However, in many people, the disease may be relatively non-progressive and the tremor may be mild throughout life. Hand tremor is the most common form of essential tremor. It is typically biphasic and involves agonist and antagonist muscles. The frequency of the tremor is between 4 to 12 Hz. The tremor is apparent while holding the body part in a fixed position.
All tremors usually disappear during sleep.
As the disease progresses, individuals with ET experience varying degrees of functional disability and resultant handicap based on the severity of the tremor. Affected individuals may have difficulty performing everyday tasks requiring fine motor manipulation skills. Holding or manipulating small objects, such as small tools or utensils, may be difficult. Hand tremor may cause difficulties with writing, drinking fluids from a glass or cup, eating, sewing, applying makeup, shaving, or dressing, for example. In individuals with ET, the next most frequently affected area of the body is the head, followed by the voice, tongue, legs, or trunk.