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

To evaluate the clinical features and outcomes of paediatric probable antibody-negative autoimmune encephalitis.

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.

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).

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.