Evolution of Autoimmune Retinopathy in Stiff Person Syndrome: A Case Report.

PURPOSE:To report a case of autoimmune retinopathy (AIR) as the presenting feature of Stiff Person Syndrome (SPS) and assess its evolution. OBSERVATIONS:A 35-year-old man presented with progressive, chronic, vision loss. On initial examination, visual acuity measured 20/20 OD and 20/50 OS. Humphrey Visual Field testing (HVF) demonstrated decreased foveal threshold OU. Mild subfoveal ellipsoid zone loss was noted on Optical Coherence Tomography (OCT). Five years later the patient presented with painful lower extremity muscle spasms and stiffness and complained of increasing vision loss with difficulty distinguishing colors. OCT showed marked progression of ellipsoid zone loss. Scotoma were demonstrated on HVF and electroretinography demonstrated reduced responses consistent with bilateral severe maculopathy. Serum testing showed autoantibodies to the glutamic acid decarboxylase 65-kilodalton isoform (GAD65) at a high titer and a diagnosis of AIR in the setting of SPS was made. A systemic workup for malignancy was negative. The patient was treated with IVIG and transitioned to rituximab with improvement in systemic symptoms. CONCLUSIONS:and Importance: Unlike previous cases of AIR in the setting of SPS, vision symptoms and OCT changes presented years before the onset of muscle spasms. Etiologies such as SPS should be on the differential of unexplained retinopathy, even in the absence of systemic symptoms, especially when paraneoplastic etiologies are ruled out.