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PubMed2004

[Differentiation of parkinsonian and essential tremor using electrophysiological methods].

OBJECTIVE: Tremor is one of the most common movement disorders. Different tremors are induced by central and/or peripheral oscillators. The motor cortex plays a significant role in the generation of parkinsonian tremor but its function in essential tremor is not clear. We examined the effect of motor cortex activation on parkinsonian and essential tremor during movement of the contralateral hand. Our aim was to study the role of interhemispheric motor connections in genesis of different tremors. PATIENTS AND METHODS: We recorded the tremor of nine Parkinson patients and seven patients suffering from essential tremor using accelerometry. After Fast Fourier-transformation of digitized tremor signal we measured the power changes at the peak frequency after flash triggered movement (FM) and self-paced movement (SPM). For control we used flash signal without movement. RESULTS: Peak frequency of parkinsonian and essential tremor was not different. The power decrease of parkinsonian tremor was significant during flash triggered and self-paced movement compared to the effect of flash (p(Flash-FM)=0.0008; p(Flash-SPM)=0.002), changes during the different movement protocols were not different (p(FM-SPM)=0.33). During self-paced movement parkinsonian tremor became significantly smaller than essential tremor (p<0.05). The effect of movement was not significant on the power of essential tremor (p=0.42), probably due to high standard deviation of individual data. CONCLUSIONS: Voluntary movement of the contralateral hand decreases parkinsonian tremor suggesting that its generator can be inhibited via the activation of the motor cortex. The diverse reaction of essential tremor may reflect various connections between its generator system and the motor areas, therefore it is not a separate disease entity.

Aged↗

PubMed2003

Localization of thalamic cells with tremor-frequency activity in Parkinson's disease and essential tremor.

It has been reported that parkinsonian and essential tremor can be controlled by deep brain stimulation or radiofrequency lesion within the cluster of cells with a tremor-frequency activity in the ventral thalamic nuclei. However, there have been very few reports about the exact localization of cells with tremor-frequency activity in the ventral thalamic nuclei. In the present study, we investigated the localization of cells with tremor-frequency activity in the ventral thalamic nuclei employing autopower spectrum and coherence analysis. Activity of a total of 130 cells, 63 in patients with parkinsonian tremor and 67 in patients with essential tremor, were recorded from the area anterior to the nucleus ventralis caudalis. Among these cells, 31 cells showed a coherence of greater than 0.4 to the electromyographic activity of both agonist and antagonist muscles. The proportion of cells exhibiting tremor-frequency activity were 26.8% in the nucleus ventralis intermedius (Vim) and 25.0% in the nuclei ventralis oralis posterior et anterior (Vop + Voa). There were no significant differences in proportion by nuclear location or disease. The present study demonstrated that cells with tremor-frequency activity are widely distributed over the area extending from the Vim to the Vop + Voa. This indicates that the best location for placing electrodes for deep brain stimulation or a radiofrequency lesion cannot be defined by identification of cells with tremor-frequency activity alone.

Action Potentials↗

PubMed2001

Mild tremor in relatives of patients with essential tremor: what does this tell us about the penetrance of the disease?

BACKGROUND: Mild tremor may occur in relatives of patients with essential tremor (ET). However, this phenomenon has not been studied quantitatively or with a comparison group. Such a study may provide information on the penetrance of ET. OBJECTIVE: To obtain data on the magnitude of tremor in case and control relatives who did not meet diagnostic criteria for ET. METHODS: Cases with ET and control subjects from the Washington Heights-Inwood community in northern Manhattan, NY, were enrolled in a family study. Their first- and second-degree relatives underwent a videotaped tremor examination. Two neurologists rated the severity of tremor, assigning a total tremor score (0-36 [maximum]). Data were analyzed on 201 case relatives and 212 control relatives who did not meet diagnostic criteria for ET. RESULTS: The mean total tremor score of first-degree case relatives was higher than that of first-degree control relatives (4.9 vs 3.9; P<.003). Total tremor scores for second-degree relatives did not differ (4.1 vs 4.2; P =.68). A larger percentage (55.2% vs 36.6%; P =.01) of first-degree case relatives had total tremor scores of 4 or more. Among first-degree relatives who were older than 60 years, 13 case relatives (59.1%) and 18 control relatives (45.0%) had total tremor scores of 4 or more. CONCLUSIONS: A considerable number of seemingly normal case relatives may have a genetic predisposition for tremor. Even among older case relatives (> or =60 years of age), there was an increased prevalence of higher tremor scores, suggesting that in that age group, subclinical ET may be present and penetrance still may not be complete.

