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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Essential tremor is the most common form of abnormal tremor. It is a monosymptomatic disorder characterized by action tremor but no other sign of motor dysfunction. More than half of all cases are inherited through a Mendelian dominant gene. Mild essential tremor is probably the cause of tremulousness that is frequently attributed to aging. The prevalence of essential tremor increases with age, and aging appears to have an independent effect on the clinical characteristics of essential tremor. Autopsies have revealed no discernible pathology. Essential tremor probably emerges from subtle pathologic transformation of a physiologic neuronal oscillator, possibly the inferior olive. A more complete characterization of the effects of aging on motor pathways may be necessary to fully understand the natural history and pathogenesis of this disorder.
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PMID:The role of aging in the clinical expression of essential tremor. 755 12

Essential tremor is the commonest of movement disorders. Although sometimes prefaced with the term 'benign', it often causes significant disability. Diagnosis is based on the clinical finding of a postural tremor, predominantly affecting the upper limbs, that is absent at rest and not associated with extrapyramidal or cerebellar signs. There are, as yet, no specific anatomical, physiological, biochemical or genetic markers for the condition. Postural limb tremors, clinically indistinguishable from essential tremor, may occur in patients who have, or will later develop, other neurological conditions; whether such patients have essential tremor is a matter of controversy that will only be resolved with a better understanding of the pathophysiology of essential tremor. Positron emission tomography in patients with essential tremor reveals increased cerebellar activity even at rest, a finding that is consistent with the cerebellum having an important role in the generation of tremor. Abnormal cerebellar function has also been invoked to account for the abnormal manner in which patients with essential tremor perform rapid voluntary wrist movements. Molecular genetic studies in hereditary essential tremor have been initiated, but with negative results so far. Several new drug treatments have been tried, but with limited success; the role of thalamic stimulation and botulinum toxin in the treatment of essential tremor remains to be judged.
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PMID:Essential tremor and its variants. 758 49

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

Essential tremor (ET) is typically 4 to 12 Hz frequency, absent at rest, maximal during maintenance of a posture, attenuated during movement and often accentuated at the termination of movement. Prevalence in Americans is 300 to 415 per 100,000 population, and it is frequently disabling. There is controversy about the central or peripheral origin of ET. There is no specific diagnostic test for ET; the diagnosis is made clinically. Ethanol is the most effective suppressor of ET. Treatment is with beta-adrenergic blockers, primidone, and benzodiazepines. The first systematic description of essential tremor (ET) was 100 years ago by Dana in 1887, who regarded the disorder as a hereditary tremor that was a form of "motor neurosis." Most subsequent contributions to the English literature consisted predominantly of case reports until Critchley's exhaustive survey of the subject in 1949. The disorder has been variously termed essential, benign essential, hereditary, familial, idiopathic, juvenile, presenile or senile tremor.
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PMID:Essential tremor: an overview. 791 60

There has been debate as to whether essential tremor has a central origin and over the possible role of the inferior olivary nucleus in its genesis. We used positron emission tomography with radioactive water (H2(15)O) to detect abnormal patterns of cerebral activity associated with this condition, at rest, without tremor, and on posture when the tremor was present. At rest, cerebellar blood flow was significantly increased bilaterally in the group with essential tremor (30-40%) but no increased olivary activity was evident. Essential tremor during arm extension was associated with further abnormal increases in bilateral cerebellar and abnormal red nuclear activation. Again, no olivary overactivity was evident. Voluntary wrist oscillation in control subjects caused only ipsilateral cerebellar activation. We conclude that essential tremor is associated with abnormal bilateral overactivity of cerebellar and red nuclear connections but found no evidence of intrinsic overactivity of the inferior olivary nucleus, as evidenced by raised blood flow.
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PMID:Red nuclear and cerebellar but no olivary activation associated with essential tremor: a positron emission tomographic study. 794 96

The effect of essential tremor on the timing of rapid wrist flexion was examined in 10 patients with moderate to severe disability. The mean reaction time and motor time of the patients did not differ from the mean values of 10 healthy age- and sex-matched controls. The latencies of the triphasic agonist and antagonist EMG bursts did not differ between patients and controls. The initiation of movement was time-locked to the tremor cycle in all patients. The initial agonist muscle activation occurred in phase with the rhythmic bursts of EMG, but the onset of rapid wrist flexion occurred when the momentum of essential tremor opposed the volitional movement. Essential tremor has subtle effects on motor control that transcend oscillation per se. These effects probably contribute to the impaired performance of fine motor tasks in patients with advanced disease.
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PMID:Essential tremor entrains rapid voluntary movements. 815 23

