「症例報告」OPSOCLONUS-MYOCLONUS-ATAXIA SYNDROME AFTER ADRENOCORTICOTROPIC HORMONE THERAPY FOR INFANTILE SPASMS IN A BOY WITH DOWN SYNDROME

Abstract

Introduction: Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare acquired autoimmune paraneoplastic movement disorder associated with neuroblastoma. Additionally, autoimmune diseases and infantile spasms are common comorbidities of Down syndrome (DS). Case report: A boy aged 1 year and 9 months with DS suffered from anti-seizure drug-resistant infantile spasms. We administered low-dose adrenocorticotropic hormone (ACTH; 0.0125 mg/kg/day) for 14 days, and the infantile spasms disappeared; however, he presented with limb myoclonus and involuntary conjugate multidirectional saccadic eye movements on day 3 after the end of ACTH therapy. OMAS was suspected and a complete workup was performed. No tumors, including neuroblastoma, were detected. Antibodies against glutamic acid decarboxylase 65 and Tr/Delta/Notch-like epidermal growth factor-related receptor were found. Two courses of intravenous methylprednisolone pulse therapy (30 mg/kg/day for three consecutive days), oral prednisolone (PSL) treatment (2 mg/kg/day for four consecutive days), and intravenous immunoglobulin treatment (2g/ kg/ 3days) were administered. OMAS symptoms resolved, and PSL tapering was initiated on day 17 after the start of immunomodulatory therapy. Conclusion: We present the case of a patient with DS who developed OMAS after ACTH therapy for infantile spasms. Paraneoplastic syndrome-associated antibody testing facilitated the early diagnosis of OMAS. The development of autoimmune diseases should be considered when ACTH therapy is used for DS.