Essential tremor in a Finnish population

A two-phase epidemiological study of essential tremor was carried out by investigating a rural population aged over 40 years in 2 municipalities in southwestern Finland. In the first phase, the subjects answered a questionnaire as to whether they had experienced tremor during the month preceding the inquiry. In the second phase, the persons who had tremor often or fairly often, were examined clinically. The total prevalence of essential tremor, calculated on the basis of clinically established cases, was 55.5‰ of the population aged over 40 years. The disease became more prevalent with advancing age and was, with the exception of the oldest age-group, more common in men than in women.     

A clinical study of non-parkinsonian tremor in Moroccan patients

Objective

To report the characteristics of the most frequent tremors in a population of Moroccan patients.

Background

Tremor is the most common movement disorder. It implies a wide variety of disorders with Parkinson's disease and essential tremor being the most frequent.

Methods

A retrospective study of 148 patients with tremor referred to our movement disorders outpatient clinic was performed. Clinical features and treatment regimens were analyzed. Patients with parkinsonian tremor were excluded.

Results

We included 62 patients with non-parkinsonian tremor. The etiologies were as follows: essential tremor (54.8%), dystonic tremor (19.4%), tremor associated with dystonia (14.5%), enhanced physiological tremor (3.2%), cerebellar tremor (3.2%), psychogenic tremor (3.2%) and Holmes’ tremor (1.6%). The characteristics of essential tremor patients were analyzed. Female patients accounted for 67.6% of patients. Mean age at the onset of tremor was 52.2 ± 16.4 years. Family history of tremor was reported in 17.6% of cases. Tremor affected the arms (94.1%), head (52.9%), voice (35.3%) and legs (8.8%). Tremor was bilateral in 87.5% but was asymmetrical in 50% of patients. Patients had postural tremor (76.5%), kinetic tremor (79.4%) and rest tremor (associated in 11.8%). Treatment relied on propranolol (88.3%), primidone (14.7%), gabapentin (14.7%), clonazepam (14.7%), alprazolam (11.8%), topiramate (5.9%) and, in one patient, radiosurgery.

Conclusions

Essential tremor was the predominant diagnosis, confirming its high prevalence. There was a predominance of female patients and a peak of age at onset in the fifth and sixth decades. Asymmetry of the disease was noted in half of patients.     

Essential tremor prevalence is low in Arabic villages in Israel

Objective To estimate the prevalence of essential tremor (ET) in Arabic villages of Wadi Ara. Background The prevalence ET which is higher than Parkinson’s disease in North America and Europe, differs according to study population and methodology. Since hospital record based epidemiology carries referral bias and might provide low estimates of ET prevalence, we carried a population based survey. Methods This door-to-door survey comprised the Arabic villages of Wadi Ara in Northern Israel. Consecutive residents who agreed to participate in the study and were older than 64 years at prevalence day, underwent neurological examination. Medical and family history, medication and response to medication were recorded. Results Of the 444 subjects that were approached, 428 agreed to participate in the study (refusal rate 3.6%). Four were excluded owing to severe systemic disease. The study population consisted of 424 subjects (54% men, mean age 74 ± 7 years). A clearly oscillatory action tremor of moderate amplitude was observed in 8 patients (age 75 ± 7 years). Six patients had another possible cause of tremor. The prevalence of ET was calculated as 1.89% (95% CI 1.76–2.0) when all tremor cases were accepted as possible ET and 0.47% (95 CI 0.43–0.52) when patients with other causes of tremor were excluded. Conclusions The prevalence of ET in Arabic villages of Wadi Ara is low. Received in revised form: 17 January 2006     

Prevalence of essential tremor in three elderly populations of central Spain.