Essential tremor (ET) has been described as a monosymptomatic disorder. In reports describing large series of patients with ET, there are rare patients who exhibit a noticeable gait disorder. However, we have observed that patients with ET and normal gait often exhibit an abnormality of tandem gait. To investigate this observation, we examined whether a gait disorder was present in 36 consecutive patients (mean age 69) with ET. We employed a tremor rating scale that scored tremor amplitude, location, and disability. In all patients, gait and tandem gait were separately evaluated. Eighteen of 36 patients (50%) exhibited tandem gait abnormalities in the presence of a normal narrow-based gait compared to 11 of 40 age-matched controls (28%) (p < 0.05). Abnormality of tandem gait was more frequently present in older ET patients and those with > 5 years of disease duration. No relationship was found between presence of tandem gait abnormality and gender, tremor severity, head involvement, or positive family history. The finding of a tandem gait abnormality in 50% of ET patients suggests that cerebellar dysfunction may be important in its pathophysiology.
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PMID:Gait abnormality in essential tremor. 819 82

Among involuntary movements, dystonia is defined as abnormal posturing produced by slow sustained muscle contractions. On the contrary, myoclonus is characterized by sudden shock-like contractions of a muscle or a group of muscles. The electromyogram (EMG) in dystonia shows continuous activity lasting 5 seconds or more. The muscles usually co-contract in the antagonists. In myoclonus the muscle bursts on EMG last usually between 10 and 50 ms. In some cases the bursts last longer, but they are 200 ms at most. Thus, the characteristics of myoclonus is quite different from those of dystonia. There are, however, unusual combination of dystonia and myoclonus. Myoclonic dystonia, in which myoclonic jerks are so severe that crucial dystonic posturing may be ignored, has been reported. Essential tremor, writing tremor and writer's cramp (writing dystonia) and myoclonic writer's cramp are sometimes seen in one family in various combination. It is suggested that there may be pathophysiological relationship between dystonia and myoclonus, although these two movement disorders have different clinical characteristics.
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PMID:[Pathophysiology of involuntary movements--dystonia and myoclonus. Symptomatological view]. 875 4

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder that is generally considered to be nonfamilial. We report a brother and sister with clinical and pathologic findings characteristic of PSP. Both developed parkinsonism in the eighth decade of life and within 5 years exhibited severe postural instability, bradykinesia, rigidity, dystonia, dysarthria, dysphagia, urinary incontinence, pseudobulbar palsy, and supranuclear oculomotor dysfunction but no tremor. Neither responded to levodopa and/or carbidopa. Their mother and, possibly, maternal grandfather reportedly suffered from a parkinsonian syndrome. Essential tremor occurred in the siblings' father and in two of the brother's three children. Autopsy in the brother at age 81 years and sister at age 79 years revealed changes typical of PSP with atrophy and neurofibrillary tangles in the globus pallidus, subthalamic nucleus, and rostral tegmental brainstem. No Lewy bodies were present. These cases are the first pair of relatives reported with autopsy confirmation of PSP in both and raise the question of genetic predisposition to PSP.
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PMID:Autopsy-proven progressive supranuclear palsy in two siblings. 878 66

In this general review of tremors, one must distinguish the parkinsonian rest tremor, which concerns relaxed muscles, from other tremors that accompany muscle activities, such as maintaining a posture or executing a movement. Among various postural and action tremors, essential tremor occupies first place, in terms of its prevalence. The diagnosis of essential tremor is based on precise criteria. Often hereditarily transmitted, essential tremor can sometimes be quite disabling. Essential tremor and parkinsonian tremor are compared on an accompanying table. Other types of tremor are reviewed according to their possible prevalences. i.e. iatrogenic tremor and dystonic tremor. Particular attention is paid to orthostatic tremor, multiple sclerosis tremor and psychogenic tremor.
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PMID:[Tremors]. 920 74


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