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At least 775 records · Page 43Linked to original sources
PubMed2003

Treatment of tremors in complex regional pain syndrome.

A 14-year-old girl presented with Complex Regional Pain Syndrome, Type I (CRPS-1) of the left ankle after a remote history of sprain. Allodynia, pain, temperature and color changes, and swelling were successfully treated with physical therapy, transcutaneous electrical nerve stimulation (TENS), gabapentin, amitriptyline, and tramadol. Five weeks later, she presented with a continuous, involuntary, intermittent coarse tremor of the left foot causing increased pain. The electromyogram showed rhythmic discharges of 3 Hz frequency lasting 20-80 milliseconds in the left tibialis, peroneus and gastrocnemius, suggestive of either basal ganglia or spinal origin. Tremor and pain were controlled with epidural bupivacaine, but the tremor reappeared after discontinuing epidural blockade. Carbidopa/levodopa 25/100 (Sinemet) was started and the tremor disappeared after two days. With continued physical therapy, pain and swelling resolved within two months and carbidopa/levodopa was discontinued after five weeks with no recurrence of the tremor. Our success in the treatment of CRPS-associated tremor in this young girl with carbidopa/levodopa suggests that this patient may have had underlying movement disorder which was unmasked by the peripheral injury.

Adolescent↗
PubMedDate not supplied

Tremor in Cree subjects exposed to methylmercury: a preliminary study.

Rest, postural, and kinetic tremors were recorded in Cree subjects (n = 36) exposed to low levels of methylmercury (MeHg) and control subjects (n = 30) using lasers designed to measure displacement. Displacement and derived velocity and acceleration time series were analyzed using quantitative characteristics in time and frequency domains. We found: 1) relatively low agreement between our results and those of a clinical examination done at the time of testing (r = 0.31 for postural tremor); 2) best discrimination with velocity of static (postural with visual feedback) and kinetic tremors for which significant differences between the two groups are found in many of the characteristics examined; 3) myoclonic-like finger microdisplacements in tremor of Cree subjects; 4) significant changes in static tremor of Cree subjects following a kinetic task; 5) significant differences among three age-matched subgroups of six subjects each (Cree with higher and lower MeHg level, and a control group) in characteristics that reflect difficulty with tracking, myoclonic-like microdisplacements and change in frequency composition of tremor after the tracking task. The subtle differences detected in this preliminary study suggest that further work is warranted to determine whether they can be unambiguously associated with exposure to MeHg.

Environmental Exposure↗
PubMed2002

Vibratory proprioceptive stimulation affects Parkinsonian tremor.

Previous research on tremor pathophysiology showed that tremor can be affected, e.g. by electrical stimulation of the peripheral nerve, mechanical perturbation of the limb and by transcranial magnetic stimulation of the motor cortex. This report is focused on possible effects of muscle vibration (MV) on resting tremor in Parkinson's Disease (PD). Vibratory stimulation was applied to the tendons of M. extensor carpi radialis longus and M. flexor ulnaris in 27 subjects with moderate PD resting tremor. The following effects were observed: (1) tremor stopped or started time-locked to MV onset and offset, (2) tremor persisted during MV but its frequency pattern changed. These results are discussed with specific emphasis to effects of MV on spinal and supraspinal levels.

Aged↗
PubMed2003

Abnormal gating of somatosensory inputs in essential tremor.

OBJECTIVE: To study whether sensorimotor cortical areas are involved in Essential Tremor (ET) generation. BACKGROUND: It has been suggested that sensorimotor cortical areas can play a role in ET generation. Therefore, we studied median nerve somatosensory evoked potentials (SEPs) in 10 patients with definite ET. METHODS: To distinguish SEP changes due to hand movements from those specifically related to central mechanisms of tremor, SEPs were recorded at rest, during postural tremor and during active and passive movement of the hand. Moreover, we recorded SEPs from 5 volunteers who mimicked hand tremor. The traces were further submitted to dipolar source analysis. RESULTS: Mimicked tremor in controls as well as active and passive hand movements in ET patients caused a marked attenuation of all scalp SEP components. These SEP changes can be explained by the interference between movement and somatosensory input ('gating' phenomenon). By contrast, SEPs during postural tremor in ET patients showed a reduction of N20, P22, N24 and P24 cortical SEP components, whereas the fronto-central N30 wave remained unaffected. CONCLUSIONS: Our findings suggest that in ET patients the physiological interference between movement and somatosensory input to the cortex is not effective on the N30 response. This finding thus indicates that a dysfunction of the cortical generator of the N30 response may play a role in the pathogenesis of ET.

