Different Types Of Tremor Research Articles

Instrumentation notes - Mathematical approach to tremor recognition in extrapyramidal disease

Tremor is rhythmic involuntary oscillatory movement of body parts. There have been attempts to separate tremors due to different extrapyramidal diseases with objective techniques by measuring the acceleration of hands and applying the features of conventional spectral description, peak value and peak frequency of power spectral density (PSD). However, no clear-cut separation has been found with these methods; none of the parameters helps to decide reliably which kind of pathological tremor is present. The task is then twofold: to exploit other PSD features and to apply descriptions extracting new information from existing data. This article shows that the features of this process, based on the application of cumulants and polyspectra, represent different types of tremor and may stand as the basis for recognition between them. The results of numerical experiments are presented and discussed.

Clinical aspects of Parkinson disease

Parkinson disease is a slowly progressive neurodegenerative disorder with a varied clinical picture and a variable rate of progression. Recently, there have been some studies conducted to assess the diagnostic accuracy and other clinical aspects of the disease. In the absence of a biomarker the clinical diagnosis is imprecise. This leads to a significant number of misdiagnoses, especially in early disease. Assessment of the clinical features suggests that an accuracy of 90% may be the highest that can be expected using current diagnostic criteria. In addition to bradykinesia, which is a core symptom, different types of tremors occur. Whereas the rest tremor is characteristic, action tremor, re-emergent tremor and orthostatic tremor may occur in Parkinson disease. Symptomatic treatments are quite effective in early disease but clinical course is complicated by the appearance of motor fluctuations and dyskinesias in more advanced disease. Non-motor complications, such as cognitive, psychiatric and autonomic problems, become bothersome and disabling in some patients.

Clinical aspects of Parkinson disease.

Parkinson disease is a slowly progressive neurodegenerative disorder with a varied clinical picture and a variable rate of progression. Recently, there have been some studies conducted to assess the diagnostic accuracy and other clinical aspects of the disease. In the absence of a biomarker the clinical diagnosis is imprecise. This leads to a significant number of misdiagnoses, especially in early disease. Assessment of the clinical features suggests that an accuracy of 90% may be the highest that can be expected using current diagnostic criteria. In addition to bradykinesia, which is a core symptom, different types of tremors occur. Whereas the rest tremor is characteristic, action tremor, re-emergent tremor and orthostatic tremor may occur in Parkinson disease. Symptomatic treatments are quite effective in early disease but clinical course is complicated by the appearance of motor fluctuations and dyskinesias in more advanced disease. Non-motor complications, such as cognitive, psychiatric and autonomic problems, become bothersome and disabling in some patients.

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%.

Electromyographic differentiation of tremors

Objective: The aim of this study was to explore the opportunity for differentiation of tremors on the basis of the electromyographic examination. Methods: We report data from 525 patients with different types of tremor included in this study. Two hundred and twenty patients with essential tremor, 110 patients with Parkinson's disease, 24 patients with midbrain tremor, 22 patients with cerebellar tremor, 120 patients with enhanced physiological tremor due to anxiety, and 29 patients with psychogenic tremor participated in the study. A detailed neurological and electromyographic examination was performed. The tremor was studied in all limbs positions. Surface electromyographic recordings of the most involved body part were performed to all patients. Results: According to the electromyographic examination all patients were divided to two groups: Patients with synchronous tremor and patients with alternating tremor in the antagonist muscles. The comparisons were performed only between the patients with tremor caused by different etiology within the group of synchronous or alternating tremor. The group of tremors with synchronous pattern included the patients with essential tremor type A (with synchronous activity), cerebellar, and enhanced physiological tremor. The group of tremors with alternating pattern included patients with Parkinsonian tremor, essential tremor type B (with alternating activity), rubral, and psychogenic tremors. Our results revealed that electromyographic examination of tremor pattern, frequency, amplitude, and burst duration is useful for tremor differentiation. Conclusion: The electromyographic examination may serve as a tool for differentiation of tremors.

A cross-over clinical and electromyographic assessment of treatment for parkinsonian tremor

Background: Whether dopaminergic and anticholinergic drugs exert influence on parkinsonian rest and postural tremor is a subject of debate. Different types of tremor may be influenced differently by the drugs. The aim of this study was to reevaluate the differential effects of levodopa and anticholinergic drugs on parkinsonian tremor in different limb positions and on different types of postural tremor. Methods: Thirty-eight patients with parkinsonian resting tremor and postural tremor were included in this study. Patients were divided into two groups according to the electromyographic pattern of the postural tremor. We found fast synchronous postural tremor (>7 Hz) in 16 patients, and slow alternating postural tremor in 22 patients. The tremor was scored clinically in each limb position using the Webster Tremor Scale. Surface electromyographic recordings from the most involved limb in all positions were also performed. The patients were randomly assigned to levodopa (one 250/50-mg tablet), or to biperiden (one 3-mg tablet). Tremor was assessed by clinical and electromyographic examinations at base line 1 h following ingestion of the drug. The subjective tremor improvement was also assessed. Results: We found that levodopa had a good effect on the amplitude of the resting tremor, while the effect of biperiden was weaker. Both levodopa and biperiden has less effect on postural tremor. However, levodopa's effect was better than that of biperiden. Levodopa and biperiden had better effect on slow alternating postural tremor than on fast synchronous postural tremor. They had no effect on kinetic and intention tremors. Conclusions: Levodopa and anticholinergic drugs have differing effects on both resting and postural tremor Also, the different categories of postural tremor respond differently to treatment. The mechanisms underlying resting parkinsonian tremor may be different from those underlying postural, kinetic and intention tremor. Moreover, the mechanisms underlying different types of postural tremor may be different.

Clinical and electromyographic examinations of Parkinsonian tremor.

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.

