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

Background: The clinical presentations of postural Parkinsonian tremor are variable and different types of tremors have been described. The aim of this study was to re-evaluate the clinical and electromyographic (EMG) pattern of different tremors in Parkinsonian patients.Methods: One hundred and ten patients with Parkinsonian tremor were included in the study. Patients were subdivided into four groups according to the presence or absence of postural tremor, in addition to a resting tremor and its EMG pattern. The first group consisted of patients without postural tremor. The second group consisted of patients with fast postural tremor (>7Hz). The third group consisted of patients with slow postural tremor with alternating EMG activity. Patients with slow postural tremor with synchronous EMG activity were included in the fourth group. In each limb position, the tremor of the most involved body part was graded on the Webster Tremor Scale. Surface EMG recordings of the most involved limb in all positions were performed.Results: Postural tremor in addition to the rest one was found in 84% of the patients. The postural tremor was with lower amplitude than the rest one. The frequencies and EMG patterns of the postural tremors were different and correlated with some specific clinical symptoms. Patients with alternating postural tremor had a kinetic and intention tremor in addition.Conclusions: Four different subtypes of Parkinsonian tremor were found according to the presence and type of postural tremor. These subtypes had some differing clinical characteristics and probably different relationships to essential tremor.
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PMID:Clinical and electromyographic examinations of Parkinsonian tremor. 1090 Mar 98

Parkinsonian tremor is most likely due to oscillating neuronal activity within the CNS. Summarizing all the available evidence, peripheral factors only play a minor role in the generation, maintenance and modulation of PD tremor. Recent studies have shown that not a single but multiple oscillators are responsible. The most likely candidate producing these oscillations is the basal ganglia loop and its topographic organization might be responsible for the separation into different oscillators which, nevertheless, usually produce the same frequency. The neuronal mechanisms underlying these oscillations are not yet clear, but three hypotheses would be compatible with the presently available data from animal models and data recorded in patients. The first is a cortico-subthalamo-pallido-thalamic loop, the second is a pacemaker consisting of the external pallidum and the subthalamic nucleus, and the third is abnormal synchronization due to unknown mechanisms within the whole striato-pallido-thalamic pathway leading to a loss of segregation. Assuming the oscillator within the basal ganglia pathway, the mechanism of stereotactic surgery might be a desynchronization of the activity of the basal ganglia-thalamo-cortical or the cerebello-thalamo-cortical pathway.
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PMID:The pathophysiology of parkinsonian tremor: a review. 1108 2

Coordination of voluntary discrete motor responses with ongoing background activity like tremor is investigated for the single-muscle multiple-task condition by experimental and theoretical work. It is shown that the periodic background activity entrains the discrete responses. The experimental results are described by a model of the motor execution stage, and several possible consequences of the model for the motor behavior in Parkinsonian tremor patients are discussed.
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PMID:Is tremor an inherent feature of an intact but misadjusted motor control system? 1169 93

The aim of this work was to examine the segmental motoneuron activity as a possible mechanism of tremor generation. Eighty-three patients with different types of tremor (25 with Parkinsonian, 29 with essential, and 30 with enhanced physiological tremor due to anxiety), 25 Parkinsonian patients without tremor and 30 healthy volunteers were examined. The tremor was studied clinically and by electromyography in all limb positions. The F wave was examined for assessment of motoneuron activity. The wave was recorded after stimulation of the ulnar, median, tibial and fibular nerves. The maximal and mean F wave amplitudes, frequency of occurrence and number of phases were increased, and the duration was prolonged in all group of patients as compared to the healthy persons. The maximal and the mean F/M amplitude ratios, as well as the Fmean./Fmax amplitude ratio were increased in all groups of patients. All F wave parameters were most altered in Parkinsonian tremor patients followed by patients with rigidity. In conclusion increased motoneuron activity participates in generation of different types of tremor and in Parkinsonian rigidity.
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PMID:Motoneuron activity in patients with different types of tremor. 1177 61

The thalamus is assumed to be involved in the generation of Parkinsonian tremor. Ten patients with tremor-dominant idiopathic Parkinson's disease (IPD) and strictly unilateral resting tremor were investigated by cerebral high-resolution 3-dimensional magnetic resonance imaging (MRI). MRI data were analyzed by an observer-independent morphometric technique, voxel-based morphometry (VBM). For VBM, MRI data were automatically normalized and segmented, then gray matter volumes were analyzed on a voxel-by-voxel basis in comparison to an age-matched control group using Statistical Parametric Mapping (SPM99). Highly significant structural changes, i.e. locally increased gray matter concentrations (P<0.001), were found in the nucleus ventralis intermedius (VIM) of the thalamus contralateral to the tremor side and were significantly covariant with tremor amplitudes. On the one hand, these changes were localized in close vicinity to a thalamic focal hypermetabolism as revealed by a previous positron emission tomography study in unilateral Parkinsonian tremor patients. On the other hand, the localization of the focal structural changes in VIM corresponds with the generally accepted target area of tremor surgery in IPD.
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PMID:Thalamic gray matter changes in unilateral Parkinsonian resting tremor: a voxel-based morphometric analysis of 3-dimensional magnetic resonance imaging. 1191 83

