To correlate MRI brain lesions with clinical outcomes in pediatric anti-NMDA receptor encephalitis (pNMDARE).

Up to 50% of MRIs in NMDARE are reportedly abnormal. However, data is limited on range and types of abnormalities, and also how abnormal MRIs associate with outcomes in pNMDARE.

This was a multi-center retrospective cohort study with ten institutions. NMDARE was defined as positive CSF NMDA-receptor antibody and at least one neuropsychiatric symptom. Patients with prior HSV encephalitis were excluded. Outcomes were assessed by the modified Rankin Score (mRS) at 1 year with good (mRS ≤ 2) and poor (mRS ≥ 3) outcomes and also for full recovery (mRS=0) versus incomplete recovery (mRS>0). Statistical analyses were performed using SAS 16.0 (Cary, NC). 

A total of 169 patients with pNMDARE were included, with one-year mRS available in 134/169 (79%). Abnormal MRIs were found in 59/169 (35%), and were associated with an increased likelihood of intubation and ICU admission (chi-square, p = 0.038 and p=0.045, respectively). The most common T2 FLAIR lesion locations were frontal (29/59, 49%), temporal (28/59, 47%), parietal (19/59, 32%), and hippocampal lesions (11/59, 19%). MRI enhancement was seen in 34/165 (21%) and MRI brain atrophy was seen in 4% (6/168). MRI features that predicted incomplete recovery at one year (mRS > 0) was the presence of T2 frontal lobe lesions (chi-square, p = 0.0427). G-tube placement and intubation also predicted incomplete recovery. On multivariable logistic regression analysis using backward selection, one-year mRS was associated with: intubation (OR 0.232, 95%CI 0.103-0.526) and T2 frontal lesions on MRI (OR 0.373, 95% 0.148-0.938).

Abnormal frontal lesions on MRI along with intubation may associate with one-year mRS in pNMDARE. MRIs may be a helpful tool for prognostication, which will be examined in future studies.