Although essential tremor (ET) is considered the most prevalent adult movement disorder, the available information on its prevalence and distribution worldwide is not completely understood. We investigated the prevalence and distribution of ET in three elderly Spanish populations using a door-to-door, two-phase approach. A brief screening instrument was administered on May 1, 1994 to subjects over 64 years old taken from the census of one urban municipality of Greater Madrid (quarter of Margaritas, Getafe), one urban district of Madrid (Lista), and one rural site (Arévalo county, Avila) (N = 5278). Study subjects were limited to those who screened positively (N = 472). To increase reliability, each patient was examined by 3 experienced neurologists, and was classified as having ET only when all 3 neurologists agreed (183 of 472). The present study was part of a large-scale epidemiological survey of neurological diseases, and served as a baseline investigation in a 3-year incidence study. Accordingly, 41 ET patients were identified when evaluating subjects who had screened positively for dementia, stroke, or parkinsonism, despite the fact that they had screened negatively for tremor; furthermore, 32 additional ET prevalent cases were detected when evaluating subjects who had screened positively for tremor in the second cross-sectional study (May 1, 1997), although they had screened negatively for tremor in the first cross-sectional study. We identified 256 persons (152 women, 104 men) with ET; of these, 87 patients (34.0%) reported having an affected relative. Two hundred and four (79.7%) of the subjects with ET were detected through this screening and had not been diagnosed previously. The prevalence of ET was 4.8% (95% CI = 4.2-5.4) for the total population; 4.6% (95% CI = 3.7-5.4) in men and 5.0% (95% CI = 4.2-5.8) in women. Age-specific prevalence increased with advancing age for both men and women. Despite the variability in worldwide data, ET is a frequently encountered disorder in elderly people. Furthermore, as ET may be seen as a relatively benign condition, a large proportion of patients may never seek neurological attention.     

Tremor severity and age: A cross‐sectional,population‐based study of 2,524 young and midlife normal adults

Mild action tremor occurs in most normal people. Yet this tremor mainly has been studied within the context of advanced age rather than among the vast bulk of adults who are not elderly. Whether this tremor worsens during young and middle age is unknown. Using cross‐sectional data from a large population‐based study of young and midlife normal adults (age range, 18–60 years), we assessed whether increasing age is associated with more severe action tremor. Two thousand five hundred and twenty‐four adults in Araihazar, Bangladesh, drew an Archimedes spiral with each hand. Tremor in spirals was rated (0–3) by a blinded neurologist, and a spiral score (range, 0–6) was assigned. Spiral score was correlated with age (r = 0.06, P = .004). With each advancing decade, the spiral score increased (P = .002) so that the spiral score in participants in the highest age group (age 60) was approximately twice that of participants in the youngest age group (age 18–19); P = .003. In the regression model that adjusted for potential confounders (sex, cigarettes, medications, asthma inhalers, and tea and betel nut use), spiral score was associated with age (P = .0045). In this cross‐sectional, population‐based study of more than 2500 young and midlife normal adults, there was a clear association between age and tremor severity. Although the magnitude of the correlation coefficient was modest, tremor severity was higher with each passing decade. These data suggest that age‐dependent increase in tremor amplitude is not restricted to older people but occurs in all adult age groups. © 2011 Movement Disorder Society     

Bilaterally coherent tremor resembling enhanced physiological tremor: report of three cases.

The contribution of the central nervous system to tremor pathogenesis is unclear. Poor side-to-side coherence in physiological, essential, and parkinsonian tremors suggests distinct bilateral generators. By contrast, significant bilateral coherence demonstrated in orthostatic tremor and in enhanced physiological tremor (EPT) in patients with persistent mirror movements favours single or closely linked bilateral oscillators. We describe three patients (aged 21-37 years) who developed unusual bilateral postural and kinetic tremors at 6-13 Hz resembling EPT. The tremor involved all limbs, and in two cases the face or jaw, in the absence of other significant neurological features. Significant side-to-side coherence was demonstrated in each case using cross-correlation of electromyographic recordings from homologous muscle pairs. We postulate that these unusual tremors originate from a single brainstem source or from bilateral oscillators closely linked at or below this level.     

Jaw tremor: prevalence and clinical correlates in three essential tremor case samples.

