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Background The aim of the current study was to explore the characteristics of cerebrospinal fluid (CSF) cytology in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis.Methods CSF was collected from patients with anti-NMDAR encephalitis at Peking Union Medical College Hospital and Henan Provincial People’s Hospital from 01 January 2015 to 31 December 2018, and cytological characteristics and other parameters of the CSF were analyzed.Results CSF cytological data were obtained from 164 patients with anti-NMDAR encephalitis. Visible signs of inflammation were identified in cytological analyses of 112 patients’ CSF, including 46 cases of mild inflammation, 58 of moderate inflammation, and 8 of severe inflammation. With regard to inflammation type, 89 cases were classified as lymphocytic inflammation, 22 as mixed inflammation with both lymphocytes and neutrophils, and 1 case was classified as mixed inflammation with lymphocytes, neutrophils, and eosinophils. Activated lymphocytes were detected in 51 patients, and plasma cells were detected in 16. Oligoclonal bands were detected in 111/164 patients, and 51 patients were positive for specific oligoclonal bands in CSF. The positivity rate was 45.9%. In comparison with routine CSF examination with an inflammation positivity threshold of > 5 × 10 6 cells/L, the inflammation positivity rate of CSF cytology was significantly higher (68.3% versus 64.0%, p < 0.001).Conclusions The comparatively higher inflammation positivity rate and the superiority of evaluating cell morphology render CSF cytology an effective tool for identifying anti-NMDAR encephalitis and investigating its pathogenesis.

Background Encephalitis associated with antibodies against alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is an extremely rare type of antibody-mediated encephalitis. This research aims to investigate the clinical characteristics and prognosis of anti-AMPAR encephalitis. Methods This retrospective study enrolled nine patients with anti-AMPAR encephalitis. Demographic information, clinical manifestations, laboratory and radiological findings, treatment and response were collected and analyzed. These patients were followed up with an average period of 72 weeks to gather prognostic information. Results Nine patients (7 females and 2 males) were enrolled with the mean age of disease onset as 59 years old. Three clinical syndromes, including limbic encephalitis (n=7; 78%), pure amnesia (n=1; 11%) and fulminant encephalitis (n=1; 11%) were identified. New symptoms of dysphagia and deafness were identified in the clinical spectrum of anti-AMPAR encephalitis. All patients had positive blood AMPAR antibodies, and six of them (67%) had paired positive antibodies in cerebrospinal fluid (CSF). Brain magnetic resonance imaging (MRI) were abnormal in 75% of the patients with no specific patterns recognized. Six patients (67%) had tumors, including lung cancers or thymomas. After immunotherapy and oncotherapy, partial improvement of neurological symptoms was observed among all 6 patients with available records during their hospitalization. During a mean follow-up of 72 weeks, 3 patients had marked improvement of modified Rankin Scale (mRS), one patient had unchanged mRS, 4 patients died and the other one was lost. Conclusions Anti-AMPAR encephalitis mainly presents as limbic encephalitis. Anti-AMPAR encephalitis is paraneoplastic in 67% cases and intensive screening for tumors is recommended for all anti-AMPAR patients. Although patients showed a good short-term therapeutic response, the overall prognosis was not satisfactory.