Autoimmune Movement Disorders

ABSTRACT OBJECTIVE This article reviews the clinical and antibody spectrum of autoimmune cerebellar ataxia and other autoimmune movement disorders. It highlights characteristic phenotypes and red flags to the diagnosis and how these rare, but treatable, disorders are integrated into a differential diagnosis. LATEST DEVELOPMENTS An increasing number of neuronal antibodies have been identified in patients with cerebellar ataxia, for example, against Kelch-like protein 11 (KLHL11), seizure-related 6 homolog–like 2, septin-3 and septin-5, or tripartite motif containing protein 9 (TRIM9), TRIM46, and TRIM67. Ig-like cell adhesion molecule 5 (IgLON5) antibody–associated syndromes have emerged as an important alternative diagnostic consideration to various neurodegenerative diseases such as Huntington disease or atypical parkinsonism. Opsoclonus-myoclonus syndrome emerged as the most relevant parainfectious movement disorder related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). ESSENTIAL POINTS Autoimmune cerebellar ataxia and other autoimmune movement disorders encompass a broad spectrum of different clinical syndromes, antibodies, and immunopathophysiologic mechanisms. Clinical acumen is key to identifying the cases that should undergo testing for neuronal antibodies. Given the overlap between phenotypes and antibodies, panel testing in serum and CSF is recommended.