Superficial siderosis as seen on a brain MRI represent tiny amount of very superficial bleeding over the brain cortex or within the sulci (shallow grooves that separate infoldings of cortex called gyri). Superficial siderosis can present as a rare stand alone disease when it causes hearing loss, weakness, balance problems, dementia, in which case the source of bleeding can be potentially found and treated.
Most commonly, superficial siderosis is a marker of a small vessel disease of older adults called cerebral amyloid angiopathy (CAA). Although much less common than microbleeds, it is an important marker of high brain bleeding risk when found on brain MRI of CAA patients. The presence/absence and extent of superficial siderosis can help physicians understand approximate yearly bleeding risk in CAA, guiding decision making when blood thinners are needed. There is currently no specific treatment for CAA-related superficial siderosis. Similar to microbleeds, the aim is to prevent symptomatic potentially fatal brain bleeds.
The other interesting fact about superficial siderosis is that it might cause transient neurologic symptoms, clinically almost similar to what is called a transient ischemic attack (TIA). Such attacks might include one-sided weakness, coordination or sensory symptoms, vision, speech or gait disturbances. The management of these two conditions are totally different as TIA patients typically need blood thinners whereas these medications might increase the risk of brain bleeding in patients with superficial siderosis.
Overall, it is important to obtain and carefully review the MRI sequences that show chronic blood products (called GRE or SWI) in every patient who undergo MRI study. If superficial siderosis or microbleeds are found, referral to an expert can improve management by decreasing bleeding risks.