Adult↗
PubMed2005

Drug-induced tremors.

Tremor is a common complaint for many patients. Caffeine and beta-adrenergic agonists are well-recognised drugs that cause or exacerbate tremors. Other tremorogenic drugs, such as selective serotonin reuptake inhibitors and tricyclic antidepressants, are less well recognised. Recognition of the drugs that can cause or exacerbate tremors can help prompt diagnosis, avoids unnecessary tests, and allows clinicians to quickly take corrective action (usually by discontinuing the tremor-inducing drugs). The aim of this review is to provide clinicians with current information on drugs that are associated with tremor and the correct treatment of these drug-induced tremors.

Adrenergic beta-Agonists↗
PubMed1999

Historical and clinical features of psychogenic tremor: a review of 70 cases.

OBJECTIVES: To review the clinical characteristics and associated features found in patients with psychogenic tremor. METHODS: Ten-year retrospective review of charts of all patients and videotapes of fifty-one patients diagnosed by the senior author as having psychogenic tremor. RESULTS: Seventy patients fulfilled the diagnostic criteria for clinically definite psychogenic tremors. Psychogenic tremors usually started abruptly (73%), often with the maximal disability at onset (46%), and then took static (46%) or fluctuating (17%) courses. Psychogenic tremors usually started in one limb and spread rapidly to a generalized or mixed distribution. Spontaneous resolution and recurrence, easy distractibility together with entrainment and response to suggestion were characteristic features. Presence of functional symptoms and signs and refractoriness to conventional antitremor drugs were common. CONCLUSIONS: Psychogenic tremor is generally not a diagnosis of exclusion. The presence of characteristic features on history and especially clinical examination can permit an accurate diagnosis and avoid unnecessary investigations.

Adolescent↗
PubMed1999

Dynamics of tremor-related oscillations in the human globus pallidus: a single case study.

Physiological evidence indicates that the resting tremor of Parkinson's disease originates in oscillatory neural activity in the forebrain, but it is unknown whether that activity is globally synchronized or consists of parallel, independently oscillating circuits. In the present study, we used dual microelectrodes to record tremor-related neuronal activity from eight sites in the internal segment of the globus pallidus (GPi) from an awake Parkinson's disease patient undergoing stereotaxic pallidotomy. We utilized spectral analysis to evaluate the temporal correlations between multiunit activity at spatially separated sites and between neural and limb electromyographic activity. We observed that some GPi neural pairs oscillated synchronously at the tremor frequency, whereas other neural pairs oscillated independently. Additionally, we found that GPi tremor-related activity at a given site could fluctuate between states of synchronization and independence with respect to upper limb tremor. Consistent with this finding, some paired recording sites within GPi showed periods of transient synchronization. These observations support the hypothesis of independent tremor-generating circuits whose coupling can fluctuate over time.

Brain Mapping↗
PubMed1986

A new tremor balance-transducer.

A new tremor-measuring device has been developed. It is constructed as a beam balance and measures principally in a vertical direction. Both arms of the beam contain a ceramic crystal; one of the arms has an extension that rests on the object to be measured. In this way, problems associated with mounting the transducer to the object are eliminated. The balance-transducer performs a well defined rotational movement in contrast to the frequently used transducers with a single sensor which are mounted to the object. The tremor movement of the limb and/or inadequate mounting causes unknown variation in the influence of the gravity component on the sensor; this can cause substantial errors. This tremor-transducer eliminates this problem. The static load of the balance-transducer on the object can be adjusted to less than 0.5 X 10(-3) kg(0.005 N). Even in the case of finger tremor, the balance-transducer does not influence the tremor phenomenon significantly. The principle of the balance-transducer is suited to measurements of postural, intention and limited action tremor of the finger, hand, forearm and jaw.

