Treatment of spinal dural arteriovenous malformations: a single center experience Andres RH, Guzman R, Remonda L†, Schroth G†, Widmer HR, Seiler RW and Barth A Departments of Neurosurgery and Neuroradiology† University Hospital, Berne, Switzerland

Spinal dural arteriovenous fistulas (Type I spinal AVM’s) Most common type of spinal vascular malformations (80%) Rare and often misdiagnosed entities Natural history: progressive myelopathy 50% of untreated patients disabled within 3 years Goal of treatment: definitive occlusion of the fistula Optimal treatment strategy has yet to be defined

Anatomy and pathophysiology AVM located in the dura of the nerve root and/or adjacent spinal dura Feeder: radicular artery Drainage: medullary vein -> retrograde filling of the coronal vein plexus Congestion and dilatation of the venous plexus Venous hypertension -> reduced perfusion, ischemia, edema

Treatment strategies Surgical treatment: hemilaminectomy and occlusion of the fistula Endovascular treatment: catheter embolization Combined treatment strategy

Spinal angiography

Surgical anatomy Fistula point

Surgical technique

Location of the fistula: thoracic: n=8, lumbar: n=3, sacral: n=1 Study design 12 patients with spinal dural fistulas treated in our institution from 1994 to 2004 9 men, 3 women Median age: 59.18 years Location of the fistula: thoracic: n=8, lumbar: n=3, sacral: n=1

Modified Aminoff-Logue grading scale Grade Gait Normal 1 Leg weakness, abnormal gait or stance, but no restriction of activity 2 Restricted activity 3 Requiring 1 stick for walking 4 Requiring 2 sticks, crutches, or walker 5 Confined to wheelchair Micturation Hesitancy, frequency, urgency Occasional urinary incontinence or retention Total incontinence or persistent retention

Results Patient # Age, Sex Localization Treatment ALS pre post Outcome 1 67, M Th 6 Surgical 6 2 + Endovascular (2x) 5 - 3 57, M Th 5 Combined 4 68, M L 1 Endovascular 59, M 76, F L 2 7 57, F 8 20, M Th 9 9 74, M Th 8 10 45, M 11 76, M Th 7 12 51, F S 2

Results Group n n (OC +) n (OC -) Surgical 3 Endovascular 6 4 2 Endovascular 6 4 2 Combined 1

Conclusions Both endovasular and surgical treatment of spinal dural AVFs resulted in occlusion of the fistula and in a good and lasting clinical outcome in the majority of cases. For successful surgical occlusion, interruption of the venous drainage on the intradural side of the fistula is mandatory. In specific situations, a combined neurosurgical and endovascular approach is required to achieve complete occlusion of the AVF. Embolization should be attempted at the time of diagnostic angiography if the lesion is endovascularly accessible.