| Subject | Contents |
| Definition | Essential tremor is a nerve disorder in which tremors (shakes) occur without an identifiable cause when a person is moving or trying to move. |
| Alternative Names | Tremor - essential |
| Causes, incidence, and risk factors | All people have some degree of tremor that occurs during movement,. This shaking is called physiologic (occurs normally), and it mainly involves the hands. Stressful circumstances, such as fatigue, anger, fear or using certain substances (such as coffee or cigarettes) may cause transient worsening of physiologic tremor, to the point that it may become visible to the naked eye. Essential tremor is the most common form of abnormal tremor, which resembles an exaggerated physiologic shaking. Essential tremor is worsened by the same factors that enhance physiologic tremor. Although the cause is unknown, new research shows that one part of the brain called cerebellum does not appear to function properly in patients who have essential tremor. The cerebellum is the part of the brain that coordinates muscle movements and therefore, provides accuracy and harmony to voluntary movement. Nevertheless, no evident brain lesions have been identified in patients with this form of tremor. There is evidence that there are several different types of essential tremor (such as young-onset essential tremor or essential tremor with head tremor). These types differ in their response to treatment. If an essential tremor occurs in more than one member within a family group, it is termed a familial tremor. It therefore appears that essential tremor has some genetic basis, not only because of the hereditary pattern observed in some families, but also because the identical twin (who shares the same genetic makeup) of a person with essential tremor are twice as likely as a fraternal twin (who typically shares the same number of genes as other siblings) to have essential tremor. Since some identical twins do not share this condition, environmental factors must play a role as well. Essential tremors can occur at any age but are most common in people older than 65. Essential tremor is a relatively benign condition, affecting movement or voice quality, but with no other effects. It involves a rhythmic, moderately rapid tremor of voluntary muscles. Purposeful movements may make the tremors worse, while avoiding hand movements may suppress the tremors completely. There may be difficulty holding or using small objects (such as silverware or writing utensils). Over time, the tremors may affect the hands, arms, head, voice box (larynx), eyelids, or other muscles. An essential tremor rarely involves the legs or feet. It may start in one body part but can progress to include other parts with time. |
| Symptoms | Tremors May be occasional (sporadic), temporary (episodic) or occurring at intervals (intermittent) Tremors occur at a rate of about 6 to 10 oscillations per second May affect the head, hands, arms, eyelids, voice Less commonly affects the legs and feet May not affect both sides of the body equally Worsening with voluntary movement or emotional stress Disappears during sleep Typically improves with alcohol |
| Signs and tests | There is no diagnostic laboratory test for essential tremor. The diagnosis is based on the patient's history and physical examination reavealing tremor on voluntary movement and no other abnormalities.
However, some testing may rule out other causes of tremors such as excessive caffeine intake or tobacco use, alcohol withdrawal , use of certain medications (some asthma drugs, some antidepressants, lithium, some anti-seizure drugs, etc.), hyperthyroidism , pheochromocytoma , Wilson's disease (a rare condition in which copper accumulates in the brain and liver), and other disorders. Routine laboratory tests and brain imaging studies (such as CT scan of the head, brain MRI , and X-rays), or other tests are usually normal and not routinely performed. |
| Treatment | Treatment may not be necessary unless tremors interfere with the patient's ability to perform daily activities or if they are considered embarrassing to the patient. Medications result in symptom improvement in most patients, although one out of four patients may not benefit from treatment. Two medications are considered the first line of therapy: propranolol and primidone. Propranolol blocks the action of stimulant substances called neurotransmitters, particularly compounds related to adrenaline. Primidone is an anti-seizure medication, which also modulates the function of some neurotransmitters. Both medications are considered equally efficacious. However, both have significant side effects. The side effects of propanolol include: fatigue shortness of breath (asthmatics should not use this drug) slowing of the heart rhythm nose stuffiness The problems associated with primidone include: drowsiness difficulty concentrating nausea and poor gait (walking style), balance, and coordination Other medications that may reduce tremors include anti-seizure drugs such as gabapentin, mild tranquilizers such as alprazolam or clonazepam, and calcium-channel blockers (flunarizine and nimodipine). Recently, intramuscular injections of botulinum toxin in the hand have been used to reduce tremor by weakening local muscles. If tremor is severe and interfering with functioning, surgery may also be an option to alleviate the tremor. Such surgery usually involves implanting a device called deep brain stimulator in a specific area of the brain called the basal ganglia. Caffeine , found in substances such as coffee and soda, and other stimulants should be avoided.
Alcoholic beverages in small quantities may markedly decrease tremors but can lead to alcohol dependence if used in excess. The mechanism by which alcohol decreases an essential tremor is unknown. |
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| Expectations (prognosis) | An essential tremor is not a dangerous condition, but it can be annoying and embarrassing. |
| Complications | If it is severe, essential tremor can mildly interfere with activities, especially fine motor skills such as writing. Speech is occasionally involved. Medications can cause side effects. |
| Calling your health care provider | Call for an appointment with your health care provider if essential tremor is interfering with ability to perform daily activities.
Call your health care provider if side effects of medications occur, including fainting , very slow heart rate , confusion or changes in alertness, lack of coordination, problems walking, and prolonged nausea/vomiting .
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| Prevention | Counseling, exercise and other techniques may be helpful in reducing emotional stress , which can worsen the condition.
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