Biomechanical Phenomena↗
PubMed2001

A dissociation between subjective and objective unsteadiness in primary orthostatic tremor.

Patients with primary orthostatic tremor (OT) experience a disabling sense of unsteadiness but rarely fall. In order to study the relationship between the development of subjective unsteadiness, objective unsteadiness and tremor, we recorded standing under four conditions (eyes open or closed, feet together or apart) in six patients with OT. Subjective unsteadiness was indicated by the patients on a four-point scale using a hand-held slider. Objective unsteadiness was assessed by measuring the path lengths of the centre of foot pressure and body motion at the level of the cervical spine. Tremor was measured by surface electromyography from leg and paraspinal muscles. OT patients were objectively more unsteady than controls. Objective unsteadiness also increased disproportionately in patients when standing with eyes closed. These findings suggest that balance control in OT is abnormal and shows increased visual dependence. Subjective unsteadiness increased from mild to severe over seconds to minutes. The increase was faster when standing with eyes closed or feet together. However, although escalating subjective unsteadiness was paralleled by an increase in leg tremor, there were no comparable changes in either paraspinal tremor or objective unsteadiness during the course of a stand. We conclude that there is a dissociation between subjective and objective unsteadiness. This implies that subjective unsteadiness does not arise simply from an awareness of increased body sway. We postulate that the sensation of unsteadiness arises from a tremulous disruption of proprioceptive afferent activity from the legs. This disturbance gives rise to increased co-contracting drive to the leg muscles in order to stiffen the joints and increase stability. Since muscle activity remains tremor-locked, the tremulous proprioceptive feedback is increased, which then further increases the sensation of unsteadiness, and so on in a vicious circle of escalating activity.

Aged↗
PubMed2002

Influence of proprioceptive input on parkinsonian tremor.

Previous studies have shown a modification of parkinsonian tremor (PT) by proprioceptive input induced by passive joint movements. The authors investigated the impact of electrically evoked proprioceptive input on PT. In eight patients with PT they recorded surface EMG from the opponens pollicis muscle, and forearm extensors and flexors. Rhythmic electrical stimulation was applied to the ipsilateral median nerve at the wrist using a submaximal stimulus intensity and stimulus frequencies between two stimuli per second and five stimuli per second. The tremor frequency did not adapt to the stimulus frequency. Tremor frequency of parkinsonian resting tremor increased significantly in the directly stimulated opponens pollicis muscle (mean +/- standard deviation, 4.35 +/- 0.64 Hz without stimulation versus 4.53 +/- 0.68 Hz with stimulation; P < 0.05, paired t-test), the not directly stimulated forearm muscles (4.90 +/- 0.72 Hz versus 5.18 +/- 0.73 Hz, P < 0.001), and the upper arm muscles (5.13 +/- 0.61 Hz versus 5.36 +/- 0.68 Hz, P < 0.01). Furthermore, the parkinsonian postural tremor accelerated significantly during ipsilateral median nerve stimulation (5.31 +/- 0.99 Hz versus 5.44 +/- 1.03 Hz, P < 0.05). Parkinsonian resting tremor in the forearm muscles also accelerated significantly during ipsilateral ulnar nerve stimulation (4.85 +/- 0.57 Hz versus 5.05 +/- 0.65 Hz, P < 0.05). Contralateral median nerve stimulation had no significant effect. These results suggest a close interaction between proprioceptive input and PT generation.

Adult↗
PubMedDate not supplied

Genetic heterogeneity in autosomal dominant essential tremor.

PURPOSE: To perform linkage analysis of candidate loci in a large Midwestern family with autosomal dominant essential tremor. METHODS: Thirty-eight members of a six-generation family were evaluated for essential tremor using consensus criteria. Linkage analysis was performed with microsatellite markers reported for three genetic loci associated with familial essential tremor. RESULTS: Patients exhibited a combination of postural and kinetic tremor involving primarily the arms and hands, with a mean age of onset of 31 years. Genetic studies excluded linkage to ETM1 and ETM2 loci, as well as a candidate locus for parkinsonism and postural tremor on chromosome 4p. CONCLUSION: Familial essential tremor is a common hereditary movement disorder demonstrating phenotypic variability and genetic heterogeneity.

