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

The effect of "task relevance" on early and late components of cortical and subcortical somatic evoked potentials (SEPs) was studied in a group of Parkinsonian patients operated on under local anesthesia for treatment of prominent unilateral tremor. 1. SEPs produced by median nerve stimulation were found at contralateral cortical (ss), thalamic (vcpci, vcai), lemniscal (Lm), postilemniscal (PoLm), prelemniscal (Raprl) and reticular (Ttc) regions. No SEPs were found in other contiguous thalamic (M,Pf, ce) and subthalamic (Q) regions. 2. Subcortical early SEP components consisted of two monophasic positive potentials distributed within a circumscribed thalamo-lemniscal region where electrical stimulation elicited consistent sensory responses circumscribed to contralateral hand and face. In contrast, subcortical late SEP components consisted of monophasic or polyphasic, positive or negative potentials distributed in a widespread, thalamic, lemniscal, prelemniscal and reticular region where elecrical stimulation elecited sensory or motor responses of various types. Subcortical early and late SEP components appeared together in lemniscal, thalamic and cortical regions but they wers separated at postlemniscal (only early) and prelemniscal and reticular ones (only late). 3. Significant amplitude changes in cortical and subcortical late SEP componets were found concomitant to variations in "task relevance": they decreased when patients shifted from novelty to habituation, they increased when patients shifted from habituation to attention and they decreased when patients shifted from attention to distraction. In contrast, no significant ampiltude changes in cortical and subcortical early components were found when patients shifted through these various "task relevance" conditions.
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PMID:Differential effect of task relevance on early and late components of cortical and subcortical somatic evoked potentials in man. 5 18

Tremors in post-traumatic stress disorders have not been previously well characterized. A 67-year-old man has a 46-year history of a noise-induced exaggerated startle reflex followed by a large amplitude rest, postural and kinetic tremor that may persist for up to 3 days. This tremor is superimposed on a continuous mild organic postural/kinetic tremor whose electrophysiological characteristics are different from those of the overlying tremor. We attribute the exaggerated startle reflex and the noise-induced tremor to Post-Traumatic Stress Disorder (PTSD) and postulate a psychogenic origin for the noise-induced tremor. The patient also believes the noise-induced tremor to be psychologically based and to be produced by the fear and anxiety he experiences when he hears loud, unexpected noises. The sudden onset of the noise-induced tremor, its intermittent character, its temporary disappearance on distraction despite the patient's inability to suppress it, inconsistencies in handwriting and figure drawing, and the fact that the noise-induced tremor is stimulus specific and persists long after the offending stimulus (noise) is no longer present all suggest a tremor of psychogenic origin.
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PMID:Noise-induced psychogenic tremor associated with post-traumatic stress disorder. 148 27

Tardive dyskinesia (TD) is a consequence of chronic neuroleptic therapy. It is an irregular stereotyped movement disorder that is usually choreic in appearance, and is subject to temporary volitional control. Dystonia, akathisia, and tics are uncommon variants of the classic tardive syndrome. Characteristic clinical features including amelioration by action, augementation by distraction, partial volitional suppressibility, and lack of subjective distress help differentiate TD from other movement disorders such as resting tremor, Huntington's disease, spontaneous dyskinesias, and abnormal movements accompanying psychiatric illnesses.
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PMID:Recognition and differential diagnosis of tardive dyskinesia. 257 70

There are few studies analyzing the incidence, clinical characteristics and diagnostic work-up of psychogenic tremor. We studied the clinical and electrophysiological characteristics and the associated psychopathology in a series of patients with psychogenic tremor. All patients (n = 8) diagnosed with documented or clinically established psychogenic tremor in the movement disorders section of our Department of Neurology in a two-years period were analysed. Psychogenic tremor was diagnosed in 9.5% of the patients that consulted for postural or action tremor of the upper limbs. In all cases tremor had a variable frequency and amplitude and improvement with distraction. Electrophysiological studies revealed asynchronic muscle activity and considerable variation of the dominant frequency when weight was added to the patient hands. Six patients were initially misdiagnosed of essential tremor (n = 3); Parkinson's disease (n = 1); and cerebrovascular disease (n = 2). Final psychiatric diagnoses were depression (n = 4); conversive disorder (n = 2); and malignering (n = 2). Psychogenic tremor is a relatively frequent cause of tremor in a Movement Disorders Clinic and has a characteristic clinical and electrophysiological pattern.
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PMID:[Psychogenic tremor: clinical, electrophysiologic and psychopathologic assessment]. 943 98

