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

In the Parkinsonian syndrome tremor is the symptom which still eludes pharmacological therapy. The authors report the results of nine cases of Parkinsonian tremor in which agonist and antagonist drugs acting on the receptors were employed. These were dopaminergics, acetylcholinergics, serotoninergics, histaminics, and alpha- and beta-adrenergics. The data obtained demonstrate the involvement of all the neurotransmitters studied, some directly through quantitative modifications, others indirectly through their involvement in reciprocal functional equilibria. A sytem of equilibria is hypothesized in which the histamine: serotonin ratio is given greater emphasis. (Acta neurol belg., 1977, 77, 213-229).
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PMID:Parkinsonian tremor: a neuropharmacological study. 2 Jul 29

One hundred stereotactic thalamotomies performed for upper extremity tremor were reviewed and the spatial positions of the anterior limit of ventralis posterior (VP), the thalamic-internal capsular boundary and somatotopic areas within VP plotted with respect to the midline and the place of the anterior comissure. Considerable variability was noted as to the location of these points. The surgical results following 97 of the 100 thalamotomies were evaluated at least three months after the procedure. Fifty-six of 70 patients with Parkinsonian tremor had complete abolition of their upper extremity tremor, as did 20 out of 27 patients with intention tremon. Plotting the spatial positions of the lesions in those cases in which the tremor was abolished and those cases in which tremor continued revealed little difference. However, in all of the cases in which upper extremity tremor was totally abolished, the lesion site was situated in ventralis lateralis anterior to the VP representation of the buccal commissure, thumb, or index finger. This study not only demonstrates the wide range of individual spatial variability in thalamic structures, and the necessity for neurophysiologic corroboration of radiologic information during stereotactic surgery if optimal results are to be obtained, but also suggests a somatotopic organization within ventralis lateralis.
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PMID:Thalamic spatial variability and the surgical results of lesions placed with neurophysiologic control. 35 61

1. Tetrahydropapaveroline (THP) and isoprenaline have been compared for effects on heart rate, diastolic blood pressure and contractions of soleus and tibialis muscles in chloralose-anaesthetized cats and on in vitro guinea-pig soleus muscles. 2. All effects of THP were similar to those of isoprenaline. Maximal responses were the same and responses to both drugs were antagonized by propranolol. 3. THP produced an increase in heart rate, a fall in diastolic blood pressure and a decrease in the tension and degree of fusion of incomplete tetanic contractions of the soleus, being, respectively, 12.9, 14.7 and 19.6 times less potent than isoprenaline. The similarity in potency ratios suggests that THP is a non-selective beta-adrenoceptor agonist. 4. Effects on the guinea-pig soleus in vitro were similar to those in the cat soleus. 5. In the cat, THP enhanced the tension and duration of tibialis twitches, but the tibialis was about ten times less sensitive than the soleus to the effects of THP. 6. THP deepened neuromuscular blockade in partially curarized cat soleus and tibialis preparations. Doses required were ten times greater than for direct depressant effects on the soleus. 7. Agents which depress the tension and fusion of incomplete tetanic contractions of the cat soleus via beta-adrenoceptor stimulation cause tremor in man by peripheral effects on slow muscle fibres. THP is likely to exert such actions. This may explain why levodopa (a precursor of THP) sometimes precipitates a tremor crisis in Parkinsoniam patients, and why Parkinsonian tremor is relatively refractory to levodopa therapy. In such patients combination therapy with levodopa and a peripheral dopa decarboxylase inhibi;or (to reduce levels of THP) or a beta-adrenoceptor antagonist (to block the effects of THP on slow muscle fibres) could be advantageous.
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PMID:Actions of tetrahydropapaveroline on the cardiovascular system and skeletal muscles of the anaesthetized cat and on guinea-pig soleus muscle in vitro. 69 77

