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Orthostatic tremor: an essential tremor variant?

Three patients with a clear-cut history of essential tremor of the upper limbs presented with the clinical features reported by Heilman as orthostatic tremor. Electromyographic findings included 6-8 Hz postural tremor in all four limbs. Highly synchronized 16 Hz rhythmic discharges were found in the legs upon standing. This peculiar pattern of discharge was also observed in the upper limbs and spinal muscles. High frequency rhythmic bursts, either alternating or co-contracting were present in specific postures not necessarily related to standing. An additional group of 12 patients with postural tremor of the legs was studied; seven of these showed modification in the frequency and synchronization of the muscle discharges upon standing. Although none of them had the full-blown clinical syndrome of orthostatic tremor, they complained of mild unsteadiness upon standing, together with a vague sensation of stiffness in the lower limbs. The present findings induce us to think that there might be a link between essential tremor and the so-called orthostatic tremor. Orthostatic tremor might be an essential-tremor-related entity that may be caused by a derangement in the central mechanism in charge of the organization of certain motor activities, not necessarily controlling the standing position.

Aged↗

Gait abnormality in essential tremor.

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.

Aged↗

Epidemiology and genetics of essential tremor.

Essential tremor (ET) is one of the most common movement disorders. However, the etiology and pathogenesis are as yet unknown. Continued research will give us clues to understanding the impact on society, identifying genetic and environmental contributors to the disease, understanding the significance of a sporadic case, the phenotypic spectrum and timing of presentation, and the relationship with other neurologic disorders. Because the condition is both clinically and genetically heterogeneous and there is overlap with these other disorders, such as dystonia, parkinsonism, peripheral neuropathy, and migraine, the definition of phenotype plagues research in this area. Advances in understanding the genetic and molecular underpinnings of tremor should provide additional tools to unravel the clinical phenotype (including physiology), genotype-phenotype relationships, and the epidemiology of tremor.

Humans↗

Biobehavioral rehabilitation for older adults with essential tremor.

Essential tremor (ET), the most prevalent movement disorder, has a peak prevalence in the sixth decade of life. ET primarily affects the hands and head. Persons with ET are often significantly disabled in communication, work, leisure, domestic activities, and psychosocial adjustment. Medical intervention for ET is often limited in effectiveness. A biobehavioral rehabilitation model for older adults with ET is described.

Activities of Daily Living↗

Essential tremor.

Essential tremor is a common disorder whose aetiology is unknown. Characteristically it is present on maintaining posture, absent at rest, and not made significantly worse with movement.

Diagnosis, Differential↗

Essential tremor.

Essential tremor, including the juvenile and senile variations, may be a result of a disorder of the servomechanism that controls physiologic tremor. Hands and arms are affected most commonly, and the tremor can vary in amplitude as well as frequency. Long-term treatment with propranolol has been helpful for some patients, although older patients are less likely to benefit. Other drugs and behaviour modification therapy have been less successful. Surgical treatment is effective but should probably be reserved for severe cases. An effective instrument for measuring the subjective and objective aspects of the tremor is still needed, as is an effective long-term method of treatment.

Ethanol↗

Factors associated with increased risk of head tremor in essential tremor: a community-based study in northern Manhattan.

Head tremor is one of the major expressions of essential tremor (ET). It is not well understood why some patients develop head tremor, whereas others do not. A study of the characteristics of patients with head tremor has not been undertaken. Our goal was to estimate the prevalence of head tremor and to identify demographic and clinical characteristics associated with an increased risk of head tremor in ET. Cases were ascertained from a community-based study of ET in northern Manhattan, New York. Arm tremor severity was rated with a total tremor score. Logistic regression analyses resulted in odds ratios (OR). Head tremor was present in 37 (34.9%) of 106 ET cases. Female gender was associated with a fourfold increased risk of head tremor (OR = 3.73; P = 0.005). Total tremor score was divided into quartiles; individuals in the lowest or highest quartile were four times more likely to have head tremor (OR = 4.16; P = 0.001). Individuals with both risk factors (female gender and lowest or highest total tremor score quartile) were 16 times more likely to have head tremor (OR = 15.88; P = 0.0006). Being related to a proband with head tremor marginally increased the risk of head tremor (OR = 11.30; P = 0.08). Age and tremor duration did not influence the risk of head tremor. We identified several factors that were associated with an increased risk of head tremor in ET; female gender, coexisting arm tremor that was either very mild or extremely severe, and relation to an ET case with head tremor. These disease associations require further exploration, and might provide insight into the mechanisms underlying head tremor.

