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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tremor is commonly encountered in medical practice, but can be difficult to diagnose and manage. It is an involuntary rhythmic oscillation of a body part produced by reciprocally innervated antagonist muscles. Tremors vary in frequency and amplitude and are influenced by physiologic and psychological factors and drugs. Categorization is based on position, posture, and the movement necessary to elicit the tremor. A resting tremor occurs when the body part is in repose. A postural tremor occurs with maintained posture and kinetic tremor with movement. Various pathologic conditions are associated with tremors. Essential tremor, which is the most common, is postural and kinetic, with a frequency between 4 and 8 Hz, and involves mainly the upper extremities and head. Essential tremor responds to treatment with primidone, beta-blockers, and benzodiazepines. Parkinson's disease causes a 4- to 6-Hz resting tremor in the arms and legs that responds to the use of anticholinergics and a combination of carbidopa and levodopa. Tremor can also be a manifestation of Wilson's disease, lesions of the cerebellum and midbrain, peripheral neuropathy, trauma, alcohol, and conversion disorders. Treatment should be directed to the underlying condition. Stereotactic thalamotomy of thalamic stimulation is a last resort.
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PMID:Tremor disorders. Diagnosis and management. 761 10

Parkinson's disease is a common disabling disease of old age. The diagnosis of idiopathic Parkinson's disease is based on clinical signs and has poor sensitivity, with about 25% of patients confidently diagnosed as having the disease actually having other conditions such as multi-system atrophy and other parkinsonism-plus syndromes. Benign essential tremor and arteriosclerotic pseudo-parkinsonism can easily be confused with Parkinson's disease. The cause of Parkinson's disease remains unknown. Speculative research highlights the role of oxidative stress and free radical mediated damage to dopaminergic cells. Parkinson's disease is the one neurodegenerative disorder in which drugs have been demonstrated to be of value. There is now a wide variety of drugs and formulations available, including anticholinergics, amantidine, L-dopa, dopamine agonists including apomorphine, selegiline and soon to be available catechol-O-methyltransferase inhibitors. Disabling side-effects of treatment, fluctuations, dyskinesias and psychiatric problems require strategic use of the drugs available. There is an increasing potential for neurosurgical intervention.
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PMID:Parkinson's disease. 919 96

The repeated administration of nicotine at small doses, which do not produce whole body tremor or convulsion, causes tremor only in the tail (tail-tremor) of rats. The tremor is accompanied by locomotor hyperactivity without rigidity and immobility of the whole body, suggesting that the nicotine-induced tail-tremor model is useful for studying the mechanism underlying tremor associated with movement. The tail-tremor induced by nicotine was suppressed by mecamylamine, a nicotinic antagonist, but not by atropine or scopolamine, muscalinic antagonists. Moreover, the tail-tremor was suppressed by the beta-blockers propranolol and pindolol, as well as the benzodiazepines diazepam and clonazepam. Tremor at rest is observed only in Parkinson's disease, which is improved with anti-muscalinic drugs. Essential tremor is one of the typical tremors connected with movement (postural and kinetic tremor) and is improved with beta-blocker. These findings and results suggest that nicotine-induced tail-tremor is useful for the study of essential tremor in animal models.
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PMID:[Assessment of anti-tremorogenic drugs--nicotine-induced tail-tremor model]. 927 37

Essential tremor (ET), the most common movement disorder in humans, appears to be inherited as an autosomal dominant trait in many families. The familial form is called familial essential tremor (FET), which seems similar to sporadic essential tremor. ET is a cause of substantial disability, particularly in the elderly. The prevalence of Parkinson's disease and dystonia may be increased in families with ET, but other movement disorders are seldom encountered in these families. Here we report the results of a genome-wide scan for FET genes in 16 Icelandic families with 75 affected individuals, in whom FET was apparently inherited as a dominant trait. The scan, which was performed with a 10-cM framework map, revealed one locus on chromosome 3q13 to which FET mapped with a genome-wide significance when the data were analysed either parametrically, assuming an autosomal dominant model (lod score = 3.71), or non-parametrically (NPL Z score = 4.70, p < 6.4 x 10(-6).
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PMID:Mapping of a familial essential tremor gene, FET1, to chromosome 3q13. 1110 30

Essential tremor (ET) is the most common adult movement disorder, as much as 20 times more prevalent than Parkinson's disease. Estimates of the crude prevalence of ET range widely from 0.08 to 220 cases per 1000 persons, a 2750-fold difference. There has been no formal attempt to synthesize these disparate results. Our purpose is to provide an overview of existing studies, to examine methodologic issues that may account for this tremendous variability in results, and to provide a more precise estimate of the prevalence of ET. Nineteen studies of the prevalence of ET were reviewed. Factors that contribute to the broad range of prevalence estimates include (a) differences in study design that influence validity and (b) differences in characteristics of study populations that influence comparability of studies. If we limit our examination to studies that (a) provided diagnostic criteria for ET, (b) defined ET as an action tremor, and (c) used community-based rather than service-based designs, then five studies remain, and the prevalence of ET is 4.1 to 39.2 cases per 1000, a 9.6-fold difference. Four of these five provided age-stratified data. Among these four, the prevalence of ET in those over the age of 60 years was 13.0 to 50.5 cases per 1000, a 3.9-fold difference.
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PMID:How common is the most common adult movement disorder? estimates of the prevalence of essential tremor throughout the world. 945 18

