Abstracts

Rationale: Neuronal autoantibodies targeting intracellular or extracellular components have been increasingly recognized as a cause of encephalitis. However, due to scarcity and complexity of the disease, extensive clinical and epidemiologic studies are lacking. We conducted multicenter nationwide registry of patient with possible autoimmune encephalitis. From this registry, we aim to evaluate the prevalence of such antibodies, their clinical differences, and underlying neoplasms.Methods: Between Jan 2013, and Dec 2014, from 67 hospitals across Korea, 1698 patients with symptoms of possible autoimmune encephalitis (acute or subacute onset cognitive impairment, psychiatric symptom or seizure) were screened for neuronal antibodies. The antibodies, includes neuronal surface (NMDAR, LGI1, CASPR2, AMPA1, AMPA2, and GABAB-R) and onconeuronal (anti-Hu, -Yo, -Ri, -Ma2, -CV2/CRMP5, and -amphiphysin) antibodies. Demographics and clinical information of the patient and result of diagnostic tests were obtained from questionnaires filled out by study investigators or the referring physicians.Results: Total 105 (6.18%) patients tested positive for neuronal autoantibodies. Median age was 40, and 56 (51.4%) were male. Neuronal surface antibody was detected in 88 (82.2%), and most common antibody type was anti-NMDAR (n=57, 53.3%). Onconeuronal antibody was detected in 21 (19.6%) of the patients, and the most common type was Ma2/Ta (n=9, 8.4%). The Antibody types varied with age (p<0.0001). All patients under 18 and three quarter of patients between age 18-44 had anti-NMDAR antibody. However, majority of patients over age 45 had either other neuronal surface antibody or onconeuronal antibody. Underlying neoplasm was screened in 68 (63.5%) and was detected in 17 (25.0%). Presenting symptoms also varied according to antibody types. More patients with anti-NMDAR encephalitis complained psychiatric symptom, however cognitive impairment was common in patients with other neuronal surface antibodies. Temporal lesions on MRI was more frequently observed in patients with other neuronal surface antibodies, and NMDAR encephalitis patients had more pleocytosis in CSF study.Conclusions: From nationwide registry of patients with symptoms of suspected autoimmune encephalitis, we detected neuronal antibodies in 6.18% of the patients. Neuronal surface antibody was more commonly detected than onconeuronal antibodies. This study results confirm that autoimmune encephalitis differ in demographics, clinical characteristics according to autoantibodies.