Sigmoid Sinus Dural Arteriovenous Fistula With Spinal Venous Drainage Manifesting as Only Brainstem-Related Neurological Deficits Without Myelopathy

A 69-year-old woman presented with an extremely rare sigmoid sinus dural arteriovenous fistula (AVF) with venous drainage into a spinal perimedullary vein manifesting only as brainstem dysfunction without myelopathy. Cerebral angiography showed retrograde venous drainage into both the brainstem and spinal cord through the ipsilateral bridging vein from the affected isolated sigmoid sinus. Magnetic resonance (MR) imaging showed a hyperintense lesion in the medulla oblongata and lower pons with increased apparent diffusion coefficient (ADC), and enhancement with contrast material. The dural AVF was successfully treated by transfemoral transvenous embolization from the contralateral side, but the hyperintense area and neurological symptoms persisted after the treatment. The neurological deficits were probably due to venous hypertension associated with accessory retrograde venous drainage into the brainstem. MR imaging enhancement of the lesion may be more closely related to the prognosis of neurological deficits than the ADC value.