Clinical features and outcomes of paediatric probable antibody‐negative autoimmune encephalitis

Abstract Aim To evaluate the clinical features and outcomes of paediatric probable antibody‐negative autoimmune encephalitis. Method This retrospective cohort study included 66 patients (43 males and 23 females) with probable antibody‐negative autoimmune encephalitis. Clinical outcomes were assessed using the modified Rankin Scale (mRS) and the Clinical Assessment Scale in Autoimmune Encephalitis (CASE). A good 1‐year clinical outcome was defined as an mRS score of 0 to 2 and a CASE score of 0 to 4. Seizure outcomes at 1 year were evaluated separately. Results Median age at onset was 10 years (interquartile range [IQR] 5 years 4 months–12 years) and the median follow‐up was 24 months (IQR = 12.5–49.8). Common neurological symptoms included altered mentality (92.4%) and seizures (84.8%). Most patients (89.4%) received first‐line immunotherapy (methylprednisolone or intravenous immunoglobulins), while 33.3% received second‐line immunotherapy (rituximab with or without tocilizumab). At 1 year, 95.1% (58 of 61) achieved good clinical outcomes according to the mRS and 91.8% (56 of 61) according to CASE. However, 44.2% had persistent seizures, 32.8% had cognitive problems, and 27.9% had behavioural problems. Neither immunotherapy timing nor second‐line immunotherapy affected outcomes. Status epilepticus was the only risk factor for persistent seizures at 1 year (odds ratio = 4.16; 95% confidence interval = 1.16–14.92). Interpretation Although most children with antibody‐negative autoimmune encephalitis showed favourable clinical outcomes after immunotherapy, persistent seizures and cognitive and behavioural deficits remained. Absence of status epilepticus predicted better seizure outcomes.