Frontal cognitive-behavioural deficits in patients with anti-leucine-rich glioma-inactivated protein 1 antibody encephalitis
Sydney Lee1, Seth Climans2, Gregory Day3, Julien Hebert4, Sarah Lapointe5, Ronald Ramos6, Claude Steriade7, Richard Wennberg1, Alexandra Muccilli8, David Tang-Wai9
1University of Toronto, 2London Health Sciences Centre, 3Mayo Clinic, 4Columbia University Irving Medial Center, 5CHUM, 6Juravinski Hospital and Cancer Centre, 7NYU, 8Saint Michael's Hospital - Multiple Sclerosis Clinic, 9Toronto Western Hospital/University Health Network
Objective:
To determine the prevalence of a frontal cognitive-behavioural phenotype in patients with anti-leucine-rich glioma-inactivated protein 1 (LGI1) encephalitis.
Background:
Cognitive impairment is a common manifestation of anti-LGI1 encephalitis and is typically defined as prominent memory deficits. We frequently encounter frontal cognitive-behavioural deficits when evaluating these patients, but this has yet to be well described in the literature.
Design/Methods:
We retrospectively identified patients from three tertiary centres in Toronto, Ontario who were diagnosed with anti-LGI1 encephalitis between October 2013 and September 2022. Patient electronic medical records were evaluated for cognitive features and frontal features were categorized based on the diagnostic criteria for behavioural variant frontotemporal dementia (bvFTD).
Results:
Fifteen patients were identified (median age 65 years [range 18–84]; 8 [53.3%] male). Fourteen (93.3%) patients had cognitive symptoms that localized to the frontal lobe. Two developed these symptoms during treatment with steroids and were therefore excluded from further analysis. The remaining 12 patients presented with behavioural disinhibition (n=11), apathy or inertia (n=5), perseverative, stereotyped or compulsive/ritualistic behaviours (n=4), hyperorality and dietary changes (n=4), a neuropsychological profile with predominant deficits in executive tasks (n=4), and loss of sympathy or empathy (n=1). Seven (46.7%) met diagnostic criteria for possible bvFTD. Of these, 3 had significant functional decline and none had neuroimaging findings consistent with bvFTD. Anterograde memory impairment was common (n=11), and patients also presented with language deficits (n=3) and difficulties with spatial navigation (n=3). Of the 12 patients with frontal symptoms, only 5 had faciobrachial dystonic seizures.
Conclusions:
Patients with anti-LGI1 encephalitis can exhibit frontal cognitive-behavioural symptoms in addition to memory impairment, and screening for these features on clinical assessment may help to identify the diagnosis. Clinicians should also consider anti-LGI1 encephalitis in the differential diagnosis of bvFTD.