BRIEF TITLE * (in English and Sufficiently Descriptive) Role of MRI in Anti-LGI1 Encephalitis

Investigating the Prognostic Role of Brain MRI in Anti-LGI1 Encephalitis

The term "autoimmune encephalitis" denotes an heterogenous group of diseases commonly associated with autoantibodies targeting neural or glial antigens. Patients harboring antibodies against the leucine-rich glioma-inactivated protein 1 (LGI1) usually respond well to immunotherapy, but a significant percentage develop cognitive sequelae and disability nonetheless. These patients would likely benefit for more aggressive and prolonged immunotherapy, aiming to prevent permanent neurological deficits. Identifying features predicting poor outcome would be crucial to guide treatment decisions. Brain magnetic resonance imaging is a key diagnostic tool in the acute phase, but radiological changes may also appear in follow-up studies, including global brain atrophy, hippocampal atrophy and mesial temporal sclerosis. We hypothesize that specific changes identifiable in the acute and chronic phase underlie a higher risk of poor outcome and persistent neurological deficits.

Inclusion Criteria:

• - Patients with a definite diagnosis of LGI1-antibody-associated encephalitis
• available MRI records
• Ascertained positivity for LGI1-antibodies in serum and/or CSF

Exclusion Criteria:

• - Positivity for another antibody against neural or glial antigens
• MRI images not available
• Not enough clinical data to ascertain outcome