A nervous system disorder that causes rhythmic shaking.
Essential tremor most often affects the hands, though it may also affect the head, voice, arms, or legs. It's not related to Parkinson's disease.
Shaking occurs with simple tasks such as tying shoelaces, writing, or shaving. Symptoms may be aggravated by stress, fatigue, caffeine, and temperature extremes.
If needed, treatment may include drugs, such as beta blockers, and physical therapy.