many seasons with the Bobcats.[2] It was not clear when he would return,[2] although Grade 3 concussions are defined by the American Association of Neurological Surgeons as ones that "involve post-traumatic amnesia for more than 24 hours or unconsciousness for more than five minutes. Players who sustain this grade of brain injury should be sidelined for at least one month, after which they can return to play if they are asymptomatic for one week."[3]