Orthostatic tremors are high-frequency (13-18 Hz), rhythmic contractions of the legs that occur immediately after standing. There is often an associated sense of unsteadiness or discomfort with standing, and those affected may report a fear of falling. Symptoms improve with sitting or walking. Average age of onset is 50-60 years. The tremors are often difficult to treat and they progress over time, causing increasing disability and risk of falling. Coexisting movement disorders can be present such as Parkinson disease, atypical parkinsonian syndromes, essential tremor, or restless legs syndrome.