When the Mind Plays Tricks: LGI1 Encephalitis Mimicking Psychiatric Illness.

Autoimmune encephalitis (AE) is a rare brain inflammation caused by the immune system. Leucine-rich glioma inactivated 1 (LGI1) antibody-associated AE is more common in older men and presents with memory loss, confusion, and brief seizures called faciobrachial dystonic seizures (FBDS). We report a 66-year-old man with hypertension and high cholesterol who presented with sleep-related spasms, confusion, and cognitive decline. Early magnetic resonance imaging (MRI) of the brain and electroencephalogram (EEG) were normal, delaying diagnosis. LGI1 antibodies were later detected in his blood. He received corticosteroid treatment, showing cognitive improvement and a decrease in the number of confusion episodes. The patient's family stated that the spasms were improved after treatment. This case highlights the need for early testing and treatment, even when initial findings are normal.