Anti-LGI1 Encephalitis

A 64-year-old man presents with multiple daily brief (1–3 second) dystonic posturing of the left face and ipsilateral arm, occurring up to 50 times per day. He also reports subacute memory loss, confusion, and insomnia over 4 weeks. Serum sodium is 126 mEq/L. MRI brain shows bilateral medial temporal T2/FLAIR hyperintensity with preserved diffusion. CSF shows mildly elevated protein without pleocytosis or oligoclonal bands. An EEG is performed. The pattern marked **B** in the diagram—brief subclinical or ictal discharges over fronto-central or temporal regions correlating with the dystonic episodes—is characteristic of which antibody-mediated encephalitis?