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

A model of mammalian neuro-muscular systems described previously (Oguztoreli and Stein, 1975) has been extended to include multiple reflex pathways, as have been shown to exist in primates, including man (Milner-Brown et al., 1975). A number of general mathematical properties of the extended system are described. In the final section, using computer solutions, it is shown that the presence of multiple reflex pathways can effectively reduce the tendency for oscillation which will exist if high reflex gain were concentrated in a single pathway. High loop gain is desirable for good control in any negative feedback system, so the presence of multiple reflex pathways could improve reflex control, while limiting the magnitude of tremor or other unwanted oscillations in neuro-muscular systems.
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PMID:The effects of multiple reflex pathways on the oscillations in neuro-muscular systems. 102 25

Experience with a consecutive series of 125 computerized tomographic (CT) image guided stereotaxic neurosurgical procedures, performed using the Brown-Roberts-Wells (BRW) system is described. Operative objectives included tissue sampling for diagnostic purposes, intra-operative localization of craniotomy flaps and intracerebral lesions, cyst and abscess aspiration and lesion to modulate tremor. A neuropathological diagnosis was possible in 96% of the biopsies, and lesions were precisely localized in all patients undergoing microsurgical stereotaxic craniotomy. Two patients (2.2%) undergoing stereotaxic biopsy died as a result of the procedure and one patient's hemiparesis was permanently worsened (0.8%). In only one of three patients undergoing stereotaxic thalamotomy was tremor abolished. This report confirms that CT image guided stereotaxic neurosurgery is safe, accurate and versatile. There is, however, a moderate incidence (7.2%) of lesser complications that can occur with this type of surgery. These complications, which are emphasized in this paper, are related to both the site of surgery and the neuropathology.
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PMID:CT-guided stereotactic neurosurgery using the Brown-Roberts-Wells system: experience with 125 procedures. 175 73

1. The upper limbs of normal subjects were immobilized in a way that allowed measurement of forces and movements at the thumb interphalangeal joint without significant movement elsewhere in the limb. 2. When the subject attempted to maintain a steady flexing force at the joint against a rigid stop, the actual force showed the irregular 8-11 Hz fluctuations characteristic of a 'physiological tremor'. This force fluctuation increased when the mean flexing force increased. 3. If the subject exerted his flexing force against a light complaint spring, there was an analogous irregular 8-11 Hz movement at the joint. 4. When, however, an extra inertial load was added to the terminal phalanx, flexion against a complaint spring was often accompanied by a different type of tremor. This was a more regular oscillation, of lower frequency (3-6 Hz), and of much larger amplitude. 5. The precise frequency and amplitude of this type of tremor depended on the characteristics of the added inertia and spring, in a way that could have been predicted from the responses of the joint to an imposed sinusoidal movement (Brown, Rack & Ross, 1982a). The movement appeared to arise from re-excitation within stretch reflex pathways. 6. The irregular 8-11 Hz tremor at this joint could not be attributed to reflex re-excitation, since the responses to sinusoidal movement indicated a stretch reflex whose timing would not support a movement at that frequency. It is, however, emphasized that other joints of the hand and fingers may behave in different ways.
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PMID:Different types of tremor in the human thumb. 715 23

Spontaneously occurring spike-and-wave patterns were examined in seven to eight-month-old rats of the inbred Fischer 344 and Brown Norway strains and their F1 and F2 hybrids. Neocortical activity and movement were monitored for 12 night h. Spike-and-wave episodes were identified by a three-layer back-propagation neural network. The incidence, average duration and total duration of spike-and-wave episodes were significantly higher in F1 males and F2 hybrids than in the parental strains. Male rats of the Brown Norway strain had significantly more and longer episodes than females, whereas no sex differences were present in Fischer rats. The average intraepisodic frequency of spike-and-wave patterns was significantly lower in Fischer rats than in the other groups and significantly higher in males than females. Tremor (myoclonic movements) associated with spike-and-wave episodes was absent or of very small amplitude in Fischer rats but frequent and of large amplitude in Brown Norway rats and their F1 and F2 descendants. Most of the interstrain differences were limited to male rats. Spike-and-wave episodes recurred at predictable short-term (10-30 s) and long-term (15-30 min) periods. The long-term oscillation corresponded to a similar fluctuation of motor activity. The maximum probability of spike-and-wave patterns occurred at a relatively narrow range of delta power (0-3.1 Hz) of the background EEG activity. Systemic administration of the adrenergic alpha-2 agonist, clonidine, increased the incidence of spike-and-wave episodes several-fold. The total duration of spike-and-wave episodes in the clonidine sessions (15 min) and night sessions (12 h test) correlated significantly. We suggest that several genes interact with maturational, environmental and endocrine factors, resulting in sex differences, and produce the variety of EEG and behavioral findings encountered. In addition, we submit that the clonidine test may be useful in genetic investigations of human absence epilepsies. The findings of this work demonstrate that genetic manipulation of rodents is a promising method for producing analogous models for the various forms of human absence epilepsies.
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PMID:Spike-and-wave epilepsy in rats: sex differences and inheritance of physiological traits. 770 May 22

