Introduction: Superficial siderosis is the occult deposition of hemosiderin within the cerebral cortex due to repeat microhemorrhages within the central nervous system. The collection of hemosiderin within the pia and superficial cortical surface can lead to injury to the nervous tissue. The most common presentation is occult sensorineural hearing loss, although many patients have been misdiagnosed with diseases such as multiple sclerosis and amyotrophic lateral sclerosis before being diagnosed with superficial siderosis. Only one case report exists in the literature describing an intracranial dural arteriovenous fistula as the putative cause for superficial siderosis.

Methods: We describe two cases of superficial siderosis caused by a dAVF. Both patients had a supratentorial, cortical lesion supplied by the middle meningeal artery with venous drainage into the superior saggital sinus. In both patients, symptoms improved dramatically after endovascular embolization.

Results: The similar anatomic relationship of both dAVFs reported presents an interesting question about the pathogenesis of SS. Similar to the pathologic changes seen in the formation of intracranial arterial aneurysms, it would be possible that changes in the blood vessel lining and wall might predispose a patient to chronic, microhemorrhage resulting in local superficial siderosis.

Conclusions: We describe the second and third cases of a dAVF as the cause of SS, and the first cases of successful treatment of SS-associated dAVF with endovascular embolization. As non-invasive imaging techniques become more sensitive and easily obtained, one must consider occult intracranial vascular malformations such as dAVF as a possible etiology for SS. A logical next step could be a prospective imaging trial to identify the incidence of SS within an at-risk population. Additionally, post mortem analysis of the vascular and neural tissue of these and similar patients may help to identify any anatomic pathological changes that would result in SS.

Patient Care: Empower practitioners to utilize both non-invasive and invasive imaging techniques to diagnosis and treat superficial siderosis caused by a dural arteriovenous fistula

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the clinical and imaging hallmarks of intracranial superficial siderosis 2) Understand the pathologic mechanism of superficial siderosis caused by intracranial vascular malformations, specifically dural arteriovenous fistulas 3) Include superficial siderosis caused by a dural arteriovenous fistula in a differential diagnosis for a patient with unexplained neurologic deficit in the appropriate patient demographic

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