The spectrum of involuntary movements seen in essential tremor (ET) is limited. Jaw tremor is one such movement. The prevalence and clinical correlates of jaw tremor have not been studied in detail. The objective of this study was to estimate the prevalence and examine the clinical correlates of jaw tremor in ET using ET cases from three distinct settings (population, tertiary-referral center, brain repository). All ET cases underwent a videotaped tremor examination in which tremors (including limb, head, voice, and jaw) were assessed. The prevalence [95% confidence interval (CI)] of jaw tremor was lowest in the population sample (7.5%; 3.9%-14.2%), intermediate in the tertiary-referral center (10.1%; 6.8%-14.7%), and highest in the brain repository (18.0%; 12.3%-25.5%; P = 0.03). Jaw tremor was associated with older age (P < 0.001), more severe action tremor of the arms (P < 0.001), and presence of head and voice tremor (P < 0.001). Jaw tremor was present in 4/14 (28.6%) ET cases with consistent rest tremor vs. 15/193 (7.8%) cases without rest tremor (odds ratio = 4.8; 95% CI = 1.3-7.0; P = 0.009). The prevalence of jaw tremor was 7.5% to 18.0% and was dependent on the mode of ascertainment, being least prevalent in a population-based sample. ET cases with jaw tremor had a more clinically severe and more topographically widespread disorder. The association in our study between jaw tremor and rest tremor, along with the published observation that jaw tremor can occur in Parkinson's disease (PD), raises the question whether jaw tremor in ET is a marker for subsequent conversion to PD.     

合并静止性震颤的原发性震颤患者临床特点分析

目的了解北京地区社区中老年人原发性震颤(essential tremor,ET)的临床特征及其与预后的关系。方法2000年在北京城区、近郊平原、远郊山区调查了2835名55岁以上中老年人,采用筛查和临床诊断两步法确诊患者。发现ET患者135例,对其中合并静止性震颤的患者进行分析,并于2004年对其进行随访。结果其中合并上肢静止性震颤患者17例,占12.6%,合并静止性震颤组震颤总分、头部震颤的比例、肢体震颤总分均明显高于对照组。两组年龄、性别组成、病史无显著性差异,姿势性震颤和动作性震颤的程度差异不明显。4年后随访到13例(13/17),其中3例死亡,实际调查的10例中有9例仍诊断为ET,另1例诊断为临床很可能ET。结论有相当部分社区ET患者可以合并静止性震颤,合并静止性震颤的患者提示病情较重。     

Triggering essential head tremor with sustained phonation: A clinical phenomenon with potential diagnostic value

Here we report a clinical phenomenon that we have observed repeatedly in clinical research settings; namely, a triggering and/or exacerbation of head tremor during or immediately following sustained phonation. To our knowledge, it has not been reported previously nor has it been the subject of study. Here we: 1) report the phenomenon, 2) provide several visual illustrations, 3) estimate its prevalence, and 4) analyze its clinical correlates. Head tremor was assessed qualitatively, and scores were assigned pre-, during, and post-sustained phonation using the Tremor Research Group Essential Tremor Rating Assessment Scale. Seventy (68.6%) of 102 essential tremor (ET) patients exhibited a qualitative increase in head tremor amplitude during and/or immediately after sustained phonation; in 5 (4.9%), head tremor would not have been detected without the voice activation maneuver (i.e., it was not visible at any other point in the videotape aside from the period during/immediately following sustained phonation). Women were more likely than men to exhibit this phenomenon (p = 0.05), whereas age, age at onset, duration of tremor, and total tremor score did not predict responsiveness of head tremor to sustained phonation. Sustained voice activation is a useful examination maneuver that may elicit or amplify head tremor in ET. Head tremor is not reported to occur in patients with enhanced physiological tremor. Thus, this maneuver, by triggering head tremor, may be a useful diagnostic supplement, particularly in research/clinical settings where arm tremor is mild and the diagnosis (mild ET vs. enhanced physiological tremor) would otherwise be ambiguous.     

Clinical characteristics of essential tremor in Taiwan: an exploratory‐comparative study

Background: There are few large‐scale clinical analyses of essential tremor (ET) in Asia. We studied the detailed clinical profile with emphasizing the age of onset, tremor location, specific tremor patterns, and rate of progression (ROP) to delineate the characteristics of Taiwanese ET patients and found the difference between the Taiwanese and the Caucasians ET patients. Methods: All ET patients fulfilled the Movement Disorders Society diagnosis criteria were investigated with a standardized assessment protocol, which including clinical evaluation, uniform severity scoring, self‐reported questionnaires, accelerometry, surface electromyography, and videotaped tremor examination. Results: Of 219 patients recruited from July 2008 to October 2009, 153 completed the study protocol. Their mean age was 58.9 years and 47% were women, and 33.3% had family history (FH). There was bimodal distribution in age of tremor onset in patients without but not in those with FH. Head tremor (HT) was present in 48 of 153 (31%) patients. Patients with HT showed slower tremor frequency and less ROP than those without HT. Sixty‐seven (44%) patients presented with intention tremor (IT). Male gender and voice tremor were predictive factors of IT occurrence. Conclusions: Comparing with the Caucasians, Taiwanese ET patients have different patterns of onset‐age distribution and lack of female predominance in ET with HT. However, patients with IT and without HT also progressed more rapid as found in the Caucasian.     

