Intracranial dural arteriovenous fistulas (DAVFs) are abnormal arteriovenous shunts developing on the dura mater, usually within the wall of a dural sinus, which can be asymptomatic for years. ¹ , ² , ³ , ⁴ , ⁵ , ⁶ , ⁷ , ⁸ , ⁹ Majority of DAVFs are idiopathic and solitary. ¹ , ⁵ Intracranial DAVFs are fairly common, accounting for 10-15% of all intracranial arteriovenous shunts, ⁶ whereas multiple DAVFs at separate sites are relatively rare, accounting for 7% of all intracranial DAVFs. ¹⁰ , ¹¹ , ¹² , ¹³ Patients with multiple DAVFs usually present with life-threatening hemorrhages related to venous outflow obstruction or acute dysfunction. The exact mechanism of occurrence and natural history remain undetermined, but various factors, such as congenital development, venous hypertension, head trauma, venous thrombosis, and radiation therapy, may be involved. ⁷ , ¹⁰ , ¹⁴

Multiple DAVFs, although rare, do exist and it is important to look for any evidence of their presence when evaluating patients with symptoms suggestive of arteriovenous fistulas. In this study, we present a case of multiple DAVFs. We have focused on this unique type of venous drainage in dural arteriovenous fistulas.

A fifty year old man with history of long term headache and sudden onset of decreased level of consciousness was admitted to Namazee Hospital, affiliated to Shiraz University of Medical Sciences, Shiraz, Iran, in 2011. Brain computed tomography (CT) showed right parietal intraparenchymal hemorrhage Figure 1. The patient had glasgow coma scale (GCS) 12 on arrival. Figure 1

Brain computed tomography showing right parietal intraparenchymal hemorrhage

Intracranial DAVFs with retrograde cortical venous drainage are aggressive lesions presented by intracranial hemorrhage, intracranial hypertension, seizures, progressive neurological deficits, and dementia. Prompt treatment is necessary because the natural history of untreated lesions is associated with a poor prognosis. ¹ , ³ , ⁴ , ⁵

Intracranial DAVFs can be classified according to the type of venous drainage. Borden, et al. ¹⁵ proposed a classification of DAVFs, grouped into three types based upon their venous drainage including type I with drainage to a dural sinus, type II with drainage to a dural sinus and reflux into cortical veins, and type III only with drainage to the cortical veins. Aggressive clinical presentation correlates strongly with Borden types: 2% of type I, 40% of type II, and 80% of type III. ⁵ , ¹⁵

DAVFs are presented with intracranial hemorrhage or neurological deficits. However, source of bleeding was controlled easily in our study. Treatment of DAVFs with cortical venous drainage is aimed in occlusion of the venous drainage or all arterial supply that can be surgical, endovascular, or a combination of both. ² , ³ , ⁴ , ¹⁶

Most DAVFs are idiopathic and solitary. ¹ , ⁵ The term multiple DAVF has two different meanings in literature. Some authors use the term to indicate DAVFs that developed simultaneously at different sinuses, whereas the others use it to indicate a second DAVF that developed at other sinuses at the interval after resolution of initial DAVF. ⁵ The presence of two or more different DAVFs draining into one single sinus has not been described. In this case, both DAVFs simultaneously drained into the SSS in our patient. Both DAVFs were connected to two abnormal giant vascular pockets that developed intraparenchymal hemorrhage and were different to a simple DAVF or the multiple DAVFs described elsewhere.

Based on the findings within this case, we suggest that the definition and classification of DAVFs be revised, and a new category including separate lesions draining into a common venous drainage be considered. Such a classification scheme of course needs report and collection of further cases into a comprehensive case series.

Planning of treatment strategies for multiple DAVFs requires careful analysis of the venous drainage from the affected sinuses and cerebral hemodynamics. We presented a unique type of multiple DAVFs draining into a common venous drainage SSS instead of the routinely reported separate drainage. The introduction of this new case opens a new concept, which may be useful for further classification or suggestion of the responsible pathophysiologic processes.