An 84-year-old woman presented with three days of progressive fever and confusion. MRI brain showed T2-weighted hyperintensity of the right temporal lobe with patchy diffusion restriction. Cerebrospinal fluid (CSF) was positive for HSV polymerase chain reaction (PCR). Treatment with IV acyclovir lead to initial improvement. After one week she deteriorated with worsening confusion. Serum LGI-1 antibody returned positive by cell-based assay. She was treated with 5 days of IVIG; however, her mental status continued to decline.

On exam she was minimally verbal and had intermittent episodes of brief left facial grimacing with contraction of the left arm consistent with facio-brachial dystonic seizures. Repeat CSF after 21 days of acyclovir showed 76 white blood cells and elevated protein (89), negative CSF HSV PCR, and positive CSF and serum anti-LGI-1 antibodies. After five days of IV methylprednisolone and continued acyclovir, she was following basic commands but did not improve further over two weeks, at which point, decision was made to give rituximab. Due to patient’s advanced age, frail status, and prolonged hospitalization, she required feeding tube and had several infections, resulting in transition to palliative care.