Occasionally, emergency physicians see patients who present because they are unresponsive despite normal vital signs and an otherwise normal exam. You detect no drugs or alcohol on board. You suspect a psychiatric or malingering etiology, but aren’t sure. They seem non-responsive to voice and minimally responsive to very painful stimuli. Is this a case of psychogenic coma or true coma (with bilateral hemispheric dysfunction)?
What test can you do to reassure yourself that this may indeed be psychogenic coma?