Essential Tremor

Essential tremor, also called benign tremor, familial tremor, and idiopathic tremor, is a medical condition characterized by involuntary rhythmic contractions and relaxations of certain muscle groups in one or more body parts, of unknown cause. It is typically symmetrical and affects the arms, hands, or fingers, but sometimes involves the head, vocal cords, or other body parts. It is either an action tremor, intensifying when the affected muscles are used during voluntary movements such as eating and writing, or a postural tremor occurring when holding the arms outstretched against gravity, which distinguishes it from a resting tremor such as that caused by Parkinson's disease; unlike Parkinson's disease, essential tremor may worsen with action.