Adult↗

PubMed2001

Arm tremor in cervical dystonia differs from essential tremor and can be classified by onset age and spread of symptoms.

The pathophysiology of arm tremor in patients with cervical dystonia (CD) and its relationship to other types of tremor is unclear. In the present study, we have compared the tremor in these patients with that seen in patients with essential tremor (ET) using two neurophysiological techniques: the triphasic EMG pattern accompanying ballistic wrist flexion movements; and reciprocal inhibition between forearm muscles. During ballistic wrist flexion movements, the latency of the second agonist EMG burst was later in ET than CD patients. This suggests that the mechanism of the arm tremor in CD may differ from that in ET. There was no group difference between reciprocal inhibition in patients with ET or CD. However, there was much more variability in the data from patients with CD. Because of this, we subdivided the CD patients into two groups, group A with normal levels of presynaptic inhibition and group B with reduced or absent presynaptic inhibition. A posteriori, it turned out that the patients in these two subgroups had similar clinical symptoms, but different clinical histories. The arm tremor of patients in group A started simultaneously with torticollis (mean onset age of arm tremor 40 years +/- 20.7 SD, interval between onset of arm tremor and torticollis 0 +/- 2.9 years) whereas it began much earlier (mean onset age 14 years +/- 6 SD) and preceded onset of torticollis by a longer interval (21.6 +/- 17.5 years) in patients of group B. Patients in group A also had less co-contraction in their ballistic wrist movements between the first agonist and the antagonist burst than those patients in group B. We conclude that arm tremor in patients with CD may have a mechanism different from that seen in patients with ET. Moreover, the data imply that there are two subgroups of CD patients with arm tremor, one with a late and simultaneous onset of arm tremor and torticollis (group A), and another with an early onset of arm tremor and later development of torticollis (group B). These groups do not correspond to the currently proposed clinical subdivision of 'dystonic tremor' and 'tremor associated with dystonia'.

Adult↗

PubMed2001

Characteristics of social phobia among persons with essential tremor.

BACKGROUND: Social phobia symptoms have been reported to be common among patients with essential tremor, but characteristics of this comorbidity have not been systematically described. METHOD: Cases with essential tremor (N = 94) and controls without essential tremor (N = 85), ascertained from movement disorder clinic and community samples, were evaluated for social phobia symptoms (using the social phobia module of the Structured Clinical Interview for DSM-IV Axis I Disorders and the Liebowitz Social Anxiety Scale), characteristics of tremor, and associated disability (via videotaped examination, performance test, and disability questionnaire). RESULTS: Lifetime combined prevalence of primary social phobia and clinically significant social phobia symptoms occurring secondary to essential tremor was 32.7% (16/49) among essential tremor patients in the clinic sample. Essential tremor cases with secondary social phobia symptoms reported a markedly later age at onset of clinically significant social phobia symptoms than essential tremor cases with primary social phobia (51.0 vs. 8.8 years). Cases with secondary social phobia also reported greater fear and avoidance of eating, drinking, and writing in public than essential tremor cases with primary social phobia and control subjects with social phobia. Essential tremor cases with secondary social phobia symptoms also demonstrated more severe tremor and tremor-related disability than essential tremor cases with primary social phobia and essential tremor cases without social phobia. Among all essential tremor cases, severity of social phobia symptoms and tremor independently contributed to disability. CONCLUSION: Social phobia appears to occur in a substantial minority of essential tremor patients, and severity of social phobia symptoms is associated with disability, independent of tremor severity. Persons with social phobia symptoms secondary to essential tremor evidence clinical characteristics that differ from those of persons with primary social phobia. Further research is needed to determine the efficacy of treatment of social phobia in essential tremor patients with significant social phobia symptoms.

