Angiographic changes in venous drainage of cavernous sinus dural arteriovenous fistulae after palliative transarterial embolization or observational management: a proposed stage classification.

OBJECTIVE: We assessed whether angiographic changes in venous drainage patterns occur over time in cavernous sinus dural arteriovenous fistulae (dAVFs) without a complete cure.

METHODS: We classified 65 cavernous sinus dAVFs into three types on the basis of initial angiographic findings. In Type 1, both anterior and posterior drainage routes were open; in Type 2, the posterior drainage route was closed, whereas the anterior drainage route was open; and in Type 3, both the posterior and anterior drainage routes were closed.

RESULTS: Of the 65 dAVFs, 40 were of Type 1, 21 of Type 2, and 4 of Type 3. During the follow-up period, 17 of the dAVFs that were treated palliatively with transarterial embolization (n = 11) or monitored without therapy (n = 6) demonstrated angiographic changes. In these 11 patients, there was a change in the venous drainage pattern from Type 1 to Type 2 (n = 5), from Type 2 to Type 3 (n = 3), and from Type 1 to Type 3 (n = 3). One of 11 had a conversion into a lesion with cortical venous drainage. The remaining 6 dAVFs (4 with observational management, 2 with transarterial embolization) demonstrated closure of the fistula; in 5 of these, the affected cavernous sinus was not depicted on follow-up angiograms.

CONCLUSION: In some cavernous sinus dAVFs with palliative transarterial embolization or observational management, there was a change in the venous drainage patterns, consisting of a decrease in the number of venous drainage routes. There was a trend for the posterior route to close before the anterior drainage or cortical drainage route. This suggests the occurrence of a staged progression in a regular direction in cavernous sinus dAVFs. Without treatment aiming at a complete cure, most cavernous sinus dAVFs can behave benignly, with a low possibility of development of cortical venous reflux during follow-up.