Aims NMDAR-antibody encephalitis presents in adults and children with neuropsychiatric features, seizures, movement disorders and autonomic instability. This BPNSU study aimed to report the clinical features, management and neurological outcomes of UK paediatric patients.
Methods An initial and follow-up questionnaire was sent out to physicians following voluntary reporting of confirmed cases of NMDAR-antibody encephalitis through the BPNSU. Out of 35 cases notified, 31 met the case definition.
Results The majority of patients were female (23/31; 74%; age range 22 months to 17 years) most presenting in pre-school and teenage years. Male patients only presented from school age (age range 6 to 17 years), which was significantly different to the female presentation age range (p = 0.03). 55% of the patients were Caucasian. The most common presenting symptoms were neuropsychiatric (28/31), behavioural change (27/31), and seizures (21/31). Movement disorder was present in 67% of patients (21/31); in 3 patients this was the only symptom. Atypical or monosymptomatic presentations (e.g. neuropsychiatric features only) occurred in 7 patients. EEG was the most frequently abnormal investigation (28/21; 93%). An ovarian teratoma was found in one patient. First-line immunotherapy was used in all cases. The most commonly used 2nd line agents were cyclophosphamide (3), rituximab (3) or both (3). Most patients showed a response to immunotherapy within 30 days. Thirteen patients required ICU admission (13/31; 42%). The average in-patient stay was 80 days (range 10 – 365 days). Patients required, on average, the involvement of 4 additional health professionals to the admitting team. Only 1 patient in the retrospectively diagnosed group (n = 7) made a full eventual recovery, compared to 78% (18/23) of the prospective group (p = 0.003). 7 patients suffered a relapse; 3 of these had an atypical presentation, making relapse more common in this group (3/7; 43%) compared to the patients with a more typical presentation (4/19; 21%).
Conclusions In the UK, paediatric NMDAR-antibody encephalitis presents mainly in females with neuropsychiatric features, behavioural change and seizures, usually supported by an abnormal EEG. Tumours are uncommon. Monosymptomatic presentations exist and frequently relapse. Patients do better if diagnosed at the time of presentation. Prolonged hospital admission is common and requires a multi-disciplinary approach.