Age of Onset↗

PubMed1993

Significance of parkinsonian manifestations in essential tremor.

Parkinsonian features, notably resting tremor may be seen in some essential tremor patients but the significance of those is unknown. The reported risk of parkinsonism in essential tremor patients varies from being unchanged to 35 times higher than expected. We studied 9 patients with essential tremor who had autopsies. In 6 of the 9 (66%) resting tremor was noted and in 3 (33%) cases fully developed parkinsonism was noted. The parkinsonism was consequent to neuroleptic usage in 2 and to basal ganglia status lacunaris and cribrosus in one case but no consistent abnormalities were noted in 3 essential tremor only and 3 essential tremor plus resting tremor cases. We conclude that resting tremor is an age-related natural evolution in some essential tremor patients. We recommend that the additional diagnosis of parkinsonism in the essential tremor be made only when resting tremor, bradykinesia and rigidity are all evident. The risk of ideopathic Parkinson's disease in essential tremor cases is similar to the general population.

Aged↗

PubMed2003

Essential tremor: differential diagnosis and current therapy.

Essential tremor is a common movement disorder that affects between 5 and 10 million persons in the United States. It is characterized primarily by an action and postural tremor most often affecting the arms, but it can also affect other body parts. Essential tremor is a progressive neurologic disorder and can cause substantial disability in some patients. Although there is no cure for essential tremor, pharmacologic and surgical treatments can provide some benefit. Primidone and propranolol are first-line treatments. Other medications with potential efficacy include benzodiazepines, gabapentin, topiramate, and botulinum toxin. Patients with medication-resistant tremor may benefit from thalamotomy or deep brain stimulation of the thalamus. The use of medical and surgical therapies can provide benefit in up to 80% of patients with essential tremor.

Acetates↗

PubMedDate not supplied

Essential tremor and related disorders.

Essential tremor is a common neurological disorder. This article reviews the phenomenology of essential tremor and related disorders (excluding parkinsonian and dystonic tremors), summarising current theories on their pathogenesis. The various treatment options are also discussed.

Electromyography↗

PubMed1987

Essential tremor variants: effect of treatment.

Essential tremor may not represent a single condition. Subclassifications include kinetic predominant tremor; combined resting-postural tremor; primary writing tremor; isolated voice, chin, or tongue tremor; and orthostatic truncal tremor. We report patients with these disorders. An association of these conditions with essential tremor is suggested by a high occurrence of a family history of essential tremor, frequent presence of a mild postural tremor, and tremor reduction with alcohol ingestion. Pharmacologic responsiveness is different for these disorders. Propranolol and primidone often have beneficial effects but clonazepam was the only drug effective in some cases of kinetic predominant tremor and in orthostatic truncal tremor. Combined resting-postural tremor and voice tremor were often unresponsive to treatment.

Adult↗

PubMed1985

Handedness and essential tremor.

In patients with essential tremor, a direct relationship was found between hand dominance and severity of hand tremor. A higher incidence of left-handedness was found in patients with essential tremor than in controls.

Adolescent↗

PubMed1990

Limb positioning and magnitude of essential tremor and other pathological tremors.

We examined the influence of maintaining different postural configurations of the upper extremity on the magnitude of tremor in patients with essential tremor and with postural tremor from a variety of other neurological disorders. Patients maintained postures requiring different angles of forward flexion in the sagittal plane, of horizontal flexion, and of elbow extension. The tremor of patients diagnosed with essential tremor was either unaffected or affected only little by changes in limb position. In contrast, patients with pathological tremors, of the cerebellar postural, parkinsonian, and other types, exhibited positional dependence of their tremor. When there was positional dependence of tremor, it was always largest when the hands were near the nose or chin. These observations suggest a practical method for assistance with the clinical discrimination of essential tremor from other postural tremors.

