To investigate the prognostic role of neutrophil to lymphocyte ratio (NLR) in autoimmune encephalitis (AE) in children and adults.

AE involves immune-mediated inflammation of the brain resulting in a variety of neuropsychiatric manifestations in children and adults.
One potential AE prognostic marker is the NLR. NLR can predict outcomes in other diseases, including sepsis, and its predictive ability has been reported in AE. Here we perform a systematic review on the role of NLR in AE.

Keywords – “neutrophil to lymphocyte ratio in encephalitis” and “neutrophil to lymphocyte ratio in autoimmune encephalitis” – were searched in PubMed and EBSCO on April 24, 2024. Inclusion criteria was: (1) English peer-reviewed articles and (2) evaluation of NLR in autoimmune encephalitis in humans. Two independent searches were performed (N.K. and G.G.).

Initial keyword search yielded 122 results, with 106 studies excluded. A total of 16 studies were included (two pediatric and 14 adult). Five studies were exclusively in NMDARE (one pediatric, four adult). Eight investigated definite (antibody-positive) AE and three included probable (antibody-negative) AE (one pediatric, two adult). Mean NLR cutoff was 4.48.

In children, the NLR was associated with intubation and rehabilitation length of stay in NMDARE and disease severity in definite and probable AE.

Of the eight definite AE adult studies, high NLR was associated with disease severity (2), ICU admission (1), poor neurological outcomes (3) and first-line treatment failure (2).

In the two probable AE adult studies, high NLR was associated with first-line treatment failure (1) and poor neurological outcomes (1).

In the four adult NMDARE studies, high NLR was associated with first-line treatment failure (1), disease severity (2), and poor neurological outcomes in patients requiring mechanical ventilation (1).

Limitations include publication bias.

NLR may be a prognostic marker for AE in children and adults.