Anti-NMDA receptor encephalitis and brain atrophy in children and adults: A quantitative study

To determine whether brain atrophy was present in patients with anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE) using qualitative and quantitative analyses of brain magnetic resonance imaging (MRI) and to explore clinical differences in patients with anti-NMDARE with or without brain atrophy.

A retrospective observational study encompassing the serologic, cerebrospinal fluid, and brain MRI data of 23 patients with anti-NMDARE was conducted. Median patient age was 14 years (interquartile range [IQR], 12 years). The cohort included 15 children (<18 years old) and 8 adults (≥18 years old). There were 6 male and 17 female patients. Imaging analysis involved 2 expert readers' observations of MRIs and automated volumetric quantification using NeuroQuant (CorTechs Labs, Inc.) software.

Of 23 pediatric and adult patients, 11 patients had 14 brain MRIs that were quantitatively analyzed. Quantitative NeuroQuant volumetric analysis showed atrophy in 9 of 14 MRIs for 7 of 11 patients compared to age-controlled normative data. In these 9 MRIs, atrophy was present in the temporal lobes (n = 9), cerebral cortex (n = 3), and cerebellum (n = 3). Qualitative analysis of 59 MRIs (23 patients) revealed volume loss in 6 patients: 5 with global cerebral and temporal lobe volume loss and 1 with temporal lobe volume loss. No patient showed cerebellar volume loss on qualitative analysis. Mean length of stay in the intensive care unit was not significantly different for patients with or without quantitative volume loss (3.5 [5.2] vs 27.4 [23.4] days; p = 0.08).

In this cohort of patients with anti-NMDARE, quantitative volumetric analysis showed brain atrophy, particularly affecting the temporal lobes, in 64% (7/11) of the patients. Qualitative analysis showed brain atrophy in 26% (6/23). These findings highlight the increased sensitivity of quantitative methods for volume loss detection. Larger studies are needed.