Adult↗

PubMed1997

Prevalence of asymptomatic tremor in relatives of patients with essential tremor.

BACKGROUND: The extent to which essential tremor (ET) clusters within families (ie, the familial aggregation of ET) is not precisely known. In part, this is because studies assign disease status in relatives of patients with ET based solely on interviews without conducting physical examinations. This may lead to underascertainment of affected relatives with mild asymptomatic ET. OBJECTIVE: To determine the prevalence of asymptomatic ET among relatives of patients with ET. METHODS: Interview and examination of 25 patients with ET and 58 of their relatives. The interview included 12 questions that screened the patients for ET. Two neurologists who specialize in movement disorders reviewed the videotaped examinations. Based on standardized criteria, diagnoses included ET (definite, probable, or possible) on normal. RESULTS: Of the 8 relatives who received diagnoses of ET, 5 (62.5%) had asymptomatic ET. Hence, 5 (8.6%) of the 58 relatives (95% confidence interval 1.4%-15.8%) had asymptomatic ET. In those with asymptomatic ET, there was a preponderance of young individuals with mild tremor in the nondominant hand. CONCLUSIONS: The prevalence of asymptomatic ET in relatives of patients with ET was similar to that of symptomatic ET. Family studies that do not perform both an interview and a physical examination will underascertain the number of affected relatives. Therefore, future family studies should evaluate relatives of patients with ET with an interview supplemented by a physical examination.

Aged↗

PubMed1999

Acute and chronic effects of clozapine in essential tremor.

Patients with essential tremor (ET) may not respond to commonly used drugs. Clozapine, an atypical neuroleptic drug, has been reported to improve postural Parkinson's disease tremor clinically resembling ET. The effects of a single dose of 12.5 mg clozapine and placebo were evaluated in a randomized, double-blind, crossover study in 15 drug-resistant patients with ET. Patient responders with more than 50% improvement after a single dose of clozapine subsequently received the drug (39+/-9 mg up to 50 mg) unblinded for a period of 15.8+/-7.7 months. Tremor was effectively reduced by a single dose of clozapine in 13 of 15 patients (p <0.01). Sedation was the only side effect reported during the clozapine test; however, the time course of sedation and of the antitremor effect were not coincident. A significant reduction of tremor was reported with chronic clozapine treatment (p <0.01) with no tolerance to drug antitremor effect, whereas sedation markedly decreased after 6-7 weeks of therapy. No clozapine-induced hematologic side effects were observed in our cohort of patients during long-term treatment. Our results suggest that in selected drug-resistant ET cases, clozapine should be considered before resorting to neurosurgical options.

Antipsychotic Agents↗

PubMed1997

Agreement among movement disorder specialists on the clinical diagnosis of essential tremor.

Even though essential tremor (ET) is the most prevalent movement disorder, there has been little agreement in the neurologic literature regarding diagnostic criteria for ET. The authors attempted to determine the extent and source of agreement and disagreement among neurologists regarding diagnostic criteria for clinically definite ET. The authors designed and mailed a semistructured questionnaire to 160 neurologists who specialize in movement disorders in 24 countries. The questionnaire included three sections: a list of inclusion criteria, a list of exclusion criteria, and a list of potential clinical scenarios (for example, isolated site-specific tremor and primary orthostatic tremor). The questionnaire was completed by 98 (61%) of 160 targeted neurologists. There was greater consensus regarding features considered unnecessary inclusion criteria for clinically definite ET (extent of disability, disease duration, and positive family history) than for those considered necessary inclusion criteria (postural versus action tremor). With regard to exclusion criteria, there was some consensus in terms of the presence of Parkinson's disease, dystonia, history of hyperthyroidism or concurrent use of tremor-inducing medications, and cerebellar signs. The majority of neurologists would diagnose ET in the setting of isolated head or voice tremor. There are areas of both consensus and divergence among neurologists with regard to diagnostic criteria for ET. The choice of diagnostic criteria may vary depending on the intended use of the criteria (that is, clinical versus genetic studies). Hopefully, this study will foster further discussion to achieve a more general consensus.

