Rare antibody-mediated and seronegative autoimmune encephalitis: An update

Paralleling advances with respect to more common antibody-mediated encephalitides, such as anti-N-methyl-D-aspartate receptor (NMDAR) and anti-leucine-rich glioma-inactivated 1 (LGI1) Ab-mediated encephalitis, the discovery and characterisation of novel antibody-mediated encephalitides accelerated over the past decade, adding further depth etiologically to the spectrum of antibody-mediated encephalitis. Herein, we review the major mechanistic, clinical features and management considerations with respect to anti-γ-aminobutyric acid B (GABAB)-, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropinoic receptor- (AMPAR), anti-GABAA-, anti-dipeptidyl-peptidase-like protein-6 (DPPX) Ab-mediated encephalitides, delineate rarer subtypes and summarise findings to date regarding seronegative autoimmune encephalitis. •GABAB encephalitis commonly involves a limbic encephalitis with refractory seizures.•GABAB and AMPAR encephalitis associate with tumours in over 50% of cases respectively.•GABAA encephalitis is rare, but MRI findings are unique relative to other forms of AIE.•DPPX encephalitis causes prodromal and neuropsychiatric features and CNS hyperexcitability.•Seronegative encephalitis represents a heterogenous group warranting further study.