SHM Converge Scientific Abstract ePoster Gallery-Lgi1 Encephalitis: A Rare Cause of Altered Mental Status

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This case report describes a 59-year-old man with hypertension and cocaine use who presented with altered mental status, progressive memory and attention problems, and recurrent episodes of left facial grimacing with sudden flexion of the left arm. His wife also noticed behavioral changes. On exam, he was oriented to person and place only, with bradyphrenia, flat affect, and impaired short-term memory and attention. Initial evaluation showed moderate hyponatremia, positive urine drug screen for cocaine and marijuana, normal CT head, and otherwise unrevealing metabolic workup.<br /><br />The patient’s episodic facial and arm movements were consistent with faciobrachial dystonic seizures (FBDS), which are strongly associated with LGI1 encephalitis. Although CT was normal, MRI revealed bilateral temporal lobe hyperintensities, and 24-hour video EEG confirmed ongoing FBDS. CSF studies later confirmed LGI1-IgG antibodies, establishing the diagnosis of LGI1 encephalitis.<br /><br />LGI1 encephalitis is an autoimmune encephalitis and the second most common type of autoimmune encephalitis. Typical features include FBDS, short-term memory loss, behavioral changes, spatial disorientation, and hyponatremia. FBDS often appear early and may precede cognitive decline, making early recognition essential. The condition usually responds to immunotherapy, with steroids as first-line treatment and plasmapheresis, IVIG, or rituximab as second-line options.<br /><br />In this case, the patient was initially treated with levetiracetam and methylprednisolone. Because seizures persisted, plasmapheresis was attempted without benefit. He ultimately improved after switching to lacosamide, with improvement in both symptoms and EEG findings.<br /><br />The report emphasizes the importance of maintaining a broad differential diagnosis in patients with altered mental status, since early recognition of LGI1 encephalitis can lead to faster diagnosis and treatment.

Asset Subtitle

Robert M. Krahmer

Meta Tag

Author List Nikesh Rohit Kapadia, Robert M. Krahmer, William Johnson

Category Clinical Vignettes

Concept LGI1 encephalitis

Concept Faciobrachial dystonic seizures

Concept Short-term memory decline

Concept Corticosteroids

Concept Intravenous Immunoglobulin

Distinguished Finalist

Presenter Organization University of South Florida

Presenting Author Robert M. Krahmer

Track Adult

Keywords

LGI1 encephalitis

faciobrachial dystonic seizures

autoimmune encephalitis

hyponatremia

altered mental status

memory loss

cocaine use

MRI temporal lobe hyperintensities

video EEG

immunotherapy

LGI1 encephalitis

Faciobrachial dystonic seizures

Short-term memory decline

Corticosteroids

Intravenous Immunoglobulin