Macular edema after siponimod treatment for multiple sclerosis: a case report and literature review

BACKGROUND: As a modulator of the sphingosine 1-phosphate receptor, siponimod is administered as a therapeutic intervention for multiple sclerosis. A previous phase 3 study first reported siponimod-associated macular edema. Since that report, there were only few relevant reports in clinical settings. Here, we report a case of secondary progressive multiple sclerosis developed macular edema after siponimod treatment. We also review the progress of sphingosine 1-phosphate receptor modulators, elaborate on accepted mechanisms in treating multiple sclerosis, and discuss the causation of siponimod-associated macular edema. CASE PRESENTATION: A 38-year-old Chinese female patient with secondary progressive multiple sclerosis, who had recurrent numbness of the limbs and right leg fatigue, developed mild macular edema following 4 months of siponimod treatment. The macular edema resolved after discontinuing the medication, and did not recur after resuming siponimod. CONCLUSION: Although siponimod-associated macular edema may be rare, mild, transitory, and manageable, it cannot be ignored and requires ongoing vigilance.