Stereotactic radiosurgery for the treatment of dural arteriovenous fistulas involving the transverse-sigmoid sinus.

Object: The aim of this study was to assess the efficacy and safety of radiosurgery for the treatment of dural arteriovenous fistulas (DAVFs) located in the region of the transverse-sigmoid sinus.

Methods: A series of 20 patients with DAVFs located in the transverse-sigmoid sinus, who were treated with gamma knife surgery between June 1995 and June 2000, was evaluated. According to the Cognard classification, the DAVF was Type I in four patients. Type IIa in seven, Type IIb in two, and combined Type IIa+b in seven. Nine patients had previously been treated with surgery and/or embolization, whereas 11 patients underwent radiosurgery alone. Radiosurgery was performed using multiple-isocenter irradiation of the delineated DAVF nidus. The target volume ranged from 1.7 to 40.7 cm3. The margin dose delivered to the nidus ranged from 16.5 to 19 Gy at a 50 to 70% isodose level. Nineteen patients were available for follow-up review, the duration of which ranged from 6 to 58 months (median 19 months). Of the 19 patients, 14 (74%) were cured of their symptoms. At follow up, magnetic resonance imaging and/or angiography demonstrated complete obliteration of the DAVF in 11 patients (58%), subtotal obliteration (95% reduction of the nidus) in three (16%), and partial obliteration in another five (26%). There was no neurological complication related to the treatment. One patient experienced a recurrence of the DAVF 18 months after angiographic confirmation of total obliteration, and underwent a second course of radiosurgery.

Conclusions: Stereotactic radiosurgery provides a safe and effective option for the treatment of DAVFs involving the transverse and sigmoid sinuses. For some aggressive DAVFs with extensive retrograde cortical venous drainage, however, a combination of endovascular embolization and surgery may be necessary.