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| ==Cause== | ==Cause== | ||
| The cause of the disease is unknown (]) |
The cause of the disease is unknown (]). While no identifiable and consistent structural abnormality has been demonstrated yet to exist in the ] of every person with ET, prominent researchers including Elan D. Louis are searching actively for neurochemical and brain structure abnormalities that might be commonplace among people with ET. Usually the diagnosis is established on clinical grounds, but when suspicion exists, other potential sources of tremor (excessive ] consumption, ]s, ]) should be excluded. Tremor intensity can worsen in response to fatigue, strong emotions, hunger, cold, or other factors and can be reduced with ] in approximately 50 percent of patients. However, an over-reliance on alcohol to control tremor symptoms can sometimes lead to alcohol addiction. | ||
| There is ongoing controversy as to whether ET is related to ] and whether essential tremor should properly be considered a kind of parkinsonism. |
There is ongoing controversy as to whether ET is related to ] and whether essential tremor should properly be considered a kind of parkinsonism. While some research findings appear to suggest that ET patients face a greater than average chance of developing Parkinson's, those finding might be a misleading effect of the widespread difficulty that doctors experience when they try to distinguish Parkinson's symptoms from ET symptoms and arrive at a definitive diagnosis. | ||
| Members of a family known as the "Iowa Kindred" develop either parkinsonism or symptoms that are indistinguishable from ET; their pattern of inheritance is associated with PARK4. | |||
| ==Diagnosis== | ==Diagnosis== | ||
| Essential tremor is often found in more than one member of a family (familial tremor), in which case it is usually dominant in inheritance, or it may occur with no ]. |
Essential tremor is often found in more than one member of a family (familial tremor), in which case it is usually dominant in inheritance, or it may occur with no ]. Tremors can start as any age, from ] through advanced ages (senile tremor). Any voluntary muscle in the body may be affected, though it's most commonly seen in the hands and ]s and slightly less commonly in the ] (causing the patient's head to shake), ]s, ], ], trunk, and legs. A resting tremor of the hands is sometimes present, despite the common misunderstanding that a resting tremor is proof of Parkinson's Disease. ET is usually painless, although in some cases tremor of the head or ] causes pain, and writing can become painful quickly for a person with hand tremors who grips a pen tightly in a struggle to maintain control over penmanship. | ||
| ET does sometimes occur in combination with other neurological disorders such as ] and ]. However, there is no clear evidence that having ET predisposes a person to one of these diseases. Conflicting research results have so far made it difficult for medical researchers to say with certainty that people with ET are more likely than the general population to experience hearing loss and a reduction or complete loss of olfaction, among a wide assortment of other non-tremor symptoms, but |
ET does sometimes occur in combination with other neurological disorders such as ] and ]. However, there is no clear evidence that having ET predisposes a person to one of these diseases. Conflicting research results have so far made it difficult for medical researchers to say with certainty that people with ET are more likely than the general population to experience hearing loss and a reduction or complete loss of olfaction, among a wide assortment of other non-tremor symptoms, but credible researchers have published findings to support such claims of progressive hearing loss and progressive loss of olfaction. Other published research suggests that an impaired sense of balance prevents ET patients from walking normally. It is commonly assumed among researchers that tremors are not the only symptom of ET. | ||
| ==Symptoms== | ==Symptoms== | ||
Revision as of 04:59, 24 October 2005
Medical condition| Essential tremor | |
|---|---|
| Specialty | Neurology  |
Essential tremor is a neurological disorder characterized by shaking of hands (and sometimes other parts of the body including the head), evoked by intentional movements. The incidence is unknown, but is estimated to be as common as one person in 20, and it is the most common type of tremor and also the most commonly observed movement disorder.
Cause
The cause of the disease is unknown (idiopathic). While no identifiable and consistent structural abnormality has been demonstrated yet to exist in the nervous system of every person with ET, prominent researchers including Elan D. Louis are searching actively for neurochemical and brain structure abnormalities that might be commonplace among people with ET. Usually the diagnosis is established on clinical grounds, but when suspicion exists, other potential sources of tremor (excessive caffeine consumption, drugs, hyperthyroidism) should be excluded. Tremor intensity can worsen in response to fatigue, strong emotions, hunger, cold, or other factors and can be reduced with alcohol in approximately 50 percent of patients. However, an over-reliance on alcohol to control tremor symptoms can sometimes lead to alcohol addiction.
There is ongoing controversy as to whether ET is related to Parkinson's disease and whether essential tremor should properly be considered a kind of parkinsonism. While some research findings appear to suggest that ET patients face a greater than average chance of developing Parkinson's, those finding might be a misleading effect of the widespread difficulty that doctors experience when they try to distinguish Parkinson's symptoms from ET symptoms and arrive at a definitive diagnosis.
Members of a family known as the "Iowa Kindred" develop either parkinsonism or symptoms that are indistinguishable from ET; their pattern of inheritance is associated with PARK4.
Diagnosis
Essential tremor is often found in more than one member of a family (familial tremor), in which case it is usually dominant in inheritance, or it may occur with no family history. Tremors can start as any age, from birth through advanced ages (senile tremor). Any voluntary muscle in the body may be affected, though it's most commonly seen in the hands and arms and slightly less commonly in the neck (causing the patient's head to shake), eyelids, larynx, tongue, trunk, and legs. A resting tremor of the hands is sometimes present, despite the common misunderstanding that a resting tremor is proof of Parkinson's Disease. ET is usually painless, although in some cases tremor of the head or neck causes pain, and writing can become painful quickly for a person with hand tremors who grips a pen tightly in a struggle to maintain control over penmanship.
