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

Two single-blind placebo-controlled crossover studies on healthy volunteers were performed to compare typical adverse effects of the beta 2-adrenoceptor agonists salbutamol, terbutaline und tulobuterol in a daily period of eight h after acute oral administration of different doses. Assessments were repeated after six days of regular drug intake, to look for habituation phenomena. Finger tremor, integrated surface-EMG in relation to voluntary force, blood pressure and heart rate were measured. Tremor was recorded with a 3-dimensional accelerometer during three different states of hand extensor muscle activity: relaxed, lightly and maximally contracted. The tremor signal was submitted to power spectrum analysis (FFT). All drug effects depended on the dose and the type of drug used, 2 mg tulobuterol being about equivalent to 4 mg salbutamol and to 2.5 mg terbutaline. Cardiovascular adverse effects were weak and transient. The induction of resting tremor showed some habituation across subchronic medication, whereas cumulative and ceiling effects of the beta 2-agonists occurred in respect to tremor during both states of active muscle contraction. However, the beta 2-adrenergic effect during strong contraction consisted in a prominent reduction of tremor. This striking result did not seem to be related to a transient increase of force, relative to myoelectric activity, which was no longer seen after subchronic medication. In case of ceiling effects, the relative changes in tremor intensity decreased with continuous beta 2-sympathomimetic treatment. Therefore, tremor might become a tolerable though inevitable concomitant of bronchodilatory therapy. Its quantitative measurement seems to provide adequate means to assess dose- and time-efficacy as well as to estimate clinical benefit.
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PMID:Induction and reduction of muscle tremor upon acute and repeated administration of the beta 2-agonists terbutaline, salbutamol and tulobuterol. 289 78

The effect of pseudo-fraction gravity on physiological tremor of the human finger (finger tremor) has been examined experimentally by immersing an index finger into water at different immersion levels. The pseudo-fraction gravity, gamma G, was established by water buoyancy at immersion level omega, G being gravitation acceleration and gamma between zero and unit. The nature of variations of finger tremor under the influence of gamma G is estimated based on FFT spectral analysis. It is illustrated that with a decrease in gamma, or equivalently an increase in omega, two dominant peaks remaining approximately constant in frequencies around 10Hz and 20Hz are found, while peak amplitude is decreased rapidly for higher peak and slowly for lower one. Theoretically the effect of pseudo-fraction gravity is analyzed in terms of a specific model for finger tremor. The experimental results presented in this paper are predicted rather well by two resonant modes which occurred in our model system. It is possible to conclude that the model, which is characterized by a pair of antagonistic muscles and two reflex pathways, provides an adequate quantitative description of finger tremor.
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PMID:Physiological tremor under pseudo-fraction gravity. 762 Nov 32

The propriety of the autoregressive (AR) method as a means of processing the signals of physiological tremor of human finger (finger tremor) was investigated. Application of the Akaike's criterion demonstrated that the 15-th order AR model was required to describe the recordings of finger tremor. According to Burg's algorithm, both AR spectrum and AR parameters were estimated to study the effects of various weight loads on finger tremor. It was found that, (1) the amplitude of AR spectrum was apparently enhanced by adding the load; (2) the first prediction coefficient (a1) and the first reflection coefficient (rho 1) significantly declined by increasing the weight loads. The results were compared with the calculations from FFT (Fast Fourier Transform) and autocorrelation function. Simple physical interpretation of the AR parameters (i.e. a1 and rho 1) was discussed in relation with system's resonant modes.
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PMID:Effects of weight load on physiological tremor: the AR representation. 762 Nov 36

Tremor is frequently encountered in neurologic practice. Clinical examination supplies information regarding its approximative frequency, regularity, amplitude, topography and activation conditions. The neurophysiological study helps in confirming the tremor, in differentiating it from other movement disorders like myoclonus, and may provide distinctive features which are important for the aetiological diagnosis. The neurophysiological investigation includes accelerometry, which analyses the mechanics of the movement. Spectral analysis with FFT allows the determination of frequency and amplitude. Accelerometry is always associated with surface EMG of at least two antagonistic muscles. It may show rhythmic bursts, their frequency, duration and activation pattern (alternating or synchronous). This neurophysiological approach to tremor has multiple interests. It may help in differentiating a true rest tremor from a postural tremor seemingly persisting at rest. Brief interruptions or rhythm breaks during distraction manoeuvers are seen in psychogenic tremors. Surface EMG may also demonstrate positive myoclonic bursts, or brief silent periods corresponding to negative myoclonus, sometimes pseudorhythmic, thus appearing clinically like a tremor, but investigations, aetiologies and treatment are different. Several features, especially slow frequency, may suggest a midbrain tremor, thus requiring brain imagery centered around the posterior fossa. Finally, the neurophysiological examination is the only way to demonstrate a primary writing tremor, or a primary orthostatic tremor, the frequency of which is pathognomonic while clinical symptoms are rather misleading.
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PMID:[Neurophysiologic study of tremor]. 1081 77

Tremor, defined as a rhythmic and involuntary oscillation of a body part, is considered one of the most common disturbances of movement. The most frequent pathological forms, mainly affecting elderly people, are the essential tremor, the Parkinson's disease tremor and the physiological tremor. In order to examine the characteristics of a tremor, methods based on accelerometry and electromyography measures and more recently spirometry test, based on a digital acquisition of hand movements drawing an Archimedes' spiral, have been used. Though the quantification of tremors is the object of study for several researchers, today a standard method does not exist yet [1]. The most common techniques examine the frequency of tremors, however there is no consensus in literature on its value among the various pathological forms. As for handwriting, characteristics of tremors can be investigated from a kinematic point of view. For this aim, in this paper new quantitative kinematic parameters are proposed and their potential is evaluated on three groups of subjects (two with pathological tremors and a control group). Each subject underwent a set of four graphical tests (Horizontal Rows, Archimedes' Spiral, Triangle and Square) and the kinematic parameters calculated on the recordings were examined in order to establish which test and parameters are more sensitive to tremor differences and appropriate for pathologies identification. Significant differences were found for the number of strokes (being the stroke the base element of each hand movement), the number of ascending / descending tracts, the zero-crossing of velocity and acceleration profiles, the line curvature, the angular velocity and the dominant frequencies values extracted from FFT analysis of velocities, especially in relation with the Rows and Spiral tests. Depending on the test, some other significant differences were found in the velocity and acceleration mean values as well as in the number of components and pen-lift intervals. The results support the hypothesis that kinematic analysis can be useful in tremor studies and when used with suitable tests it can differentiate among pathological and normal subjects.
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PMID:Kinematic analysis of tremor - biomed 2010. 2046 7