Investigation of anti-neuronal antibodies in status epilepticus of unknown etiology: a prospective study.

There have been recent reports of antibody-mediated status epilepticus. The objective of our study was to investigate the prevalence of neuronal autoantibodies in patients with status epilepticus (SE) with unresolved etiology. The presence of neuronal autoantibodies was investigated prospectively in adult patients with SE who presented to our clinic between February 2012 and December 2013 with unresolved etiology. Clinical and electrophysiologic features of seropositive patients were recorded. Also, seronegative and seropositive patient groups were compared in terms of demographic and clinical features, treatment responses, and outcomes. Neuronal antibodies against N-methyl-D-aspartate receptor (NMDA-R) were positive in 2 patients, against glycine receptor (Gly-R) in 2 patients, and against gamma-aminobutyric acid-A receptor [GABA(A)R] in 1 patient, which constituted a total of 5 (22.7%) of 22 patients with SE with unidentified etiology. One of three patients with systemic tumors was positive for GABA(A)R antibody. Four patients had a short epilepsy duration, while one of the NMDA-R antibody-positive patients had chronic epilepsy and double cortex finding in MRI. There was no significant difference between seropositive and seronegative patient groups in terms of demographic and clinical features, treatment responses, and outcomes. Neuronal antibodies are found in a sizeable portion of de novo SE patients, who are potential candidates of autoimmune encephalitis. Alternatively, these antibodies may presumably also emerge in SE patients with a chronic epilepsy history as an epiphenomenon. Further research is required to make the distinction between these two different antibody formation mechanisms.