Parallel Venous Channel As the Recipient Pouch in Transverse/Sigmoid Sinus Dural Fistulae

OBJECTIVE: The most common location for dural arteriovenous fistulae (AVFs) is the transverse/sigmoid sinus. We describe our prospective analysis of data for 10 patients with recipient fistulae parallel to the transverse/sigmoid sinus. Recognition of this entity allows embolization of the fistula with preservation of the parent sinus. This report reviews the presentation and angiographic characteristics of the "parallel venous channel" and the treatment results for this series of patients. METHODS: Between 1995 and June 2002, at the medical center of the University of California, San Francisco, we identified 10 patients with a parallel venous channel as the recipient pouch for all arterial input into a transverse/sigmoid sinus AVF. The clinical presentations, angiographic features, endovascular treatments, and outcomes are described. Angiographic follow-up monitoring was performed for 1 to 6 years for all patients with cortical venous drainage (5 of 10 patients). Clinical follow-up periods ranged from 1 to 7 years. RESULTS: All patients presented with pulsatile tinnitus disruptive to sleep. Other symptoms included severe headaches, papilledema and visual disturbances, hemiparesis, and mastoid pain. All 10 parallel venous channels communicated with the transverse or sigmoid sinus. Cortical venous drainage was present in 50% of cases. Endovascular ablative procedures, using either coils or ethanol, were performed for all patients. The parallel venous channel was successfully embolized, with preservation of the transverse/sigmoid sinus, for all 10 patients. There were no major complications. All patients experienced resolution of their symptoms, with no recurrence. CONCLUSION: The existence of a parallel venous channel as the recipient pouch for all arterial inflow in a series of 10 transverse/ sigmoid sinus AVFs is described. Endovascular obliteration of the parallel channel, with preservation of the parent sinus, was successfully performed for all 10 patients. Recognition of the parallel venous channel is clinically important for the treatment of transverse/sigmoid AVFs.