Adult↗

Coherence analysis differentiates between cortical myoclonic tremor and essential tremor.

Familial cortical myoclonic tremor with epilepsy (FCMTE) is characterized by a distal kinetic tremor, infrequent epileptic attacks, and autosomal dominant inheritance. The tremor is thought to originate from the motor cortex. In our patient group, a premovement cortical spike could not be established on electroencephalogram (EEG) back-averaging. Corticomuscular and intermuscular coherence analysis can demonstrate a cortical common drive to muscles. We carried out coherence analysis of electromyography (EMG) of forearm muscles and EEG of contralateral motor cortex in 7 FCMTE patients, 8 essential tremor (ET) patients, and 7 healthy controls. Results showed strong cortico- and intermuscular coherence in the 8- to 30-Hz range in the FCMTE patients, with EEG preceding EMG. Healthy controls and ET patients showed normal weak coherence around 20 Hz. The ET patients showed some additional coherence at tremor frequency (6 Hz), probably the result of sensory information flowing back to the sensorimotor cortex. These findings point to a pathological cortical drive in FCMTE patients leading to tremulous movements. Coherence analysis is an easy and useful method to differentiate FCMTE from ET. Coherence analysis is helpful when investigating a cortical common drive in cortical tremor and other movement disorders.

Adult↗

A new twist for stopping the shakes? Revisiting GABAergic therapy for essential tremor.

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.

Acetates↗

The Washington Heights-Inwood Genetic Study of Essential Tremor: methodologic issues in essential-tremor research.

Essential tremor (ET) is the most prevalent movement disorder. It is unknown to what extent ET clusters within families, and the role of genetic susceptibility in etiology of ET has not been adequately investigated at the population level. The problem is largely methodological, with few well-designed studies. The Washington Height-Inwood Genetic Study of ET, begun in 1955, is designed to investigate the genetics of ET using a methodology that has not been applied to ET research to date. Part of the design includes a new set of clinical and electrophysiological diagnostic criteria for ET; the present paper describes this novel study design.

Case-Control Studies↗

Thalamic stimulation for the treatment of midline tremors in essential tremor patients.

The authors prospectively collected unblinded data from 27 consecutive patients following thalamic stimulation. A significant reduction of midline tremor was achieved after unilateral surgery, but a staged contralateral surgery had an additional effect. A subgroup analysis showed significant beneficial effects for head, voice, tongue, and face tremor. The most frequent reversible side effects were disequilibrium, dysarthria, and paresthesias. We observed more pulse generator adjustments for speech problems in the bilaterally implanted group.

Aged↗

[Effect of Coretal Polfa (Oxprenolol) on parkinsonian tremor and benign essential tremor].

Coretal -- an agent blocking the beta-adrenergic receptors -- was given to 12 patients with Parkinson's syndrome with evident tremor and to 4 patients with benign essential tremor. In the group of Parkinson's syndrome the effectiveness of this treatment was evaluated by the blind method. The whole period of observation was 6 weeks, during 3 weeks the patients received Coretal 60-120 mg daily, during the next 3 weeks they were given placebo. The intensity of tremor was assessed by means of a scoring system. Improvement was achieved in 7 patients with Parkinson's syndrome and in 3 out of 4 cases of idiopathic tremor. Complete disappearance of tremor was never observed. Transient side effects were observed in 2 causes. The authors think that Coretal may be used with good result in treatment of parkinsonian tremor and benign essential tremor.

Clinical Trials as Topic↗

[Clinical features of essential tremor].