Tremor on smiling

Facial tremor occurring on smiling is a rare phenomenon and has been described (to the best of our knowledge) in the literature only once. We describe two patients who presented with a bilateral facial tremor that occurred only on smiling and other activation of therisorii muscles and had a high frequency of 9 Hz. One patient additionally suffered from young‐onset Parkinson's disease, whereas the other had no further neurological symptoms or signs apart from this tremor. Anti‐parkinsonian medication was unhelpful for the facial tremor in the patient with Parkinson's disease. Tremor on smiling may be a discrete entity or may be associated in some cases of Parkinson's disease. © 2009 Movement Disorder Society     

Subclinical tremor in normal controls with versus without a family history of essential tremor: data from the United States and Turkey

Background and purpose: Mild action tremor is very common in the population. One fundamental question is whether this tremor is related to the neurological disease essential tremor (ET), which occurs in a much smaller segment of the population? ET is often genetic, and variable phenotypic expression is well‐documented in the literature. We determined whether normal controls who report a family history of ET have greater action tremor than normal controls who do not report such a history. Methods: Controls, enrolled in two epidemiological studies (New York and Turkey), were examined in detail and action tremor was rated using a valid and reliable clinical rating scale, resulting in a total tremor score (range 0–36). Results: In New York, the total tremor score was higher in 44/406 (10.8%) controls who reported a family history of ET than in 362/406 controls with no such history (4.25 ± 2.51 vs. 3.78 ± 2.93, P = 0.02). Controls who reported a first‐degree relative with ET had the highest total tremor scores. In Turkey, the total tremor score was higher in 7/89 (7.9%) controls with a family history than in 82/89 controls with no family history (3.43 ± 4.54 vs. 1.13 ± 2.54, P = 0.048). All affected relatives in Turkey were first‐degree. Conclusions: These data suggest that some of the normal tremor exhibited by people in the population is likely to be subclinical, partially expressed ET and that the sphere of ET is wider than is apparent from a consideration of clinically diagnosed cases.     

How are we doing with the treatment of essential tremor (ET)?

Background: The pharmacological treatment of essential tremor (ET) is not optimal. There are only two first‐line medications and troublesome side effects are common. It is not uncommon for patients to simply stop taking medication. Yet, no published data substantiate or quantify this anecdotal impression. Objectives: To determine, amongst patients with ET who were prescribed medication for tremor, what proportion are still taking medication and what proportion have stopped? Methods: Five hundred and twenty‐eight patients with ET from three distinct study settings (clinical, brain donors, population) were interviewed. Results: A clear pattern that emerged across settings was that the proportion of patients with ET who had stopped medication was sizable and consistently similar (nearly one‐third): 31.4% (clinical), 24.3% (brain donors), 30.0% (population), 29.8% (overall). A similarly high proportion of cases with severe tremor had stopped their medication: 31.9% (clinical), 36.4% (brain donors). For the four most commonly used medications (propranolol, primidone, diazepam, topiramate), one‐half or more of the treated patients had stopped the medication; amongst the less commonly used medications, the proportion who stopped was even higher. Conclusions: Nearly one of every three patients with ET who had been prescribed medication for tremor had discontinued pharmacotherapy. Even more revealing was that a similar proportion of cases with severe tremor had stopped medication. These data make tangibly evident that there is a sizable population of patients with ET who are untreated and disabled, and underscore the inadequacy of current pharmacotherapeutic options for this common neurological disease.     