Fourier analysis was used to investigate the role of perceptual information in controlling repetitive finger tapping in a patient with unilateral Parkinsonian tremor. The results are interpreted in the context of Von Holst's theory of relative co-ordination, and demonstrate the subject's reliance on extrinsic information to counteract tremor when performing voluntary repetitive movement.
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PMID:Voluntary vs autonomous control of repetitive finger tapping in a patient with Parkinson's disease. 259 72

It is important to distinguish between the different modalities of tremor. The enhanced physiological tremor is different from the essential tremor, the Parkinsonian tremor and the cerebellar tremor. They can be clearly distinguished, but can combine in single patients. The patterns for physiological mechanisms are mentioned as well as recommendations for different types of tremor are given.
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PMID:[Tremor. Pathophysiology, differential diagnosis and treatment]. 281 11

An analysis method to detect the presence of feedback between biological signals, particularly those associated with the central nervous system, is presented. The technique is based on recent results in the system identification literature involving the concept of a feedback free process. It may be applied to volume conducted signals such as EEG and EMG, as well as to neuronal spike trains through the use of a data transformation procedure. The utility of the technique is then demonstrated in a study of the relationship between Parkinsonian tremor and certain tremor cells found in the thalamus of Parkinsonian patients, using data collected during thalamotomies. The results obtained suggest that feedback mechanisms may be an important factor contributing to Parkinsonian tremor.
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PMID:Detection of feedback in the central nervous system using system identification techniques. 292 25

A method for the analysis of vocal tract parameters is developed, aimed to perform quantitative analysis of rigidity from speech signals of Parkinsonian patients. The cross-sectional area function of the vocal tract is calculated using pitch synchronous autoregressive moving average (ARMA) analysis. The changes in Parkinsonian subjects of the cross-sectional area during the utterance of sustained sounds are attributed to both Parkinsonian tremor and rigidity. In order to isolate the effects of the rigidity on the vocal tract from those of the tremor, an adaptive tremor cancellation (ATC) algorithm is developed, based on the correlation of tremor signals extracted from different locations of the speech production system.
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PMID:Analysis of vocal tract parameters in parkinsonian speech. 320 67

Twenty-eight cases of mirror writing were seen during a period of three and a half years. These consisted of 12 patients with essential tremor, nine with Parkinson's disease, three with spino-cerebellar degeneration and four other cases. There were no cases of hemiparesis, aphasia, apraxia, agnosia or confusion. Fragmentary reversals were excluded from this study. Since essential tremor, Parkinsonian tremor and cerebellar tremor can be abolished by a stereotaxic produce applied to the thalamus, a common neural pathway via the thalamic nuclei may exist in these disorders. The existence is therefore proposed of some neural mechanism that controls the higher cerebral function of writing via the thalamus.
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PMID:The aetiology of mirror writing: a new hypothesis. 343 91

A computer simulation of tremor using a mathematical model is presented, which integrates the traditional two theories; 'peripheral feedback theory' for physiological tremor and central oscillator theory' for Parkinsonian tremor. The model includes a basic stretch-reflex loop, which is modulated by the central nervous system through the gamma fibres. Fatigue of intrafusal fibres, which results from chronic stimulation by the gamma system, is assumed to be the main cause of Parkinsonian tremor. A computer simulation using the model shows that both physiological tremor and Parkinsonian tremor can be caused by the varying contractivity of the intrafusal fibres.
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PMID:Computer simulation of parkinsonian tremor. 395 Dec 9

Thirty patients with various extrapyramidal movement disorders were treated for prolonged periods with 75 to 225 mg. daily of tetrabenazine. In patients with choreiform and hemiballistic motor activity the involuntary movements were diminished or abolished. In patients with cerebellar or Parkinsonian tremor the tremor was aggravated in moderately severe cases, but was uninfluenced in severe cases. In all cases the dyskinesia returned when- the drug was stopped.Side-effects were inconsiderable and disappeared on reducing the dose slightly. Hence the drug may be an important alternative to neurosurgical treatment of hyperkinesias and especially suitable for severely disabled patients.
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PMID:Effect of tetrabenazine on extrapyramidal movement disorders. 423 53


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