GP.03 Immune deficiencies/dysregulations underpinning childhood limbic encephalitis: a case series and literature review

Abstract

Background: Limbic encephalitis (LE) is a rare autoimmune syndrome affecting limbic system structures and causing variety of manifestations including memory changes, temporal epilepsies, and psychiatric symptoms. It is a rare disease in children but with a well-recognizable combination of clinical, neuroimaging and/or histological signature. Beyond the association with anti-neuronal auto-antibodies, no clear immune system phenotype has been associated with limbic encephalitis. Our aim is to characterize the clinical and paraclinical features of non-paraneoplasic limbic encephalitis and to correlate them with potential underlying immune deficiencies. Methods: Retrospective case series of seven patients with limbic encephalitis recruited at the Montreal Children’s Hospital (MCH) with a focus on the immune- and neuro-phenotypes, including anti-neuronal antibodies, lymphocyte sub-typing, key markers of immunoglobulin and complement systems. Literature review showed 77 cases of non-paraneoplastic non-NMDA limbic encephalitis. Results: Symptoms included temporal epilepsy (n=5), psychiatric symptoms such as ADHD or autistic symptoms (n=2), and memory changes (n=3). One patient was positive for both voltage gated potassium channel antibodies (VGKC) and anti-thyroid peroxidase antibodies (TPO) and two were positive only for anti TPO antibodies. One patient showed low CD19, and immunoglobulins. Three patients showed chronic low CD56 cell count. Conclusions: The study is still ongoing, but at least 3 patients already display some traits of immune dysregulation.