Essential Tremor.

Essential tremor is one of the most common movement disorders. It is characterized by a bilateral action tremor of the upper limbs. It may be accompanied by tremor of the head, voice, or lower limbs. Essential tremor is often present for years or decades before presentation and it progresses insidiously. It is often familial and transiently responsive to alcohol. For patients requiring treatment, the two first-line medications are propranolol and primidone, which are synergistic. Patients with disabling essential tremor that cannot be managed medically are candidates for either deep brain stimulation or focused ultrasound.