D-032 | Refractory epilepsy in limbic encephalitis due to anti-GAD, possibly linked to the persistence of high levels of anti-GAD antibodies and neuronal loss in the medial temporal lobe.

Cognition, Behavior, and Memory
Author: María Gabriela Avalos Navas | Email: dramariagabriela@outlook.es

María Gabriela Avalos Navas^1°, Carlos Alberto Mangone^1°, Marcelo Esteban Katz^1°

^1° Servicio de Neurología, Hospital D. F. Santojanni, CABA

Limbic encephalitis (LE) is characterized by cognitive symptoms and epilepsy, which are related to medial temporal lobe disfunction. Its etiology has been associated to paraneoplastic syndrome, infections, and autoimmune diseases. Among these, LE related to anti-glutamic acid decarboxylase antibodies (anti-GAD) deserves special attention, as seizures tend to be refractory, with no clear mechanism. Here, we describe the case of a 33-year-old woman with no pathological history, who developed a LE Ssyndrome alongside type I diabetes. Screening for neoplasms, infections, and systemic autoimmune diseases was negative. Blood and cerebrospinal fluid analyses were negative for NMDA, AMPA1/2, CASPR2, LGI1, DPPX, GABAb, and CKVD autoantibodies, but positive for anti-GAD in both fluids. After resolving the acute phase, the patient received chronic immunosuppressive and antiepileptic treatment, but continued to experience daily focal seizures as a sequela. After 8 years, symptoms worsened again (cognitive decline and an increase in the number of seizures per day). Tests showed persistence of high titers of anti-GAD, as well as decreased metabolic activity in the medial temporal lobe. We discuss the clinical case and review the literature on CNS damage mediated by the immune system.