Adult↗
PubMed1991

Tremor.

Tremor is a rhythmic, involuntary muscular contraction with consistency of rate, amplitude and pattern. It is the most common of all involuntary movements. Several systems for classifying tremor exist with the most frequent system classed according to behavioral context, ie, resting, postural and action. Clinical recognition of tremor type is extremely important as type determines prognosis, treatment and need for genetic counseling. The most common forms are parkinsonian, physiological, cerebellar intention and essential tremor. Essential or hereditary tremor is the most common of all neurologic conditions with 3-4 million Americans affected. Nursing implications of caring for essential tremor patients are presented.

Adrenergic beta-Antagonists↗
PubMed2002

Higher order statistics and neural network for tremor recognition.

This paper is concerned with the tremor characterization for the purpose of recognition. Three different types of tremor are considered in this paper: the parkinsonian, essential, and physiological. It has been proven that standard second-order statistical description of tremor is not sufficient to distinguish between these three types. Higher order polyspectra based on third- and fourth-order cumulants have been proposed as the additional characterization of the tremor time series. The set of 30 quantities based on the polyspectra has been proposed and investigated as the features for the recognition of tremor. The neural network of the multilayer perceptron structure has been used as a classifier. The results of numerical experiments have proven high efficiency of the proposed approach. The average error of recognition of three types of tremor did not exceed 3%.

Computer Simulation↗
PubMed1984

Effect on finger tremor of withdrawal of long-term treatment with propranolol or atenolol.

The effect of the withdrawal of long-term beta-adrenoceptor blockade on pulse rate and finger tremor was studied in 27 patients who had been treated for 2 years following an uncomplicated myocardial infarction with either atenolol, propranolol or placebo. During treatment, pulse rate was significantly lower in patients treated with propranolol or atenolol compared with placebo. Compared with the response in the placebo group the mean increase in tremor on withdrawal of propranolol was statistically significant for postural and for work tremor in both hands. A significant increase in tremor on withdrawal of atenolol occurred only in the postural position and in a narrow frequency band (left hand, 7-11 Hz; right hand, 7-9 Hz). The differences in the effect on tremor of withdrawal of treatment with propranolol or atenolol in doses which produced similar reductions in heart rate, emphasise the beta 2 classification of peripheral receptors associated with normal muscle tremor but do not exclude the involvement of beta 1-adrenoceptors.

Atenolol↗
PubMed1989

Propranolol, clonidine, urapidil and trazodone infusion in essential tremor: a double-blind crossover trial.

Accelerometric tremorgrams were recorded from 25 subjects affected by essential tremor and analysed by a Berg-Fourier frequency analyser before and during venous infusion of the following drugs: propranolol (beta-blocker), clonidine (alpha-presynaptic adrenergic agonist), urapidil (alpha-postsynaptic blocker), trazodone (adrenolytic agent) and placebo. The washout interval between infusions was 3 days. Recordings and data analyses were performed in a double-blind crossover trial. Tremor was classified as: at rest; postural (arms hyperextended); and intention (finger-nose test). Analysis of the results showed that propranolol and clonidine reduced significantly (P = 0.01 and P = 0.009, respectively) the power spectrum of postural tremor, but left at rest and intention tremors unchanged. No significant effects on the tremor power spectrum were observed after placebo, urapidil or trazodone administration. None of the drugs had any effect on tremor frequency.

Adult↗
PubMed1980

Comparison of electromyogram spectra with force spectra during human elbow tremor.

