Hypothalamic-Bulbar MRI Hyperintensity in Anti-IgLON5 Disease with Serum-Restricted Antibodies: A Case Report and Systematic Review of Literature

Abstract

Background: Anti-IgLON5 disease is a rare neurodegenerative tauopathy that displays heterogeneity in clinical spectrum, disease course, cerebrospinal fluid (CSF) findings, and variable response to immunotherapy. Sleep disorders, bulbar dysfunction, and gait abnormalities are common presenting symptoms, and conventional brain MRI scanning is often unrevealing. Objective: To provide a comprehensive overview of the literature and to assess the frequency of symptoms, MRI findings, and treatment response in patients with IgLON5 autoimmunity in the serum and CSF or restricted to serum. Methods: We examined a 65-year-old woman with bulbar-onset IgLON5 disease with serum-restricted antibodies, and we also performed a systematic review of all confirmed cases reported in the English literature. Results: We identified 93 patients, included our case. Clinical data were obtained in 58 subjects, in whom the most frequent symptoms were sleep-disordered breathing, dysphagia, parasomnias, dysarthria, limb or gait ataxia, stridor or vocal cord paresis, movement disorders, and postural instability. Distinct MRI alterations were identified in 12.5% of cases, as opposed to unspecific or unremarkable changes in the remaining patients. T2-hyperintense non-enhancing signal alterations involving the hypothalamus and the brainstem tegmentum were observed only in the present case. Inflammatory CSF was found in half of the cases and serum-restricted antibodies in 4 patients. Treatment with immunosuppressant or immunomodulatory drugs led to sustained clinical response in 19/52 patients. Conclusion: Anti-IgLON5 autoimmunity should be considered in patients with sleep disorders, bulbar syndrome, autonomic involvement, and movement disorders, and high-field brain MRI can be of diagnostic help.