''For the film see Tremors (film). For other uses, see Tremor (disambiguation).

Tremor is defined as the involuntary, spasmodic movement of a body part, or parts. This occurs through the contraction of opposing muscle groups. Alternatively, tremors are a continuous quivering of the body, especially in a rhythmic or convulsive manner.

Tremor may occur as an isolated symptom and usually of idiopathic (unknown) cause (essential tremor) or a part of the symptom constellation of another disorder (e.g. Parkinson's disease). Tremors may occur at rest (Parkinson's disease), during voluntary movements (cerebellar lesions) or during excessive activity of muscles (essential tremor, hyperthyroidism). Usually, tremors involve the hands, but they may also involve the head, face, trunk, neck, voice and legs.

Types

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Tremors can be classified into five main types; involuntary, static, dynamic, kinetic, or hereditary. Tremors can be further classified as either fine, course, slow, or rapid.

• Static tremor, or "rest tremor", is a tremor that occurs despite the limb being fully supported and at rest. It usually progresses at the rate of 4-7 Hz (hertz), and is the typical Parkinsonian tremor, though it may also occur with an essential tremor.
• Intention tremor, or "action tremor", occurs when an individual tries to perform an action.
• Postural tremor occurs when supporting a limb against gravity.

Causes

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Tremors may occur in healthy individuals due to intense fear, hunger, extreme cold, over excitement or hysteria, and excessive physical exertion and fatigue. Tremors may increase with anxiety and caffeine and cease during sleep. Tremors are frequently observed in alcoholics. Tremors are common in diseases affecting the organs or brain, and can occur as a symptom of acute pathology such as poisoning and infection. Tremors can also be the side effect of prolonged use of certain medications such as some antidepressants (amitriptyline, nortriptyline, fluoxetine, sertraline, nefazodone, etc.) and some antihistamines; the tremors caused by these medications subside after the medication is discontinued. Amongst the diseases associated with tremors, essential tremor and Parkinson's disease are the best known. Tremor can also be caused by multiple sclerosis and can also occur due to large doses of ionizing radiation.

Treatment

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Medications are used only if tremor interferes with daily life activities. Some of the drugs that can be used are clonazepam, primidone and propranolol.

Other tremors

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Ocular tremors are eye tremors that are not problem tremors, but instead normal eye tremors believed to assist in vision. (Note: Larger eye movements called saccadic eye motion are not tremors.)

See also

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• Shiver

Symptoms

Tremor | Tremor | Tremor | Tremor