Essential tremor.

Essential tremor (ET) is one of the most common movement disorders. Although often considered a monosymptomatic disorder (postural and kinetic tremor), ET has more recently been considered a more heterogeneous syndrome, with motor and nonmotor features. The diagnosis is clinical and pharmacologic and surgical therapies exist. ET is frequently misdiagnosed as Parkinson disease or dystonia. The traditional notion of ET as a benign disorder has been challenged by those who view ET as a slowly progressive neurodegenerative disorder.