Orthostatic myoclonus associated with Caspr2 antibodies

Orthostatic myoclonus (OM) is a clinical phenomenon in which myoclonus of the lower limbs appears or becomes worse upon standing.1 OM usually affects patients older than 65 years and may be a frequent cause of unsteadiness upon standing in the elderly.2 Although the underlying etiology remains unclear, OM has predominantly been described in association with neurodegenerative diseases.1 We describe a patient with OM in association with antibodies against contactin-associated protein-2 (Caspr2) whose symptoms markedly improved with immunotherapy. Acknowledgment: The authors thank Dr. M. R. Rosenfeld for critical review and editing of the manuscript.