EVOLUTION OF AUTOIMMUNE RETINOPATHY IN STIFF PERSON SYNDROME: A CASE REPORT.

Purpose: The aim of this study was to report a case of autoimmune retinopathy as the presenting feature of stiff person syndrome and assess its evolution.

Methods: Case report.

Results: A 35-year-old man presented with progressive, chronic vision loss. On initial examination, visual acuity measured 20/20 in the right eye and 20/50 left eye. Humphrey Visual Field testing demonstrated decreased foveal threshold in both eyes. Mild subfoveal ellipsoid zone loss was noted on optical coherence tomography. Five years later, the patient presented with painful lower extremity muscle spasms and stiffness and complained of increasing vision loss with difficulty distinguishing colors. Optical coherence tomography showed marked progression of ellipsoid zone loss. Scotoma was demonstrated on Humphrey visual field, and electroretinography demonstrated reduced responses consistent with bilateral severe maculopathy. Serum testing showed autoantibodies to the glutamic acid decarboxylase 65-kDa isoform (GAD65) at a high titer and a diagnosis of autoimmune retinopathy in the setting of stiff person syndrome was made. A systemic workup for malignancy was negative. The patient was treated with IV immune globulin and transitioned to rituximab with improvement in systemic symptoms.

Conclusion: Unlike previous cases of autoimmune retinopathy in the setting of stiff person syndrome, vision symptoms and optical coherence tomography 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.