Anti-LGI1 autoimmune encephalitis: insights from three cases with serial PET imaging

Abstract

Autoimmune encephalitis (AE) can be a disabling condition, but it is manageable when identified in its early phases. Multiple diagnostic modalities can aid the diagnosis and delineation of areas of involvement in the brain, which is essential in correlating the symptoms to their pathology. This case series focuses on three cases of anti-LGI1 encephalitis in their 3rd and 5th decades, each displaying facio-brachial dystonic seizures (FBDS) and varying symptoms, such as behavioural changes and hyperhidrosis. Their MRI brains were not conclusive, but when the patients underwent a PET scan, all three of them showed involvement of the Basal Ganglia, which reversed along with clinical improvement after standard treatment for AE. AE can be a morbid condition for a long time, but some factors that might predispose to better patient outcomes might be early diagnosis and treatment. A PET scan is a modality that might help pick up functional changes before structural changes set in, and so should be considered in the diagnostic workup. Patterns of involvement of brain areas in Anti LGI1 AE need delineation, and basal ganglia seems to be a consistent region of involvement.