The woman without a history.

The differential diagnosis for altered mental status (AMS) is broad and aetiological pathologies can arise from nearly all organs and body systems. Further complicating the matter, the altered patient is poorly suited to provide a comprehensive and accurate historical account. Thus, the physician must rely on collateral information, laboratories and imaging, and their own clinical suspicion. We present the case of a 75-year-old woman, found prone in her home with AMS, who was unable to provide a history. As her hospital stay evolved, we were forced to consider the entire breadth of possible causes of AMS. Eventually, the patient was found to have cerebral venous thrombosis, the significant extent of which is rarely reported. During the course of caring for the patient, we were reminded of the importance of remaining unbiased and unanchored while attempting to identify the source of the patient's ailment. 2015 BMJ Publishing Group Ltd.