Tremor is attenuated during walking in essential tremor with resting tremor but not parkinsonian tremor

We used accelerometry and visual examination by a neurologist to measure the intensity and frequency of hand tremor under resting, postural, writing, and walking conditions among patients with essential tremor with resting tremor (n = 11) and Parkinson’s disease (n = 38). The intensity of essential tremor was markedly attenuated during walking relative to resting. The intensity and frequency of parkinsonian tremors were higher while walking than while resting. We suggest that assessment of the intensity and frequency of tremor during walking is clinically useful for differentiating between essential tremor with resting tremor and parkinsonian tremor, especially in the early stages, when the two conditions are often difficult to distinguish. Parkinsonian tremors are known to be enhanced during walking. Our clinical experience, as well as that of others, suggests that the intensity of essential tremor with resting tremor is markedly attenuated during walking.     

Regional and racial differences in the prevalence of physician-diagnosed essential tremor in the United States.

For reasons that are unclear, prevalence estimates of essential tremor (ET) differ considerably across the United States. Separate communities have never been sampled within the framework of the same study to substantiate these differences. We estimated the prevalence of physician-diagnosed ET in the elderly in four communities in the United States in whom the same screening questions were used, and examined whether this prevalence differed between Caucasians and African Americans. The Cardiovascular Health Study recruited a sample of Medicare beneficiaries >/=65 years of age from four communities in different regions of the United States. In 1998 to 1999, 3,494 participants (mean age, 80.0 years; range, 70-103 years) answered a 12-question screen for ET, including the question, "has a doctor diagnosed you as having familial tremor or benign essential tremor?" Fifty-four participants reported that a doctor had diagnosed them as having ET (1.5%; 95% confidence interval, [CI], 1.1-2.0%). Prevalence was similar across the four communities (1.1-2.0%). A larger proportion of Caucasians than African Americans reported a diagnosis of ET (1.7% vs. 0.4%; odds ratio = 4.9; 95% CI, 1.2-20.2; P = 0.028). In a logistic regression analysis, physician-diagnosed ET was associated with Caucasian ethnicity (P = 0.038) but not with age, gender, education, mental status or depression scores, income, smoking status, or alcohol consumption. When a standardized screening question was used, the proportion of participants with physician-diagnosed ET was similar across four communities, suggesting that the prevalence of this condition may be less variable than is often reported. Caucasians were five times more likely to have physician-diagnosed ET than were African Americans. This study does not provide an explanation for this difference, which deserves further study.     

Long-term EMG recordings differentiate between parkinsonian and essential tremor

The differential diagnosis of tremor is mainly based on clinical criteria.Nevertheless, these criteria are in some cases not sufficient to differentiate between different tremor forms. Long-term EMG has proven to be a valid and reliable method for the quantification of pathological tremors. The aim of the study was to develop a long-term EMG-based automated analysis procedure that separates parkinsonian tremor from essential tremor. Using longterm EMG tremor was recorded in 45 consecutive patients, 26 with Parkinson's disease (PD) and 19 with essential tremor (ET). Eight tremor parameters were generated automatically. By stepwise backward regression a subset of these criteria was extracted to achieve an automated classification of the tremor by a mathematical model. The obtained model was then tested on a new group of 13 patients in early stages of the disease. Significant differences between groups were found for tremor occurrence, tremor asymmetry, mean tremor frequency and standard deviation of phase of antagonistic muscles. Due to data overlap a classification of the two tremor forms was not possible based on a single tremor parameter. Using logistic regression, a linear formula based on the three parameters tremor occurrence, mean tremor frequency and standard deviation of phase was established and predicted the correct diagnosis in 93% of patients. The validation of the model on the new group of patients in early stages of the tremor disease yielded a correct diagnosis in 100% of cases. We conclude that long-term EMG recording allows a rater-independent classification of parkinsonian versus essential tremor.     