Classification of normal and pathological tremors using a multidimensional electromagnetic system

A new multidimensional movement analysis system was used to record limb tremor over six degrees-of-freedom, and signal processing techniques were explored to develop a suitable classification method to distinguish between different types of tremor. The specific aims were to investigate the ability of the system to screen for differences between normal subjects and a group of neurological patients, and then to differentiate between three diagnostic groups of patients. Postural tremor at the hand was recorded in normal subjects ( n=24) and patients with essential tremor ( n=21), multiple sclerosis ( n=17) and parkinsonism ( n=19). Data were collected using a 3Space Fastrak ® (Polhemus, Inc.) over six degrees-of-freedom (three translational directions and three rotations). Spectral estimates produced measures of tremor frequency and amplitude. Mathematical models of the data, using autoregressive modelling and K-nearest neighbour classification, produced parameters used to classify, (1) the normal subjects and 24 patients (using the three rotational movements), and (2) the three patient groups (using all six movement directions). Results were given in terms of the probability of each subject belonging to the groups being classified. Tremor frequency and amplitude showed large overlap between the groups. The screening classification produced high probabilities of correctly classifying normal subjects (>70%) and patients (>70%). The diagnostic classification produced clear differences between the patient groups (60% for essential tremor, 80% for multiple sclerosis and 60% for parkinsonism). The ability of this assessment technique to distinguish between postural tremor in normal subjects and neurological patients suggests that it could be developed as a screening tool. Classification of tremors between the patients groups, with a high degree of sensitivity, indicates the potential for further development of the system as a diagnostic aid.

Clinical neurophysiology of tremor.

The neurophysiological analysis of tremor has a long tradition. These attempts were directed to understand the mechanisms underlying tremor, on the one hand, and to develop tools to better diagnose the different types of tremor, on the other. Meanwhile, reasonable criteria are available to distinguish between centrally and peripherally mediated tremors. However, no generally accepted means exist to differentiate the different forms of central tremors. Frequency is a useful classifier for cerebellar tremor, rubral tremor, and orthostatic tremor. Although the highest amplitudes are found in Parkinson's disease, this parameter does not well distinguish between the different tremors. Waveform analysis of tremor is a promising tool to separate between the different tremors. Polymyography is pathognomonic for some rare forms of tremor. New approaches to classify tremors are based on positron emission tomography scanning, analysis of ballistic movement, and reflex testing. The means to separate myoclonias from tremors include EEG/EMG correlation techniques, long-latency reflexes, and polymyography. Provided these techniques are applied in the setting of careful clinical analysis of tremor syndromes, they may prove to be helpful in clinical practice.

Different types of tremor in the human thumb.

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.

Pindolol-induced tremor

Five patients were treated with pindolol for various indications. The patients called attention to the appearance of fine tremors in their extremities 6-72 hr after starting treatment with the drug. The tremors disappeared 24-72 hr after stopping the drug. Beta-adrenoceptor-blockers are known to suppress different types of tremor and the paradoxical appearance of tremors during pindolol treatment is attributed to its powerful partial agonist activity. To the best of the authors' knowledge this side effect has not been previously described in the literature.

Importance of microstereoencephalotomy for tremor alleviation.

Application of the microelectrode technique in human stereotactic surgery, which is especially important for tremor control, is now routine for the procedure in our surgical theater. Neurons responsible for tremor generation can very delicately and exactly be identified within the ventralis intermedius nucleus (Vim) of the thalamus, which automatically determines the location of the minimum required thermocoagulation lesion to abolish tremor. Neurons with rhythmic burst discharges, which are synchronus in phase to the peripheral tremor, are organized in delicate somatotopic fashion within the Vim. Electrical stimulation of the neuron area through this microelectrode usually inhibits tremor of the corresponding area and a small thermocoagulation lesion, usually 3 mm in diameter, permanently abolishes tremor. These three findings, i.e., existence of rhythmic bursts, effect of the stimulation and surgical lesion, are the same in parkinsonian tremor, postural tremor and intention tremor. Physiological interpretation of different types of tremor will be proposed. In the cases of idiopathic neck tremor, a single Vim neuron corresponded to four neck muscles, i.e., bilateral sternocleidomastoid muscle (SCM) and bilateral posterior neck muscles, and most markedly to the controlateral posterior neck muscle and the ipsilateral SCM. Instrumentation of microstereoencephalotomy is also explained.

Tremor studies in normals and in Parkinsonism.

I. Introduction This study is devoted to the symptom of tremor which has been utilized by some to indicate the gross rhythmic oscillatory movement of the limbs in parkinsonism. Others use the word tremulousness to apply to the fine, irregular oscillations in the extremities of patients with such diseases as thyrotoxicosis or alcoholism. For the purposes of this study, tremor is a descriptive term to designate any oscillatory movement of a part of the body which is activated by skeletal muscle, be it regular or irregular, fine or gross, constant or periodic, present at rest or on actvity. It is true that different types of tremor exist, depending upon many factors, ranging from disease process to the position of the oscillating part. These factors, in relation to the normal and to the patient with parkinsonism, will be discussed. The purpose of this study is threefold. First, we desire to establish

Tremor following explosions.

Discusses the organic vs psychogenic etiology of tremors following explosions, and their diagnosis and treatment. Clinical analyses of 2 cases are presented, which point to the emotional origins of the disorder. In establishing the psychological basis of such tremors, a mental examination is necessary. Even in the absence of ascertainable hysteria, the emotional origin can be confirmed by the ability of the emotional shock to provoke or exaggerate the tremors. Tremors of organic origin can be induced by adrenalin injections, insular sclerosis, and dysergia. Specific treatment methods for different types of tremors are elaborated. (PsycINFO Database Record (c) 2006 APA, all rights reserved)