Intracranial dural arteriovenous fistula (AVF) is a rare condition; it is usually described as an arterio-venous shunt within the dura with sinus or cortical drainage. AVFs can occur anywhere in the central nervous system. Most commonly, they are found at the transverse sinus, and this location is reported in 50% of all cases. Symptoms of the Dural AVFs vary widely according to their location. Progressive thalamic dementia due to venous hypertension of thalamic draining veins is an example. Herein, we present a patient with reversible progressive encephalopathy due to this pathology.  

This is a 55-year-old man who was admitted for progressive encephalopathy for 3 months. Inpatient work-up included a negative Computed Tomography of the head, unremarkable infectious, toxic and metabolic abnormalities including cerebrospinal fluid analysis, patient underwent MRI of the brain with contrast showing bilateral thalamic infarcts.  MR angiography showed dural AVF at the torcular herophili, with high-grade stenosis of the junction of straight sinus and torcula Herophili. The patient underwent cerebral angiography showing a complex dural AVF at the tentorium and left sigmoid sinus, this was with a retrograde venous arterialization through the internal cerebral veins, the straight vein and vein of Galen. Embolization of the fistula was done intra-procedurally, with a gradual improvement of his mental status over 4 months when followed up on in the office.  

Bilateral thalamic infarcts due to underlying venous hypertension caused by dural AVF can present as a subacute or even a chronic encephalopathy. Since the symptoms are not specific, the diagnosis might be challenging. This condition must be added to the differential list when no other obvious etiology can be found. Early diagnosis and management are generally associated with good prognosis.