Anti-leucine-rich glioma-inactivated 1 encephalitis revealed by a manic episode: insights from frontal lobe dysfunction in neuropsychiatry through neuropsychology and metabolic imaging. A case report

Federica Porpiglia; Maxime Guillaume; Evangeline Bliaux; Dimitri Psimaras; Pierre Decazes; Olivier Guillin; Maud Rothärmel; Alexandre Morin

doi:10.3389/fpsyt.2023.1168302

Anti-leucine-rich glioma-inactivated 1 encephalitis revealed by a manic episode: insights from frontal lobe dysfunction in neuropsychiatry through neuropsychology and metabolic imaging. A case report

Front Psychiatry. 2023 May 18:14:1168302. doi: 10.3389/fpsyt.2023.1168302. eCollection 2023.

Authors

Federica Porpiglia¹, Maxime Guillaume², Evangeline Bliaux², Dimitri Psimaras³, Pierre Decazes⁴, Olivier Guillin¹, Maud Rothärmel¹, Alexandre Morin^{1

2}

Affiliations

¹ Department of Psychiatry, Rouvray Hospital, University of Rouen, Rouen, France.
² Department of Neurology and CNR-MAJ, CHU Rouen, Univ Rouen Normandie, UNIROUEN, Rouen, France.
³ Department of Neurology 2-Mazarin AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.
⁴ Department of Nuclear Medicine, Centre Henri-Becquerel, Rouen, France.

Abstract

Background: Anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis is a limbic encephalitis that rarely presents as an isolated psychiatric syndrome.

Case presentation: A 70-year-old patient first presented with behavioral disorder including hyperactivity, euphoria, with disinhibition and accelerated speech associated with severe insomnia and cognitive disorder. A manic episode was diagnosed and he received various psychotropic medications with no improvement. Invesitgations were negative (MRI showed T2 aspecific hyperintensities with no hyperintensities in limbic regions and EEG was normal). He was transferred to a nursing home, with a diagnosis of neurodegenerative condition. Later, he was referred to our unit for further investigations. A cerebral 18F-FDG-PET revealed an association of frontal hypometabolism and temporal and striatum hypermetabolism and CSF analysis revealed slightly increased white blood cell counts. Plasmatic anti-LGI1 antibodies were detected. The patient was treated with intra-venous immunoglobulin (IvIg) but showed no improvement. Second-line treatment (a combination of rituximab and cyclophosmphamide) was then administered for a year, leading to an improvement of neuropsychiatric symptoms and normalization of metabolic impairment on 18F-FDG-PET.

Conclusion: In this report, we describe a novel case of a patient withanti-LGI1 encephalitis with a predominant long-term psychiatric presentation. An atypical presentation (such as atypical psychiatric symptoms, neurocognitive disorder, and hyponatremia) should prompt further investigations such as CSF analysis, considering that MRI and EEG may be normal. FDG-PET might be of interest but few data are available in the literature. Early treatment of anti-LGI1 encephalitis is crucial for overall prognosis and may delay the development of dementia in some cases.

Keywords: FDG-PET; anti-LGI1 encephalitis; autoimmune manic syndrome; behavior; limbic encephalitis.

Publication types

Case Reports