Flortaucipir (tau) PET in LGI1 antibody encephalitis

The contributors to persistent cognitive impairment and hippocampal atrophy in leucine‐rich glioma‐inactivated 1 antibody encephalitis (LGI1) patients are unknown. We evaluated whether tau neuropathology measured with [(18)F]flortaucipir PET neuroimaging associated with persistent cognitive impairment and hippocampal atrophy in four recovering LGI1 patients (3 men; median age, 67 [37–88] years). Imaging findings in cases were compared with those observed in age‐ and gender‐similar cognitively normal individuals (n = 124) and individuals with early‐symptomatic Alzheimer disease (n = 11). Elevated [(18)F]flortaucipir retention was observed in the two LGI1 patients with hippocampal atrophy and persistent cognitive impairment, including one with autopsy‐confirmed Alzheimer disease. Tau neuropathology may associate with cognitive complaints and hippocampal atrophy in recovering LGI1 patients.