In four new-born Braunvieh calves suffering from connate recumbency and body tremor, a hitherto not described myelination disorder of the spinal cord was examined. Bilateral symmetric hypo- as well as demyelination in several spinal tracts were the most conspicuous findings, affecting the ascending gracile funiculus, the ascending dorsolateral spinocerebellar tract, and the mainly descending sulcomarginal tract. Deficient myelin production, loss of myelin, consecutive axonal degenerations, and prominent astrogliosis within these tracts were the histological hallmarks of the disease. This possibly inherited primary myelination disorder of the spinal cord differs markedly from known hereditary neurological diseases in Brown Swiss and Braunvieh cattle, respectively, i.e. the weaver-syndrome and the spinal muscular atrophy.
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PMID:Spinal dysmyelination in new-born brown Swiss x Braunvieh calves. 828 54

Early adverse effects of a drug may be a manifestation of individual differences in drug metabolism or of different pathologic processes. These differences may influence therapeutic responsiveness. Using data from Ciba-Geigy's multicenter 10-week clinical trial, we studied the relationship between early side effects and subsequent therapeutic response to clomipramine (CMI) in obsessive-compulsive disorder. We used tabular analyses and multiple regression to evaluate associations between early complaints and change in score on the Yale-Brown Obsessive-Compulsive Scale. We also evaluated whether early complaints were drug related (i.e., true side effects). It appeared that dry mouth, constipation, dizziness, insomnia, male impotence, nervousness, palpitation, and tremor reported during the first 4 weeks were predictive of good response to CMI. Myoclonus and tinnitus appeared weakly associated with treatment success. Most of these complaints were reported more by the CMI group than the placebo group, and more during CMI treatment than before. The more common complaints may reflect an individual's ability to metabolize CMI appropriately so that adequate therapeutic blood levels are attained. The less common complaints may reflect a sensitivity to CMI's serotonergic actions.
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PMID:Relationship between early side effects and therapeutic effects of clomipramine therapy in obsessive-compulsive disorder. 883 9

Some meta-analyses have suggested that the selective serotonin reuptake inhibitors (SSRIs) are less effective than clomipramine in the treatment of obsessive-compulsive disorder (OCD). The aim of this double-blind, randomised, multicentre study was to directly compare the efficacy and safety of fluvoxamine and clomipramine in patients with OCD. A total of 227 patients were randomised to flexible doses of fluvoxamine or clomipramine (both 150-300 mg/day) for 10 weeks. Fluvoxamine and clomipramine were both clinically effective and there were no statistically significant differences between the two treatment groups, at any visit, on the National Institute of Mental Health Obsessive-Compulsive global rating scale, the Yale-Brown Obsessive-Compulsive scale (total score and obsession and compulsion subscores), the Clinical Global Impression severity of illness and global improvement subscales, the Clinical Anxiety Scale and the 17-item Hamilton Depression Rating Scale. However, there were differences in safety between the two treatments. Compared with fluvoxamine-treated patients, those treated with clomipramine had more anticholinergic side effects (dry mouth, constipation and tremor) and premature withdrawals due to adverse events (18 versus 9). The results from this controlled study indicate that fluvoxamine is as effective as clomipramine in the treatment of OCD but has a better tolerability profile. Copyright 2001 John Wiley & Sons, Ltd.
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PMID:Fluvoxamine in obsessive-compulsive disorder: similar efficacy but superior tolerability in comparison with clomipramine. 1240 54

