Treatment Of Anti-Dppx-Encephalitis Refractory To Corticosteroids, Plasma Exchange And Rituximab

Objective: To describe a case of anti-DPPX encephalitis refractory to steroids, plasma exchange and rituximab.Background:Anti-DPPX encephalitis is an autoimmune encephalitis which presents with progressive encephalopathy, rigidity, and myoclonus as well as autonomic instability, GI dysmotility, and progressive weight loss. Successful treatment of anti-DPPX encephalitis with intravenous steroids, plasma exchange and rituximab has been previously described.Methods: Report of a case.Results: A 41yo obese man presented with 1 year of depression, 150lb weight loss, progressive short-term memory loss, diffuse myoclonus with hyperekplexia, truncal ataxia, appendicular rigidity, periodic limb movements in sleep, supraventricular tachycardia, and diaphoresis. Evaluation for malignancy and infectious etiologies were negative. A CSF autoimmune encephalitis panel was positive for anti-DPPX antibodies. He had been previously treated with 1g IV methylprednisolone with clinical worsening. He was then treated with a cycle of plasma exchange with mild improvement in myoclonus and short-term memory. However, his weight loss, truncal ataxia, and dysautonomia persisted. He was then treated with 2 doses of rituximab. Within a month he had clinical deterioration with further weight loss and progression of his short-term memory loss, hyperekplexia, and dysautonomia. A second cycle of plasma exchange was completed resulting in some temporary beneficial effects, but no dramatic improvement. Two weeks later, he was noted to have continued weight loss and persistent symptoms. A percutaneous gastric tube was placed for initiation of tube feeds. He was then started on cyclophosphamide 750mg/m2 with concomitant IV immunoglobulin 1g/kg monthly infusions. Following the 3rd treatment cycle his appetite increased with resultant 10lbs weight gain and had improvement in short-term memory, depression, myoclonus, appendicular rigidity, and autonomic instability.Conclusions: Anti-DPPX encephalitis can be refractory to many first line immunotherapies. Rapid escalation or changes in therapies is warranted in the setting of continued progressive symptoms including weight loss. Disclosure: Dr. Smith has nothing to disclose. Dr. Goodman has received personal compensation for activities with Acorda Therapeutics, Biogen Idec, EMD-Serono, Genzyme-Sanofi, GW Pharma, Novartis, Purdue, and Teva Neuroscience. Dr. McKeon has received research support from Medimmune. Dr. Samkoff has nothing to disclose.