Autoimmune-Mediated Encephalitis

Autoimmune-mediated encephalitis (AE) is considered an under-recognized disease with many neurological syndromes and specific antibodies described in the past 10 years. Clinical neuroradiology, using different radiological and nuclear medicine techniques such as MRI and FDG-PET, plays a crucial role in suggesting the diagnosis of AE. Bilateral medial temporal lobe T2 hyperintensities are a diagnostic core feature in autoimmune limbic encephalitis and typically predate antibody detection. Specific antibodies are targeted against intracellular or neuronal surface antigens and suggest an either paraneoplastic or nonparaneoplastic origin. MRI is abnormal in around 70% of patients with autoimmune limbic encephalitis and has a lower sensitivity than FDG-PET. The main indication to perform MRI remains the exclusion of a broad list of differential diagnoses.