The results redefine the in vivo characterization of chronic LGI1 VGKC-complex antibody-mediated limbic encephalitis in four areas: (i) hippocampal atrophy was selective, affecting bilateral CA3, and occurred in the absence of significant grey matter loss in brain regions outside of the hippocampus; (ii) CA3 atrophy was evident following early and later intervention; (iii) CA3 atrophy was evident in patients with and without hyperintense signal on presentation; and (iv) focal CA3 atrophy was associated with severe impairment of postmorbid episodic but not semantic autobiographical memory. Here, LGI1 is linked to hippocampal atrophy.