Cerebral venous thrombosis and "Dense Triangle Sign" on unenhanced head computed tomographic scan.

This case report describes a 21-year-old man with headache who was ultimately diagnosed as having cerebral venous thrombosis(CVT), a rare cause of headache in the emergency department that is sometimes lethal. However, correct diagnosis of CVT is often quite difficult because of a lack of findings in imaging studies. Unenhanced head computed tomography was completely normal in up to 39% of patients diagnosed as having CVT, but a subtle sign known as 'Dense Triangle Sign' was found in this case. This finding disappeared after anticoagulation therapy. Emergency physicians must know about this finding to diagnose this rare condition correctly.