In a total of 30 tremor patients (14 with Parkinson's disease, 6 with cerebellar tremor, 4 with essential tremor, 4 with psychogenic tremor, 2 with enhanced physiological tremor), tremor was electromyographically recorded before, during and after contralateral distraction tasks (tapping with the index finger or the tip of the foot, sequential flexion of the 2nd to 5th finger towards the thumb, "keyboarding", and sensory discrimination). 22 of 26 patients with organic tremors spontaneously choose a volitional tapping frequency independent from their tremor frequency. In 4 patients with psychogenic tremor, frequencies of tremor and tapping were locked (n = 3), or tremor disappeared abruptly (n = 1) when contralateral tapping was started. Contralateral "keyboarding" and sensory discrimination revealed no clear differences between organic and psychogenic tremors. Contralateral tapping in further 23 patients (22 with organic tremors and 1 with psychogenic tremor) confirmed these findings. Contralateral tapping appears as the most valid distraction task and may help to differentiate psychogenic from organic tremors.
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PMID:[Polygraphic validation of distraction tasks in clinical differential tremor diagnosis]. 983 78

Tremor is frequently encountered in neurologic practice. Clinical examination supplies information regarding its approximative frequency, regularity, amplitude, topography and activation conditions. The neurophysiological study helps in confirming the tremor, in differentiating it from other movement disorders like myoclonus, and may provide distinctive features which are important for the aetiological diagnosis. The neurophysiological investigation includes accelerometry, which analyses the mechanics of the movement. Spectral analysis with FFT allows the determination of frequency and amplitude. Accelerometry is always associated with surface EMG of at least two antagonistic muscles. It may show rhythmic bursts, their frequency, duration and activation pattern (alternating or synchronous). This neurophysiological approach to tremor has multiple interests. It may help in differentiating a true rest tremor from a postural tremor seemingly persisting at rest. Brief interruptions or rhythm breaks during distraction manoeuvers are seen in psychogenic tremors. Surface EMG may also demonstrate positive myoclonic bursts, or brief silent periods corresponding to negative myoclonus, sometimes pseudorhythmic, thus appearing clinically like a tremor, but investigations, aetiologies and treatment are different. Several features, especially slow frequency, may suggest a midbrain tremor, thus requiring brain imagery centered around the posterior fossa. Finally, the neurophysiological examination is the only way to demonstrate a primary writing tremor, or a primary orthostatic tremor, the frequency of which is pathognomonic while clinical symptoms are rather misleading.
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PMID:[Neurophysiologic study of tremor]. 1081 77

Movement disorders have rarely been the result of psychiatric disturbances. Psychogenic dystonia is caracterized by inconsistent findings, a known precipitant factor, onset in legs, pain, multiple somatizations and incongruent association with other movement disorders. We report two patients with clinically established psychogenic dystonia. Patient 1: a female that presented sudden loss of strength in her four limbs; she developed feet dystonia, alternant laterocollis, generalized and irregular tremor, and limb hypertonia that disappeared with distraction; psychological examination showed severe depression, hypochondria and obsessive disorder. Patient 2: a female that presented with irregular limb tremors that disappeared with distraction and left foot dystonia nine years ago; she gradually lost her walk capacity; she complained pain in lumbar area and in her left limb, psychological examination showed infantile behaviour, low frustration tolerance, impulsivity and self-aggression. Their complementary exams showed no alterations and they had no response to specific pharmacological treatment. Dystonia is rarely psychogenic, but this etiology is suggested when clinical characteristics are inconsistent and incongrous with a classical disorder. It should be part of differential diagnosis when appears in association with other somatization or psychiatric disorders.
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PMID:[Psychogenic dystonia: report of 2 cases]. 1092 Apr 17

