Leucine-rich glioma-inactivated 1 limbic encephalitis (LGI1-Ab LE) is a rare cause of altered mental status (AMS). Here we present a case of a 59-year-old male who arrived at the hospital with AMS and several months of abnormal movements. He possessed several risk factors for AMS, including intoxication, possible withdrawal, and electrolyte abnormalities. However, due to his atypical symptoms, a thorough evaluation was performed, and a video-electroencephalogram was positive for faciobrachial dystonic seizures (FBDS), which are pathognomonic for LGI1-Ab LE. FBDS are a specific type of seizure characterized by brief ipsilateral contractions of the arm and face. Results from a lumbar puncture later confirmed the diagnosis, which was positive for LGI-1 antibodies. The patient’s symptoms improved with systemic steroids and lacosamide. LGI1-Ab LE is the second most common type of autoimmune encephalitis and can be challenging to diagnose. This case highlights important clinical features that can aid in early recognition, leading to improved patient outcomes.
Krahmer et al. (Tue,) studied this question.