In several species of obese animals, a group of phenethanolamine beta-agonists stimulates lipolysis and thermogenesis, resulting in the loss of body fat and weight. Brown adipose tissue is considered to be the major target tissue for the antiobesity activity of these compounds. Independent of this antiobesity activity, some of these compounds are also antidiabetic and increase muscle mass. Based on the pharmacological profile of these compounds, a beta3-receptor was proposed and characterized in mouse, rat, and humans. The beta3-receptor in brown adipose tissue has been suggested to mediate the antiobesity activity of these beta-agonists. Whether this receptor is responsible for the antidiabetic activity and whether there is a linkage between the antiobesity/antidiabetic activity and the nutrient partitioning activity is not clear. Clinical trials with these mixed beta-agonists showed marginal antiobesity effects when caloric intake of subjects was restricted. Insulin sensitivity was also improved in some of the trials designed to test the antidiabetic activity of these compounds. Side effects included tachycardia and tremor. To eliminate these side effects, a second generation of compounds was selected for its agonist activity on rat beta3-receptors. Clinical trials with these compounds have shown little increase of energy expenditure even at high doses. Successful development of an antiobesity and antidiabetic drug from this class of compounds will require the elucidation of the physiological role of the human beta3-receptor and the regulatory mechanism between fuel efficiency and feeding behavior.
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PMID:Antiobesity and antidiabetic beta-agonists: lessons learned and questions to be answered. 1635 99

Parkinson's disease is treated pharmacologically with dopamine replacement medication and, more recently, by stimulating basal-ganglia nuclei such as the subthalamic nucleus (STN). Depth recordings after this procedure have revealed excessive activity at frequencies between 8 and 35 Hz (Brown et al., 2001; Kuhn et al., 2004; Priori et al., 2004) that are reduced by dopamine therapy in tandem with improvements in bradykinesia/rigidity, but not tremor (Kuhn et al., 2006). It has also been shown that improvements in motor symptoms after dopamine correlate with single unit activity in the beta range (Weinberger et al., 2006). We recorded local field potentials (LFPs) from the subthalamic nucleus of patients with Parkinson's disease (PD) after surgery to implant deep brain stimulating electrodes while they were on and off dopaminergic medication. As well as replicating Kuhn et al., using the same patients we were able to extend Weinberger et al. to show that LFP beta oscillatory activity correlated with the degree of improvement in bradykinesia/rigidity, but not tremor, after dopamine medication. We also found that the power of beta oscillatory activity uniquely predicted improvements in bradykinesia/rigidity, but again not tremor, after stimulation of the STN in a regression analysis. However improvements after STN stimulation related inversely to beta power, possibly reflecting the accuracy of the electrode placement and/or the limits of STN stimulation in patients with the greatest levels of beta oscillatory activity.
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PMID:Local field potential beta activity in the subthalamic nucleus of patients with Parkinson's disease is associated with improvements in bradykinesia after dopamine and deep brain stimulation. 1861 92

There is growing evidence that Parkinson's disease (PD) is associated with pathological synchronous oscillatory activity in the basal ganglia. These synchronized oscillations primarily occur in the 11-30 Hz range, the so-called beta band. Studies of local field potential activity in the subthalamic nucleus (STN) of PD patients suggest that exaggerated beta band oscillatory activity can disrupt function and, in particular, may contribute to slowness of movement. It has been previously shown that the degree of beta oscillatory activity in the STN of PD patients correlates with the patients' benefit from dopaminergic medications, but not with baseline motor deficits. In a paper that was recently published in Experimental Neurology, [Kuhn A.A., Tsui A., Aziz T., Ray N., Brucke C., Kupsch A., Schneider G.H., Brown P., 2009. Pathological synchronisation in the subthalamic nucleus of patients with Parkinson's disease relates to both bradykinesia and rigidity. Exp. Neurol. 215, 380-387.] the authors further establish that the degree of suppression of beta oscillations in the STN by dopaminergic medications can predict the level of improvement in bradykinesia and rigidity but not tremor. This commentary reviews some of the recent findings on beta oscillatory activity in PD and highlights the possible role of these pathological oscillations in mediating PD symptoms.
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PMID:Pathological subthalamic nucleus oscillations in PD: can they be the cause of bradykinesia and akinesia? 1907 Jun 16


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