Humans↗

PubMed2002

Essential tremor and cerebellar dysfunction: abnormal ballistic movements.

BACKGROUND: Clinical characteristics reminiscent of cerebellar tremor occur in patients with advanced essential tremor. Ballistic movements are known to be abnormal in cerebellar disease. The hypothesis was proposed that ballistic movements are abnormal in essential tremor, reflecting cerebellar dysfunction. OBJECTIVE: To elucidate the role of the cerebellum in the pathophysiology of essential tremor. METHODS: Kinematic parameters and the triphasic electromyographic (EMG) components of ballistic flexion elbow movements were analysed in patients assigned to the following groups: healthy controls (n = 14), pure essential postural tremor (ET(PT); n = 17), and essential tremor with an additional intention tremor component (ET(IT); n = 15). RESULTS: The main findings were a delayed second agonist burst (AG(2)) and a relatively shortened deceleration phase compared with acceleration in both the essential tremor groups. These abnormalities were most pronounced in the ET(IT) group, which had additional prolongation of the first agonist burst (AG(1)) and a delayed antagonist burst (ANT). CONCLUSIONS: Abnormalities of the triphasic pattern and kinematic parameters are consistent with a disturbed cerebellar timing function in essential tremor. These abnormalities were most pronounced in the ET(IT) group. The cerebellar dysfunction in essential tremor could indicate a basic pathophysiological mechanism underlying this disorder. ET(PT) and ET(IT) may represent two expressions within a continuous spectrum of cerebellar dysfunction in relation to the timing of muscle activation during voluntary movements.

Adult↗

PubMedDate not supplied

[Dysfunction of the upper respiratory airways in patients with essential tremor].

OBJECTIVES: To investigate pulmonary function abnormalities in essential tremor. METHODS: We obtained maximal inspiratory and expiratory flow-volume curves in 41 unselected patients with essential tremor (14 males, 27 females, age 61.7 +/- 2.14 years). Severity of essential tremor was evaluated using the Fahn, Tolosa and Marin clinical scale. RESULTS: Sixteen patients (39.0%) had flow oscillations on the flow-volume curves (8 only during inspiration, 7 during inspiration and expiration, and 1 with flow oscillations during inspiration and obstructive pattern). The duration and severity of the essential tremor did not influence the pattern of the curve, but abnormal curves were more frequent in patients with voice tremor. Although there were a number of significant correlations between essential tremor scales and spirographic parameters, they were of very low range. Four patients (9.8%) fulfilled criteria for physiological upper airway obstruction: 2 had smooth flow-volume loop contour and 2 had flow oscillations in inspiration and expiration. CONCLUSION: Abnormalities in flow-volume loop contour are a usual finding in essential tremor. This probably reflects involvement of the upper airway musculature, that in some patients can produce clinical upper airway obstruction.

Female↗

PubMed1986

Physiologic and essential tremor.

We studied physiologic and essential hand tremor using inertial loading; hand acceleration and forearm EMG data were analyzed by auto- and cross-spectral analysis. Early essential tremor was qualitatively similar to the 8- to 12-Hz component of physiologic tremor, suggesting that this tremor component is a forme fruste of essential tremor. Advanced essential tremor had a frequency of 4 to 8 Hz. Patients with tremor frequencies in both ranges were observed in each of 10 families. In antagonistic forearm muscles, both synchronous and alternating tremor bursts were observed in 11 of 44 patients. Essential tremor should not be classified solely on the basis of frequency or EMG pattern.

Adolescent↗

PubMed1987

A single family with writer's cramp, essential tremor, and primary writing tremor.

We studied seven members of a family who had different types of movement disorders: Two had typical essential tremor, two (twins) had typical writer's cramp, one had both essential tremor and writer's cramp, one had primary writing tremor, and one (deceased) had uncharacterized tremor. This appears to be the first report of writer's cramp in twins and in so many family members. This family links together primary writing tremor, essential tremor, and writer's cramp and may help resolve the apparent controversy about the relationship of primary writing tremor to essential tremor and writer's cramp.

Adult↗