UNLABELLED: Essential tremor is a dominant hereditary disorder with incomplete penetration manifested in action, postural tremor with no signs of parkinsonism, cerebellar lesions or other neurological signs [1]. The diagnosis of essential tremor is established on the basis of the clinical picture, and is greatly variable and insufficiently defined [5]. MATERIAL AND METHODS: The study concerned patients with the diagnosis of essential tremor established by the International Association for Tremor Studies in 1995 where tremor was classified into definite++, possible and probable [6]. All patients were subjected to a special questionnaire including demographic and clinical characteristics of tremor. Detailed neurological examinations focusing the presence of extrapyramidal signs were carried out. Fischer's Exact test was used for statistical analysis. RESULTS: The study comprised 107 patients (55 males, 41 females), aged 17-84 years (57.3 +/- 15.6) and 7-77 (46.3 +/- 17.9) at onset of the disease. Postural tremor was present in 36% of patients, postural tremor with intentional deterioration in 16%, statopostural tremor in 21% and continuous tremor in 17% of subjects. Extrapyramidal signs were present in 31% of patients, and clumsiness in fine alternating movements was present in 17 patients. The patients with longer duration of illness were significantly more clumsy in fine alternating movements (Fischer's Exact test; p = 0.507 < 0.05), but not in the presence of extrapyramidal signs (Fischer's Exact test; p = 0.507 > 0.05). DISCUSSION: Essential tremor is described as a dominant inherited postural tremor. Koller et al. [9] describe dominantly kinetic tremor occurring with movements, while Martinelli et al. [10] describe continuous tremor manifested at rest, posture and with movements. Static tremor was considered as a result of the disease progression [8]. In our patients those with longer duration of the disease were frequently more clumsy in fine alternating movements, but not in manifestation of extrapyramidal signs. Continuous tremor is probably a subgroup of essential tremor; suggests a more pronounced role of cerebellum in its genesis.

Adolescent↗

Effect of stimulation frequency on tremor suppression in essential tremor.

We sought to determine the effect of deep brain stimulation (DBS) frequency on tremor suppression in essential tremor (ET) patients with deep brain stimulators implanted in the ventral intermediate nucleus (VIM) of the thalamus. A uniaxial accelerometer was used to measure tremor in the right upper extremity of subjects with a diagnosis of ET who had DBS electrodes implanted in the left VIM. The root-mean-square acceleration was used as the index of tremor magnitude and normalized to the OFF DBS condition. There was a highly significant inverse sigmoidal relationship between stimulation frequency and normalized tremor acceleration (X(2)/DoF = 0.42, r(2) = 0.997). Tremor acceleration had a nearly linear response to stimulation frequencies between 45 and 100 Hz with little additional benefit above 100 Hz. These findings have two important implications. Clinically, frequency of thalamic stimulation is an important variable for optimal tremor control with maximal benefit achieved with 100 to 130 Hz in most patients. Second, thalamic DBS provides tremor benefit in a graded manner and is not an all-or-nothing phenomenon.

Adult↗

The relationship of essential tremor to other movement disorders: report on 678 patients. Essential Tremor Study Group.

We examined 678 essential tremor patients in specialty, university, and private practice clinics. The mean age of patients was 65.2 years with a similar number of men and women. Six percent of patients were left-handed. A positive family history of tremor was reported in more than 60% of patients. Alcohol ingestion was reported to decrease tremor in 74% of patients who were cognizant of the effect of alcohol on tremor. Mean age at tremor onset was 45.3 years. An earlier onset of tremor was observed in those patients having a positive family history of tremor. Tremor affected the hands in 90% of patients, head in 50%, voice in 30%, and legs and chin in 15%. Functional disability was common and impairment at work occurred in 18%. Propranolol and primidone were the most frequently used drugs and were effective in 40% of patients. Six and one-tenth percent of essential tremor patients had concomitant Parkinson's disease, 6.9% had a coexisting dystonia, and 1.8% had myoclonus. It is concluded that the frequency of Parkinson's disease in essential tremor is more than would be reported in the general population and that other movement disorders are infrequently observed in essential tremor.

Aged↗