LEARNING OBJECTIVES: 1) Recognize the clinical presentation of dural vein thrombosis. 2) Differentiate dural vein thrombosis among causes of headache with focal neurologic findings. CASE: A nineteen year-old female without significant past medical history presented three weeks postpartum with 17 days of headache which had become intractable and unilateral for the past week and associated with new onset diplopia. Past medical history was negative for any headaches, fevers, trauma or upper respiratory symptoms. Personal and family history were negative for thrombosis. She had an uncomplicated pregnancy and an unremarkable vaginal delivery. Her postpartum period was marked by a hospital admission for new onset headaches, new seizures and elevated blood pressure with a non-focal neurologic exam five days after delivery. Workup at the time revealed a urinalysis without proteinuria but Magnetic Resonance Imaging (MRI) of her brain had revealed bilateral increased cortical signal intensities suggesting eclampsia. She was discharged on antihypertensives and antiepileptics with a diagnosis of atypical eclampsia, only to return with worsening headaches not responding to hydrocodone and a new onset of diplopia one week later. Her physical examination revealed double vision worsened on left lateral gaze but was otherwise nonfocal. Cerebrospinal fluid examination revealed 7 red blood cells, 0 white blood cells, protein of 35 mg/dl and glucose of 53 mg/dl, with normal serum blood counts. A repeat MRI of the brain demonstrated left sigmoid vein thrombosis extending to the transverse vein and internal jugular vein and active infection of paranasal sinuses. The patient was started on broadspectrum antibiotics along with heparin for anticoagulation. Hypercoagulable workup was subsequently negative, and her diplopia and headache resolved within 2 weeks. DISCUSSION: Dural vein sinus thrombosis is an uncommon but challenging cause of headache that can cause blindness and permanent neurologic deficit in 6–20% and has mortality rate in excess of 10%. Although the disorder can occur at any age, postpartum females seem to be at higher risk, with an incidence of 8.9 per 100,000 births. Hypercoagulable states and direct extension of local infections such as sinusitis or mastoiditis are implicated as causes in the literature. Incidence of this disorder has dropped precipitously since the pre-antibiotic era. Physicians should consider dural sinus thrombosis in a patient with severe headaches resistant to usual analgesics, especially if proptosis, papilledema or focal neurologic signs are found or if associated with new seizures. Early recognition and treatment with anticoagulants is thought to be important to prevent morbidity and mortality.