What is (are) Essential tremor ?
Essential tremor is the most common movement disorder.  It is characterized by involuntary and rhythmic shaking (tremor), especially in the hands, without any other signs or symptoms. It is distinguished from tremor that results from other disorders or known causes, such as tremors seen with Parkinson disease or head trauma. Most cases of essential tremor are hereditary. There are five forms of essential tremor that are based on different genetic causes. Several genes as well as lifestyle and environmental factors likely play a role in a person's risk of developing this complex condition. In mild cases, treatment may not be necessary. In cases where symptoms interfere with daily living, medications may help to relieve symptoms.