Fulminant Anti-GAD antibody encephalitis presenting with status epilepticus requiring aggressive immunosuppression

Antibodies against glutamic acid decarboxylase (GAD) are reported in association with numerous neurological conditions including temporal lobe epilepsy and limbic encephalitis. We report a case of Anti-GAD-Antibody associated encephalitis presenting with epilepsia partialis continua (EPC) progressing to a fulminant encephalopathy preferentially affecting the frontal lobes associated with coma and refractory status epilepticus. The abnormalities identified on MRI included marked bilateral frontal lobe involvement which has not been reported in other auto-immune encephalitides and may be specific for Anti-GAD-Antibody associated encephalitis. Similar to the majority of cases of Anti-GAD associated neurological disturbance no underlying malignancy was identified. Treatment with high dose corticosteriods, IVIG and plasmapheresis had minimal response, but escalation of treatment with rituximab and cyclophosphamide was associated with clinical improvement, reducing antibody titers and resolution of MRI changes.