Movements Mimicking Myoclonus Associated with Spinal Cord Pathology: Is this a “Pure Motor Restless Legs Syndrome”

BACKGROUND The neuroanatomic substrate of restless legs syndrome (RLS) is poorly understood, and the diagnosis is clinically made based upon subjective sensory symptoms, although a motor component is usually present. CASE REPORT We report two cases of elderly patients with spinal pathology who were referred by neurologists for myoclonus. Both had semi-rhythmic leg movements that partially improved while standing, but denied any urge to move. These movements improved dramatically with pramipexole, a dopamine agonist used for RLS. DISCUSSION We propose that this "myoclonus" is actually the isolated stereotypic motor component of RLS.