Functional Jerky Movements

Functional jerky movements (or functional myoclonus) are commonly seen in patients with functional movement disorder. Positive features both from history and clinical examination are important for the diagnosis. However, due to their heterogeneous and paroxysmal nature a home-made video-recording of the jerky movements can be essential to make the diagnose by a movement disorder specialist. Supportive clinical clues include abrupt symptom onset often triggered by a physical event, whereas entrainment and distractibility are supportive signs during physical examination. Localization of the jerky movements, especially proximal localization, is supportive, and can also be helpful in distinguishing functional jerks from tics and myoclonus, which are the most important differential diagnostic considerations. Additional neurophysiological tests include polymyography and electroencephalography-electromyography (EEG-EMG) co-registration in order to demonstrate a readiness potential (RP). Management includes disease education and specialized physical therapy.