1. The tremor that develops when the elbow is flexed against a spring attached at the wrist has been analysed by determining the 'power' spectrum of the demodulated surface e.m.g. recorded from two of the active muscles, biceps and brachioradialis. This was compared with the corresponding force spectrum obtained by analysis of the force developed at the fixed end of the spring (normally one of stiffness 2.8 N/mm); this force is directly proportional to the movement at the wrist. 2. When the subject was maintaining a high target force (100-160 N), with the aid of a visual display, the tremor was large with a large sharply tuned peak in the force spectrum and there was a clear peak at the same frequency in the e.m.g. spectrum. The coherence (gamma) between the force peak and the corresponding e.m.g. peak typically had a value of 0.95 or above, indicating a high degree of correlation. 3. On developing the same target force against a rigid restraint (70 N/mm) the peak in the force spectrum was absent or very much smaller and less sharply tuned. More particularly, the tremor-related peak seen in the e.m.g. spectrum under compliant conditions was no longer present under rigid conditions. 4. At low target forces (20-40 N) with compliant loading there was a small peak in the force spectrum but no peak could be detected in the e.m.g. spectrum. With increasing target force the mechanical tremor increased considerably and a peak progressively emerged from above the background level in the e.m.g. spectrum, accompanied by the development of a corresponding peak in the coherence spectrum. Thus the difference in detectability of peaks in the e.m.g. and force spectra might simply result from differences in the background 'noise' level of the two types of spectra. 5. Changing the spring stiffness in the range 0.7-12.5 N/mm altered the frequency of the mechanically recorded tremor by 1.5-2 Hz and the peak in the e.m.g. spectrum shifted in approximate correspondence. 6. The findings support the view that the tremor seen with compliant loading of the arm is due to the stretch reflex. In addition, this work should help define the conditions under which spectral analysis of the gross e.m.g. is of practical utility.

Adolescent↗
PubMed1983

Predictions of the existence, frequency, and amplitude of physiological tremor in normal man based on measured frequency-response characteristics.

Mathematical models for 1) musculoskeletal dynamics, and 2) reflex feedback, based on the results of the authors' frequency-response measurements on normal adult male human subjects, are combined to produce a model for physiological tremor in such subjects. An analysis of this model shows that the system will be unstable to small disturbances (that is, tremor will occur) under certain conditions of external loading. Further, when the system is unstable, nonlinearities in the model produce responses in the form of limit cycles, and both the frequency and amplitude of the resulting tremor can be calculated. For constant loads applied through a constant compliance, the model predicts the onset of tremor at low loads, a maximum intensity of tremor at loads corresponding to 30-50 percent of maximum voluntary effort, and a decrease in the tremor amplitude at still higher loads.

Biomechanical Phenomena↗
PubMed2000

Limb stiffness and postural tremor in the arm.

The relation between limb stiffness and postural tremor in the upper arm was investigated during a pointing task. The task goal was to minimize the amount of motion (tremor) at the index finger under levels of increasing limb stiffness. This study investigated the influence of increasing limb stiffness on the pattern of intra- and interlimb dynamics. The frequency profile of the tremor for all limb segments across all conditions displayed two peaks, one between 2-4 Hz and another between 8-12 Hz. A third, higher frequency component (20-22 Hz) was present in the index finger. Increasing limb stiffness through voluntary co-contraction of antagonistic muscle pairs effectively constrained the segments of the upper limb to increasingly operate as a single biomechanical degree of freedom. Higher levels of limb stiffness typically led to an increase in the frequency and power of the 2-4 and 8-12 Hz peaks. There was also a decrease in the frequency of the 20-22 Hz component of finger tremor. The act of reducing the effective degrees of freedom in joint space through voluntarily stiffening of the upper limbs also resulted in decreased performance as determined by an increase in finger tremor. In the preferred, natural level of limb stiffness, specific intralimb segment relations were observed but there was no significant interlimb coupling. The intralimb segment correlations were characterized by compensatory (out of phase) coupling between the upper arm/forearm and hand/index finger segment pairs of each limb that were organized about the action of the wrist joint. Increasing the degree of limb stiffness led to a decrease in the level of intralimb coupling. The findings suggest that the most efficient mechanism for reducing tremor at the periphery is that of compensatory coupling between relevant intralimb segments with a low level of limb stiffness.

Adult↗