Anti-HU Antibodies Associated Focal Epileptogenic Encephalitis Successfully Treated with Rituximab: A New Limited form of Chronic Focal Encephalitis of the Rasmussen’s Type?

A young girl was diagnosed having non-paraneoplastic focal epileptogenic encephalitis after the development of recurrent non-convulsive status epilepticus. Diagnostic work-up revealed a focal lesion on the mesial face of the frontal lobe, the presence of oligoclonal bands in the cerebrospinal fluid and the presence of anti-HU antibodies in serum. Complete researches for occult neoplasm resulted negative for up to 5 years. Due to the autoimmune pathogenesis supposed, the patient has been treated with B-cell depletion using the monoclonal antibody rituximab. No further status epilepticus has been seen observed while anti-HU antibodies titre decreased during the follow-up. After 7 years of follow-up the patient is stable with rare focal motor seizures, well controlled by antiepileptic drugs. The case represents a possibly limited variant of chronic focal encephalitis in which we hypothesized a pathogenic role of anti-neuronal antibodies, namely anti-HU antibodies: non-convulsive refractory status epilepticus has been described in anti-HU associated paraneoplastic disorders and antineuronal antibodies can be present in non-paraneoplastic systemic autoimmune disorders. Our case showed a very good response to B-cell depletion using rituximab, without any adverse event, indicating that the use of this therapeutic may represent a good choice in the treatment of atypical refractory epilepsy in which an autoimmune pathogenesis can be supported by the laboratory findings. We suggest the diagnosis of limited chronic focal encephalitis: we suggest the research of anti-neuronal antibodies in every case of unsolved epileptogenic encephalitis, in particular those occurring with non-convulsive status epilepticus, and the use of immunosuppressive/immunomodulatory treatment in such cases.