DEMENTIA RESULTING FROM DURAL ARTERIOVENOUS-FISTULAS - THE PATHOLOGICAL FINDINGS OF VENOUS HYPERTENSIVE ENCEPHALOPATHY

PURPOSE: Dural arteriovenous fistulas (DAVFs) are acquired arterioveno us shunts located within the dura. The highly variable natural history and symptomatology of DAVFs range from subjective bruit to intracrani al hemorrhage and are related to the lesion's pattern of venous draina ge and its effect on the drainage of adjacent brain. We examined the p revalence and features of DAVFs in patients with progressive dementia or encephalopathy. METHODS: The records and radiologic studies of 40 c onsecutive patients with DAVFs treated at our institution were reviewe d. RESULTS: Five (12.5%) of 40 consecutive patients with DAVFs had enc ephalopathy or dementia. In each patient, high flow through the arteri ovenous shunt combined with venous outflow obstruction caused impairme nt of cerebral venous drainage. Hemodynamically, the result was widesp read venous hypertension causing diffuse ischemia and progressive dysf unction of brain parenchyma. Results of CT or MR imaging revealed abno rmalities in each patient, reflecting the impaired parenchymal venous drainage. Pathologic findings in one patient confirmed the mechanism o f cerebral dysfunction as venous hypertension. The hemodynamic mechani sm and resulting abnormality appeared identical to that seen in progre ssive chronic myelopathy resulting from a spinal DAVF (Foix-Alajouanin e syndrome). Remission of cognitive symptoms occurred in each patient after embolization. CONCLUSION: Venous hypertensive encephalopathy res ulting from a DAVF should be considered a potentially reversible cause of vascular dementia in patients with progressive cognitive deficits.