Monitoring systems enable the long-term registration of tremor in patients with Parkinson's disease This method is useful in the objective measurement of tremor during the course of treatments. Indeed, the symptoms of tremor as well as the aggravating and attenuating influences can be observed under real-life conditions. The methodology of data recording and analysis, described in previous investigations, was extended to automatically detect body position and certain movement patterns with calibrated 4-channel accelerometry. The main purpose of the present investigation was to apply this refined and extended methodology to patients in a clinical rehabilitation program, and to examine its practability with respect to the results of the treatment and the patients' compliance. The methodology was tested on 30 patients (17 male, 13 female) with Parkinson's disease. The mean age was 64.8 years (s = 8.9). The Hoehn-Yahr index ranged from 1 to 3 (m = 2.3, s = 0.7) and the overall UPDRS scale between 10 and 74 (m = 42.9, s = 18.1). The data recording included: (1) the registration of tremor under standardised conditions of rest and postural tremor test with and without distraction; (2) a standard protocol to obtain reference values for body position and movement; and (3) the 24-hr monitoring. 21 patients could be recorded a second time, on average 18 days after the first recording. Between the two registrations, patients received individually tailored drug treatment supplemented with specific activating physiotherapy, ergotherapy measures, and individual psychotherapeutic counseling. Changes between first and second recording were evident for the three tremor variables, but significant only for the 24-hr ambulatory monitoring. The between and within-subjects correlations of the tremor variables were rather low except the correlations between occurrence and amplitude (between-subjects. 87; within-subjects. 67). Conditions of rest and postural tremor test showed a correlation with corresponding segments of the ambulatory monitoring of about. 50 for the tremor occurrence. The best prediction of the day-time monitoring was made by the tremor tests with distraction, whereas the night segment was best predicted by the standard protocol.
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PMID:Tremor in Parkinson's disease: 24-hr monitoring with calibrated accelerometry. 1512 53

In contrast to essential tremor (ET), psychogenic tremor (PT) is often manifested by shaking with variable amplitude and frequency, distractibility, suggestibility, and entrainment. The sensitivity and specificity of these findings in differentiating PT and ET have not been systematically examined. In order to determine clinical features that reliably distinguish PT from ET, we collected patient information regarding tremor onset, spontaneous remissions, family history, and employment history. A "blinded" rater evaluated video segments of subjects using a standardized protocol with special attention to distractibility, suggestibility, or entrainment. A total of 45 subjects with ET or PT were enrolled in this study: 33 met clinical criteria for ET with a mean age of 56.8+/-17.0 years and 12 met clinical criteria for PT with a mean age of 42.5+/-11.0 years. PT subjects were significantly more likely to relay a history of sudden onset (p=0.03), spontaneous remissions (p=0.03), and shorter duration of tremor (p=0.001). Family history of tremor was significantly more common in the ET group (p=0.001). A moderate-to-marked degree of distraction with alternate finger tapping (p=0.01) and mental concentration on serial 7 s (p=0.01) was more common in PT. Furthermore, suggestibility with a tuning fork (p=0.04) and exacerbation with hyperventilation (p=0.06) seemed predictive of PT. Entrainment was not different in the two groups. In conclusion, a history of tremor with sudden onset and spontaneous remissions along with distractibility and suggestibility on examination are good predictors of PT and help differentiate it from ET.
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PMID:Distinguishing psychogenic and essential tremor. 1760 55

Tremor, an involuntary, rhythmic, oscillatory movement of a body part, is the most common movement disorder encountered in clinical practice. Rest tremors occur in a body part that is relaxed and completely supported against gravity. Action tremors occur with voluntary contraction of a muscle and can be further subdivided into postural, isometric, and kinetic tremors. All persons have low-amplitude, high-frequency physiologic tremors at rest and during action that are not reported as symptomatic. The most common pathologic tremor is essential tremor. In one-half of cases, it is transmitted in an autosomal dominant fashion, and it affects 0.4 to 6 percent of the population. More than 70 percent of patients with Parkinson disease have tremor as the presenting feature. This tremor is typically asymmetric, occurs at rest, and becomes less prominent with voluntary movement. Features consistent with psychogenic tremor are abrupt onset, spontaneous remission, changing tremor characteristics, and extinction with distraction. Other types of tremor are cerebellar, dystonic, drug- or metabolic-induced, and orthostatic. The first step in the evaluation of a patient with tremor is to categorize the tremor based on its activation condition, topographic distribution, and frequency. The diagnosis of tremor is based on clinical information obtained from a thorough history and physical examination. For particularly difficult cases, single-photon emission computed tomography to visualize the integrity of the dopaminergic pathways in the brain may be useful to diagnose Parkinson disease.
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PMID:Differentiation and diagnosis of tremor. 2140 80


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