Authors :
Presenting Author: Fahim Barmak, MD, MPH – University of Michigan
Samirna Hanif, MD – Marshall University
Rationale:
We report a case of LGI1 autoimmune encephalitis to highlight the diagnostic challenges, the importance of early antibody testing and neuroimaging, and the potential complications during management, including infections and social instability, that impact treatment outcomes.Methods:
A comprehensive clinical evaluation was performed, including neurological examination, laboratory testing (metabolic, infectious, autoimmune panels), MRI of the brain, EEG, CSF analysis, antibody testing via cell-based assay, malignancy workup (CT, PET, bone marrow biopsy, and lesion biopsies), and neuropsychological assessment. The patient was managed with immunotherapies and monitored longitudinally for response and relapse.Results:
A 66-year-old male presented with a two-week history of progressive memory impairment and altered mental status. Initial workup was unremarkable except for the presence of anti-LGI1 antibodies in both serum and CSF, confirming the diagnosis. Brain MRI showed bilateral T2/FLAIR hyperintensities in the mesial temporal lobes. EEG demonstrated bitemporal slowing and sharp waves. No malignancy was identified on imaging, though a pelvic mass biopsy showed nonspecific inflammatory infiltrates and a concurrent anal mass revealed a sessile serrated adenoma. The patient began IVIG therapy, which was discontinued due to Streptococcus pyogenes bacteremia. He was subsequently treated with corticosteroids, plasmapheresis, and rituximab. Clinical course was complicated by recurrent infections and social instability. Despite some improvement, the patient experienced relapses and demonstrated impaired decision-making on neuropsychological testing.
Conclusions:
This case underscores the diagnostic complexity and relapsing course of LGI1 autoimmune encephalitis. Key diagnostic features include characteristic MRI and EEG findings and detection of anti-LGI1 antibodies. Early and aggressive immunotherapy improves outcomes but may be hindered by infections and psychosocial instability. A multidisciplinary approach, including neurologists, immunologists, psychiatrists, and social services, is essential for optimal long-term management.Funding: