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Background Down syndrome regression disorder is a symptom cluster consisting of neuropsychiatric regression without cause. This study evaluated the incidence of neurodiagnostic abnormalities in individuals with Down syndrome regression disorder and determined if abnormalities are indicative of responses to therapeutic intervention. Methods A retrospective, multi-center, case-control study was performed. Patients were required to have subacute onset and the presence of four of five symptom groups present (cognitive decline, expressive language, sleep derangement, loss of ability to perform activities of daily living, and/or a new movement disorder) and no other explanation for symptoms. Results Individuals with Down syndrome regression disorder were comparable to a cohort of individuals with only Down syndrome although had higher rates of autoimmune disease (p = 0.02, 95%CI 1.04–1.75). Neurodiagnostic abnormalities were found on EEG (n = 19, 26%), neuroimaging (n = 16, 22%), and CSF (n = 9, 17%). Pleocytosis was appreciated in five cases, elevated total protein in nine, elevated IgG index in seven, and oligoclonal bands in two. Testing within 2 years of symptom onset was more likely to have neurodiagnostic abnormalities (p = 0.01, 95%CI 1.64–37.06). In individuals with neurodiagnostic abnormalities, immunotherapy was nearly four times more likely to have a therapeutic effect than in those without neurodiagnostic abnormalities (OR 4.11, 95%CI 1.88–9.02). In those with normal neurodiagnostic studies (n = 43), IVIg was effective in 14 of 17 (82%) patients as well although other immunotherapies were uniformly ineffective. Conclusions This study reports the novel presence of neurodiagnostic testing abnormalities in individuals with Down syndrome regression disorder, providing credence to this symptom cluster potentially being of neurologic and/or neuroimmunologic etiology.

Background The objective of this study was to describe the case literature of human coronavirus infections in the nervous system of children, including from SARS-CoV-2, and to provide guidance to pediatric providers for managing the potential long-term effects on neurodevelopment of human coronavirus infections in the nervous system. Methods Using a structured strategy, the PubMed and Ovid:Embase databases were queried for articles about the clinical presentation and pathophysiology of coronavirus infections in the nervous system of children and young adults, aged 0 to 24 years. Results Of 2302 articles reviewed, 31 described SARS-CoV-2 infections in the nervous system of children and 21 described other human coronaviruses: HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1, MERS-CoV, SARS-CoV-1. Excepting MERS-CoV, we found cases of neurological disease in children from each human coronavirus. Children with non-SARS-CoV-2 infections have suffered acute flaccid paralysis, acute disseminated encephalomyelitis, encephalitis, and seizures. In addition, cases of ischemic, hemorrhagic, and microvascular strokes have occurred in children with SARS-CoV-2. Patients with multisystem inflammatory syndrome in children have suffered encephalitis, stroke, pseudotumor cerebri syndrome, and cytotoxic lesions of deep brain structures. Despite these reports, few articles evaluated the impact of human coronavirus infections on long-term neurodevelopmental domains including cognitive, language, academic, motor, and psychosocial outcomes. Conclusions Neurological manifestations of human coronavirus infections can cause severe disease in children. The case literature suggests a critical gap in knowledge of the long-term effects on child neurodevelopment of these infections. As the current SARS-CoV-2 pandemic continues, this gap must be filled to facilitate optimal outcomes in recovering children.

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