This study statistically evaluated a set of commonly measured tremor parameters to determine their individual and combined ability to discriminate between essential tremor (ET) and Parkinsonian tremor (PT). Accelerometer and surface electromyographic (EMG) records of moderate to severe upper limb tremor in 20 patients with ET and 22 patients with PT were used to quantitatively compare tremor amplitude, frequency and pattern of muscle bursting in two resting and three non resting postures. The group statistics showed significant differences between ET and PT with respect to tremor frequency in all five postures, tremor amplitude at rest and muscle bursting patterns. Discriminant function analysis showed that no single parameter or combination of parameters was able to correctly classify all patients. Frequency was much more discriminating than amplitude or muscle bursting patterns in all limb postures. The best amplitude discrimination was obtained when the hand and forearm were both fully supported. Muscle bursting patterns were poorly discriminating and did not assist in correct classification of single patients. Group statistics confirmed a highly significant biological difference between the two tremor types. Optimal classification of single PT (86% correct) and ET (95% correct) patients was obtained using frequency and two selected amplitude parameters from the resting limb. Limb posture was an important variable in optimising the discriminative ability of tremor studies. The implications for routine tremor studies are summarised.
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PMID:The contribution of tremor studies to diagnosis of parkinsonian and essential tremor: a statistical evaluation. 1209 26

Voluntary finger-nose movements of the arm were analysed in six patients undergoing stereotaxic nucleus ventralis intermedius thalamotomy for relief of severe Parkinsonian tremor. In all cases thalamotomy acutely abolished tremor in the contralateral arm. In the early postoperative phase, ataxia of the arm contralateral to the operated side was also seen. Ataxia was transient, lasting between 7 and 21 days postoperatively. This observation suggests that a lesion of the Vim nucleus interrupts cerebellar input to the thalamus, and supports the concept that abnormal cerebellar activity is an important contributor to the generation of tremor in Parkinson's disease.
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PMID:Ataxic arm movements after thalamotomy for Parkinsonian tremor. 1253 64

Considerable evidence indicates that cholinomimetic-induced tremulous jaw movements in rats share many characteristics with human Parkinsonian tremor, and several antiparkinsonian drugs suppress cholinomimetic-induced tremulous jaw movements. The present study investigated three different types of dopamine agonists, which have known antiparkinsonian characteristics, for their ability to suppress the tremulous jaw movements induced by tacrine (5.0 mg/kg). The non-selective dopamine agonist pergolide, a widely used antiparkinsonian drug, was highly potent at suppressing tacrine-induced jaw movements (e.g. 0.125-1.0 mg/kg). The selective D2 agonist ropinirole, which also is used clinically as an antiparkinsonian drug, suppressed jaw movements in the dose range of 2.5-20.0 mg/kg. The D1 agonist CY 208-243, which has been reported to suppress tremor, also reduced jaw movement activity (4.0 mg/kg). Across several studies, the rank order of potency for suppressing cholinomimetic-induced jaw movements in rats is related to the potency for producing antiparkinsonian effects in humans. Together with previous studies, the present results suggest that cholinomimetic-induced jaw movements in rats can be used to characterize dopaminergic antiparkinsonian agents and to investigate the basal ganglia circuits involved in the generation of tremulous movements.
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PMID:Dopamine agonists suppress cholinomimetic-induced tremulous jaw movements in an animal model of Parkinsonism: tremorolytic effects of pergolide, ropinirole and CY 208-243. 1558 3

It has been postulated that Parkinsonian action tremor is distinct from classical resting tremor and that it may contribute to a loss of manual dexterity in Parkinson's disease. We analyzed pinch grip coordination in 20 patients with Parkinson's disease. An object with and without an additional 500 g weight was grasped, lifted and held for a short time with opposed thumb and index finger. Force sensors recorded the force exerted by both fingers. Spectral analysis of the force traces was performed. Transition times between grasping and lifting the object were measured. 18 age matched normal volunteers served as a control group. While holding the object, there were force oscillations in the 3.5-6.5 Hz band indicating (reemerging) classical Parkinsonian tremor in 65% of the patients. This was reduced to 15-20% under levodopa. Oscillations in the 6-15 Hz band were found in 30% (50% with weight) of the patients, remaining unchanged under levodopa, and in 10% (20% with weight) of the normal controls. During lift initiation, 6-15 Hz oscillations were found in all patients and the majority of controls. The band power was positively correlated with the movement transition times in the severely akinetic patients and was significantly higher than in controls. It remained unchanged under levodopa. Our data confirm that Parkinsonian action tremor activated during complex voluntary movements is distinct from classical resting tremor. It does not show a clear levodopa response but affects dextrous movement coordination when associated with clinically severe overall akinesia.
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PMID:Parkinsonian action tremor: interference with object manipulation and lacking levodopa response. 1589 52

In detailed simulations we present a coordinated delayed feedback stimulation as a particularly robust and mild technique for desynchronization. We feed back the measured and band-pass filtered local filed potential via several or multiple sites with different delays, respectively. This yields a resounding desynchronization in a naturally demand-controlled way. Our novel approach is superior to previously developed techniques: It is robust against variations of system parameters, e.g., the mean firing rate. It does not require time-consuming calibration. It also prevents intermittent resynchronization typically caused by all methods employing repetitive administration of shocks. We suggest our novel technique to be used for deep brain stimulation in patients suffering from neurological diseases with pathological synchronization, such as Parkinsonian tremor, essential tremor or epilepsy.
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PMID:Effectively desynchronizing deep brain stimulation based on a coordinated delayed feedback stimulation via several sites: a computational study. 1624 Jan 25


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