Anti-MOG and Anti-AQP4 Positive Neuromyelitis Optica Spectrum Disorder in a Patient with Myasthenia Gravis (273)

Objective: Neuromyelitis Optica Spectrum Disorder (NMOSD) with anti-aquaporin 4 antibodies (anti-AQP4) can occur in the setting of existing myasthenia gravis (MG) especially following thymectomy. However, no cases of NMOSD with myelin oligodendrocyte glycoprotein antibodies (anti-MOG) with comorbid MG have been described. We present a case report of a patient with anti-AQP4 and anti-MOG positive NMOSD in the setting of MG. Background: NA Design/Methods: A 54-year-old female with history of MG experienced right sided weakness that progressively worsened over 24 hours preceded by a sharp right-sided headache radiating to her neck. Physical exam was notable for 4/5 strength in her right arm and leg and hyperreflexia of the right upper extremity. The patient was diagnosed with MG more than 15 years prior to this presentation, and she underwent thymectomy 5 years prior. Her MG had been well-controlled on pyridostigmine. MRI of the cervical and thoracic spine revealed diffuse, longitudinally extensive edema beginning at the level of T1–T2 and extending up into the obex and area postrema with associated contrast enhancement of levels C1–C4. These findings raised suspicion of NMOSD, and she was treated with IV methylprednisolone 1g daily for 5 days with improvement of strength nearly to baseline. Serum AQP4 and anti-MOG antibodies were positive with no oligoclonal bands in the CSF. This confirmed the diagnosis of NMOSD. Given the extent of her initial lesion and the high risk of relapse with AQP4-positive NMOSD, treatment with eculizumab was initiated. Results: NA Conclusions: We present a case of the co-occurrence of two autoimmune channelopathies, MG and NMOSD. The occurrence of anti-MOG positive NMOSD with other coexisting autoimmune disease is thought to be rare. To our knowledge this is the first case report with positive anti-AQP4 and anti-MOG antibodies in a known case of MG. Disclosure: Dr. Bates has nothing to disclose. Dr. Chisholm has nothing to disclose. Dr. Miller has nothing to disclose. Dr. Guduru has nothing to disclose.