ET does sometimes occur in combination with other neurological disorders such as dystonia and benign fasciculation syndrome. However, there is no clear evidence that having ET predisposes a person to one of these diseases. Conflicting research results have so far made it difficult for medical researchers to say with certainty that people with ET are more likely than the general population to experience hearing loss and a reduction or complete loss of olfaction, among a wide assortment of other non-tremor symptoms, but credible researchers have published findings to support such claims of progressive hearing loss and progressive loss of olfaction. Other published research suggests that an impaired sense of balance prevents ET patients from walking normally. It is commonly assumed among researchers that tremors are not the only symptom of ET.
Symptoms
Essential tremor (ET) generally presents as a rhythmic tremor (4-12 Hz) that is present only when the affected muscle is exerting effort (i.e., it is not present at rest). Any sort of physical or mental stress will tend to make the tremor worse, often creating the false impression that the tremor is of somatic origin. It is typical for the tremor to be worse in "performance" situations, such as when making out a check at a checkout stand. This is due to the increased stress in such situations.
While ET may be progressive (sometimes rapidly, sometimes very slowly), and can in severe cases be disabling, it is not life-threatening and does not appear to shorten lifespan. (Some research suggests that people with ET actually live longer than average.) In disabling cases, ET can interfere with a person's ability to perform tasks of daily living, including feeding, dressing, and activities of personal hygiene.
People with ET often report a progressive decline in their sense of balance and their fine motor skills.
Some hard research reports suggest people with ET frequently experience mild mental symptoms that include difficulty with "word finding" (remembering an intended word when speaking) and simple short-term memory loss. However, because such symptoms are common with normal aging, it's difficult to determine if these reports are significant.
Other published reports suggest that people with ET experience personality changes that leave them pessimistic, fearful, shy, anxious, and easily fatigued.
On April 13, 2005, researchers Julián Benito-Leon and Elan D. Louis presented their findings at the American Academy of Neurology 57th Annual Meeting in Miami Beach that people with ET are more than twice as likely to develop dementia than people who do not have ET. Dr. Benito-Leon told journalists at that time, "We don’t yet know whether the dementia is due to the same underlying problem that is causing the essential tremor or whether it is caused by another problem." In their research, 7.4 percent of people with ET went on to develop dementia, compared to just 3.5 percent in a control group.
Among the recent and provocative peer-reviewed research regarding non-tremor symptoms of ET, these papers are especially noteworthy:
- A Chatterjee, E C Jurewicz, L M Applegate, and E D Louis. Personality in essential tremor: further evidence of non-motor manifestations of the disease. J. Neurol. Neurosurg. Psychiatry, Jul 2004; 75: 958 - 961.
- Lacritz LH, Dewey R, Giller C, et al. Cognitive functioning in individuals with "benign" essential tremor. J Int Neuropsychol Soc 2002;8:125–9.
- Gasparini M , Bonifati V, Fabrizio E, et al. Frontal lobe dysfunction in essential tremor: a preliminary study. J Neurol 2001;248:399–402.
- Lombardi WJ, Woolston DJ, Roberts JW, et al. Cognitive deficits in patients with essential tremor. Neurology 2001;57:785–90.
- Duane DD, Vermilion KJ. Cognitive deficits in patients with essential tremor. Neurology 2002;58:1706 discussion: 1706,.
- Vermilion K , Stone A, Duane D. Cognition and affect in idiopathic essential tremor. Mov Disord 2001;16:S30.
Treatment
Treatment of ET may or may not be attempted, depending on the severity of the tremor and the physical and social handicaps that implies. Drug treatment may include tranquilizers, beta-blockers, and antiepileptic drugs. Surgical treatments (which are generally reserved for the most severe cases) include botulism toxin injections into the affected muscles, thalotomy, and deep brain stimulation – the insertion of a "pacemaker" into the brain.
Support groups
The International Essential Tremor Foundation (IETF) provides information, services and support to individuals and families affected by essential tremor (ET). The organization encourages and promotes research in an effort to determine the causes, treatment and ultimately the cure for ET. The IETF is a worldwide organization dedicated to meeting the needs of those whose daily lives are challenged by ET. IETF, an international non-profit 501(c)(3) organization that derives its support entirely from its membership and the general public, was founded in 1988 and is guided by a board of directors and a medical advisory council. The organization's membership consists of patients, physicians, educators, parents, relatives and volunteers who provide education, community services and funding to help support tremor research.
The US-based Tremor Action Network (TAN) describes itself as "the first volunteer only 501(c)(3) nonprofit organization created by people diagnosed with essential tremor." This volunteer-run organisation provides a website with forums, FAQs, and recently started carrying a newsletter on its website.
The National Tremor Foundation (NTF), founded in 1992, is a British friendly organisation based in Essex, England, an affiliate of the International Tremor Foundation, which was founded in 1988. The organisation's primary work is production of a quarterly informational newsletter. The NTF also maintains a list of ITF medical advisors, and facilitates the formation of self-help groups. NTF was granted charitable status in 1994.
Help with computers
Tunic Software has released software to help people with essential tremor, Parkinson's Disease, and other causes of hand tremor control their computer mouse. Called 'MouseCage', the software automatically smoothes mouse cursor motion to reduce the effects of unsteady or shaky hands. MouseCage anti-tremor mouse software
IBM created a peripheral device that filters out tremoring movements of the hand. The hardware adapter, termed AMA, is connected between the computer and the input device. It is switched on or off and adjusted for tremor severity right on the device.
Other tools have also been adapted for people with tremors; for example, eating utensils which are weighted to help damp out tremor.
External Links
- Tremor Action Network (USA)
- National Tremor Foundation (UK)
- Association APTES (FRANCE)
- 'MouseCage' Essential Tremor Mouse Software
- AMA