Objective: To compare abnormal intensity areas on intracranial magnetic resonance images (MRI) and the pattern of venous drainage in dural arteriovenous fistulas (DAVFs) with retrograde venous drainage.
Methods: Thirteen patients with retrograde venous drainage of DAVFs were divided into two groups based on the venous drainage pattern determined by detailed angiographic and MRI study. In group 1 there was an accessory route draining into another sinus besides the main draining sinus. In group 2 no such accessory route was present.
Results: In group 1 patients (n = 8), MRI detected no unusual intensity areas; 5 patients in this group had episodes of bleeding. Angiographically, in this group retrograde venous drainage tended to occur via multiple varices. On the other hand, none of the 5 group 2 patients experienced a bleeding episode. Angiographically, there was a low incidence of varices. On T2-weighted images, these patients had a hyperintensity area. Following treatment, these areas of abnormality disappeared on T2-weighted MRI.
Conclusion: Among 13 patients with DAVFs which drained retrogradely, those with a variceal accessory route (Group 1, n = 8) had a higher incidence of haemorrhage. In patients without such an accessory route (Group 2, n = 5) abnormal signal intensity on MRI was indicative of venous congestion. Continuous-mode angiography and MRI study were useful in the precise identification of DAVFs with a venous drainage route.