The physiology differs in the many forms of human tremor. Tremors may derive from mechanical oscillations, mechanical reflex oscillations, normal central oscillators, and pathologic central oscillators. Methods of studying tremor include accelerometry and electromyography (EMG). An excellent method consists of accelerometry and EMG combined with spectral analysis and weighting of the body part, which allows separation of tremors coming from mechanical reflex and central oscillators. Physiologic tremor is a mechanical tremor with a possible contribution of the normal 8-12 Hz central oscillator; exaggerated physiologic tremor is a mechanical reflex tremor. Essential tremor (ET) comes from a central oscillator that can be easily influenced with sensory input. The classic rest tremor of Parkinson's disease (PD) comes from a central oscillator that seems less easily influenced with sensory input but can be affected by transcranial magnetic stimulation. Other tremors with central oscillators are palatal tremor and orthostatic tremor. Other tremors whose physiology involves central loops includes cerebellar tremor and cortical tremor. Neuropathic tremors may be a result of delays in peripheral loops, but central oscillators play a role in some.
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PMID:Overview of human tremor physiology. 982 94

Tremor is a common neurologic symptom that can also be incapacitating to the patient, so effective therapy is needed. The causes of tremor are heterogeneous. Essential tremor (ET) and the tremor associated with Parkinson's disease (PD) are the most common encountered in clinical practice. Beta-adrenergic blockers and primidone remain the mainstay of treatment for ET, whereas carbidopa/levodopa and anticholinergics are most beneficial in PD. However, the efficacy of various other medications has been studied in ET and PD, and also in patients with tremor resulting from other conditions, with varying results.
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PMID:Pharmacologic treatment of tremor. 982 2

Tremor is a symptom of many disorders, including Parkinson's disease, essential tremor, orthostatic tremor, cerebellar disease, peripheral neuropathy and alcohol withdrawal. Tremors may be classified as postural, rest or action tremors. Symptomatic treatment is tailored to the tremor type. Combination therapy with carbidopa and levodopa remains the first-line approach for parkinsonian tremor. Essential tremor may be amenable to propranolol or primidone. Propranolol may be useful in treating alcohol withdrawal tremor, and isoniazid may control the cerebellar tremor associated with multiple sclerosis. Clonazepam may relieve orthostatic tremor. Other agents are also available for the treatment of tremor. When medical therapy fails to control the tremor, surgical options such as thalamotomy, pallidotomy and thalamic stimulation should be considered in severe cases. Thalamic stimulation, the most recent of these surgical approaches, offers the advantage over ablative procedures of alleviating tremor without the creation of a permanent lesion.
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PMID:Classification of tremor and update on treatment. 1019 97

Aside from physiological tremor, essential tremor (ET) is by far the most common cause of tremor in humans, affecting large numbers of individuals in every human population. The crude prevalence of ET has been conservatively estimated to be between 0.4% and 3.9%, although some estimates of the prevalence of ET among the elderly are higher than 20%. Essential tremor is the most prevalent adult-onset movement disorder, and is also regarded as one of the most common neurological disorders of adults, with a prevalence that is similar to or greater than that of stroke, Alzheimer disease, migraine headache, and lumbosacral pain syndromes. Essential tremor is as much as 20 times more prevalent than Parkinson disease.
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PMID:A new twist for stopping the shakes? Revisiting GABAergic therapy for essential tremor. 1040 81

Essential tremor (ET) is the most prevalent extrapyramidal disorder, yet its diagnosis is still controversial. This article introduces new findings that pertain to this diagnostic problem. Twenty-three patients with ET were studied. Patients with parkinsonism, cerebellar signs, severe head injury, or those under neuroleptic medication were excluded. Twenty-five normal subjects served as control subjects. Visuomotor tests involving tracking and tracing along three different paths with both the right and left hands, were used. Performance was assessed by measuring test duration, directional error, the proportion of the cumulative test time during which directional error exceeded half the maximal possible level (PT50%), the mean distance from the model path, the velocity of the hand movement, and the number of tracking interruptions. In 15 of 23 patients performance was the same as in the control subjects. These patients were defined as having a "simple condition" of ET (ETs). Considerable visuomotor impairment was found in eight patients who were regarded as having a "complex condition" of ET (ETc). Patients with ETc had significantly lower tracking speed, more tracking interruptions, longer test duration, greater directional error, greater PT50%, and greater distance from path than patients with ETs or control subjects. Most patients with ET appear to have normal visuomotor capabilities (ETs) but some display significant visuomotor disturbances (ETc). Considering the presence of similar impairments in patients with early Parkinson's disease and the increased prevalence of parkinsonism in patients with ET, it is possible that preclinical parkinsonism exists in patients with ETc. Further follow up of patients with ETc is necessary to verify this possibility.
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PMID:Visuomotor performance in patients with essential tremor. 1058 74


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