An unusual study by doctors treating blast victims at a field hospital in Iraq has found that ruptured eardrums may help reveal which troops are at risk of hidden brain injury. The finding is important because many such brain injuries have been missed in the past, especially when more severe or obvious wounds demanded attention. Researchers report their observation in a letter in Thursday's issue of the New England Journal of Medicine. Diagnosing brain injury, especially mild damage, is based largely on subjective symptoms like irritability and forgetfulness. Imaging tests like CAT scans do not help, and neurological function tests...