Tremor in neurodegenerative ataxias,Huntington disease and tic disorder

IntroductionTremor is the most prevalent movement disorder, defined as rhythmic oscillations of a body part, caused by alternating or synchronic contractions of agonistic or antagonistic muscles. The aim of the study was to assess prevalence and to characterize parameters of tremor accompanying degenerative ataxias, Huntington disease (HD) and tic disorders in comparison with a control group.Material and methodsForty-three patients with degenerative ataxias, 28 with HD and 26 with tic disorders together with 51 healthy controls were included in the study. For each participant, clinical and instrumental assessment (accelerometer, electromyography [EMG], graphic tablet) of hand tremor was performed. Frequency and severity of tremor were assessed in three positions: at rest (rest tremor), with hands extended (postural tremor), during the ‘finger-to-nose’ test and during Archimedes spiral drawing (kinetic tremor). Based on the mass load test, the type of tremor was determined as essential tremor type or enhanced physiological tremor type.ResultsThe incidence of tremor in the accelerometry in patients with degenerative ataxia (50%) significantly differs from controls (10%) (p = 0.001). The dominant tremor was postural, low-intense, with 7-Hz frequency, essential tremor (23%) or other tremor type (23%), while enhanced physiological tremor was the least frequent (2%). Tremor in patients with HD and tic disorders was found in 10% and 20% of patients, respectively, similarly to the control group. Tremor was mild, postural and of essential tremor type, less frequently of enhanced physiological tremor type. No correlation between severity of tremor and severity of disease was found.ConclusionsThe prevalence of tremor is considerably higher among patients with degenerative ataxias compared with HD, tic disorder and the control group. The most common type of tremor accompanying ataxias, HD and tic disorders is essential tremor type.     

Intention tremor of the head in patients with essential tremor.

Patients with essential tremor (ET) have kinetic arm tremor; this tremor can also have an intentional component. We are unaware of reports of intention tremor of the head in ET. Our aims were to describe, provide electrophysiological data and video documentation of, and estimate the prevalence of intention tremor of the head in our sample. Ten (9.0%; 95% confidence interval = 4.7%-14.3%) of 111 patients had intention tremor of the head; in 7 it involved the neck and in 3 the chin. These patients trended toward having more severe kinetic arm tremor and they had more severe intention tremor of the arms. These observations provide further support for the evolving view that the cerebellum may be involved in ET.     

Essential tremor: an overdiagnosed condition?

The diagnosis of essential tremor (ET) and its differentiation from other types of tremor is often difficult. In 1994 Bain et al. defined a classical phenotype by studying 20 patients with pure essential tremor and similarly affected family members in at least three generations. We assessed how many of the patients diagnosed by different neurologists at our institution as having ET conformed to this defined phenotype. We randomly selected 50 patients who were diagnosed with ET by any neurologist at the National Hospital for Neurology and Neurosurgery since the publication of the Bain et al. report, and determined the number of patients who had clinical features compatible with the phenotype that it had defined. Only 25 (50%) of these patients had ET so defined. Ten patients clearly had alternative diagnoses: four had clear additional dystonia, two neuropathic tremor, two had unilateral leg tremor, one drud-induced tremor, and one sudden onset after head trauma. The remaining 15 patients also had atypical features including myoclonus (one), onset in a body part other than the arms (six), sudden onset (two), rest tremor (seven), onset after the age of 65 years (four), a family member with an isolated head tremor (one), or reduced armswing (two). The diagnosis of ET is overused even among experienced neurologists, and other types of tremor should be considered in atypical patients before making this diagnosis. Received: 30 November 1999 / Received in revised form: 12 May 2000 / Accepted: 21 June 2000     

Tremor associated with focal and segmental dystonia

Background and purposeTremor occurs in 10–85% of patients with focal dystonia as so-called dystonic tremor or tremor associated with dystonia. The aim of this study was to assess the incidence and to characterize parameters of tremor accompanying focal and segmental dystonia.Material and methodsOne hundred and twenty-three patients with diagnosis of focal and segmental dystonia together with 51 healthy controls were included in the study. For each participant, clinical examination and objective assessment (accelerometer, electromyography, graphic tablet) of hand tremor was performed. Frequency and severity of tremor were assessed in three positions: at rest (rest tremor); with hands extended (postural tremor); during ‘finger-to-nose’ test and during Archimedes spiral drawing (kinetic tremor). Based on the mass load test, type of tremor was determined as essential tremor type or enhanced physiological type.ResultsThe incidence of tremor was significantly higher in dystonic patients as compared to controls (p = 0.0001). In clinical examination, tremor was found in 50% of dystonic patients, and in instrumental assessment in an additional 10–20%. The most frequent type of tremor was postural and kinetic tremor with 7 Hz frequency and featured essential tremor type. In the control group, tremor was detected in about 10% of subjects as 9-Hz postural tremor of enhanced physiological tremor type. No differences were found between patients with different types of dystonia with respect to the tremor incidence, type and parameters (frequency and severity). No correlations between tremor severity and dystonia severity were found either.