Treatment of Susac Syndrome

Susac syndrome is a microangiopathy of the brain, retina, and cochlea. Several lines of evidence support the concept that this disease is an acquired autoimmune disorder. Prospective, randomized, controlled studies of treatments are not available because the disease is rare. Furthermore, the average period of follow-up in reported cases is short, limiting a complete understanding of the natural history of the disease. Empirical treatment strategies are therefore based upon expert recommendations and anecdotal reports of response to various immunomodulators, and the appropriate duration of therapy is not known. In our opinion, the encephalopathic form of Susac syndrome should be treated early and aggressively to avoid cognitive dysfunction and disability. Induction therapy with pulse methylprednisolone frequently proves to be inadequate. Additional agents, including intravenous immunoglobulins, intravenous cyclophosphamide, or rituximab are often necessary to induce a sustained remission. Maintenance therapy with oral glucocorticoids combined with intravenous immunoglobulins, mycophenolate mofetil, methotrexate, azathioprine, cyclophosphamide, or rituximab is typically necessary to achieve a sustained remission. Aspirin may be used as an adjunctive agent, although evidence showing efficacy is scant. The response to treatment should be closely monitored by frequent clinical examinations, brain MRI, and fluorescein angiography. Once disease remission has been established, it appears prudent to continue maintenance treatment for at least two additional years, although the real long-term risk of future relapses remains unknown. Establishing a multicenter patient registry and biorepository is essential to study the pathogenesis of the disease, further define the duration of disease, identify reliable biomarkers that aid early diagnosis and assess risk of relapse, and develop effective disease-specific therapies.