Title : When mind plays triack: Lgi1 encephalitis mimicking psychiatric illness
Abstract:
Background: LGI1 antibody-associated autoimmune encephalitis is a rare condition typically affecting older adults, presenting with seizures, cognitive decline, and behavioral changes. Diagnosis is often delayed due to normal imaging, EEG, and CSF findings. Early recognition and immunotherapy are critical to prevent long-term deficits. This case illustrates the diagnostic challenges and importance of considering autoimmune causes in subacute neuropsychiatric syndromes.
Case Presentation: A 66-year-old forklift driver presented to Walsall Manor Hospital in March 2024 with a 10-day history of brief, non-convulsive episodes (10 seconds, once or twice daily), without loss of consciousness or typical seizure features. Since February 2024, he also experienced a “butterfly” abdominal sensation, occasionally followed by limb jerks or falls. His symptoms progressed over the months to include confusion, memory loss, impulsiveness, and disinhibition. Initial blood tests showed mildly raised WBC and neutrophils, elevated ALT and GGT, and low calcium. CSF was unremarkable with no signs of infection or inflammation. The EEG and MRI brain were normal, and a cardiology review excluded syncope. Early investigations were inconclusive, and he was referred for psychiatric evaluation. Cognitive testing (ACE: 85/100, MMSE: 28/30) raised concerns for a neurological cause. In September 2024, serum LGI1 antibodies were detected, confirming LGI1 autoimmune encephalitis; other autoimmune and paraneoplastic panels were negative. Repeat testing in October reaffirmed LGI1 positivity. CSF antibody panels remained negative, suggesting disease confined to serum. In December 2024, treatment with IV methylprednisolone followed by oral steroids was initiated, with some cognitive and behavioral improvement. Despite ongoing hallucinations and insomnia (managed with melatonin), overall clinical status improved. As of February 2025, the patient showed stabilization with persistent but manageable neuropsychiatric symptoms and continued follow-up under neurology.
Conclusion: The patient who has clinical presentation of personality change and abnormal body movement had normal initial work up. While earlier it was seen that there were Non-Epileptic Attacks, it was extensive work up that showed the patient was having a rare disease – Auto-Immune encephalitis.
