Non-sinus type of transverse sinus dural arteriovenous fistulas on the arachnoid granulation of the dural sinus wall.

Background: The etiology of a non-sinus-type dural arteriovenous fistulas (DAVFs) with shunt points located on the sinus wall, previously described as on-the-wall-type DAVFs, is unknown. Case Description: Two cases of non-sinus-type transverse sinus DAVF with a shunt point limited to the dural sinus wall, causing cortical venous reflux, were successfully treated with endovascular transarterial Onyx embolization. The Onyx cast showed multiple feeders from the occipital and middle meningeal arteries aggregated in the arachnoid granulation (AG), which dilated the draining vein. Conclusion: Non-sinus-type DAVFs with shunt points located on the AG may be one of the presentations of an on-the-wall-type DAVF.