A Case of Idiopathic Immunotherapy-Responsive Autoimmune Hemichorea (P9-5.031)

Abstract

<h3>Objective:</h3> We describe a case of relapsing hemichorea in a patient without imaging or laboratory abnormalities who had excellent responsiveness to immunotherapy. <h3>Background:</h3> Hemichorea is a hyperkinetic movement disorder characterized by involuntary, arrhythmic dance-like movements affecting one side of the body. Acute or subacute adult-onset hemichorea without structural lesion or metabolic derangement suggests a possible autoimmune cause. We present the case of a 74-year-old woman with a history of anxiety and mild cognitive decline who developed rapid onset of hemichorea with concurrent encephalopathy. <h3>Design/Methods:</h3> The patient was identified through direct care. The report was formulated through chart review. <h3>Results:</h3> The patient received her second dose of the primary COVID-19 mRNA vaccine series six weeks prior to symptom onset. One day prior to symptom onset she developed a mild erythematous upper extremity rash that was responsive to antibiotics. Over several days she developed left-sided hemichorea, encephalopathy, and transient auditory and visual hallucinations. Brain MRI, EEG, brain PET, and body PET-CT were unremarkable. Serum and CSF inflammatory markers were normal. Extensive and repeated serum and CSF testing for neuronal autoantibodies was negative. Serum autoantibody testing revealed only a positive anticardiolipin IgM, which was subsequently negative after multiple repetitions. She was empirically treated with 2 g/kg of IVIg and had near-complete resolution of her hemichorea and modest improvement in encephalopathy. Five months later she relapsed with an identical presentation and again received 2 g/kg of IVIg, which substantially decreased but did not fully resolve her hemichorea. She achieved remission following an outpatient course of methylprednisolone 750 mg IV weekly for nine weeks. Four months after treatment she relapsed again, this time achieving remission after repeated IV steroids and initiation of mycophenolate maintenance therapy. <h3>Conclusions:</h3> This case demonstrates the importance of considering autoimmune etiologies of hyperkinetic movement disorders and empiric immunotherapy in patients with an unrevealing workup. <b>Disclosure:</b> Dr. Rodin has nothing to disclose. Dr. Venna has nothing to disclose. The institution of Dr. Balaban has received research support from Biogen.