A teaching videotape for the assessment of essential tremor.

UNLABELLED: Teaching videotapes, developed to aid in the evaluation of several movement disorders, have not been used in essential tremor research. As part of the Washington Heights-Inwood Genetic Study of Essential Tremor (WHIGET), we developed a reliable and valid tremor rating scale. Because this rating scale is currently being used by investigators at other centers, we developed a teaching videotape to aid in the consistent application of this scale. OBJECTIVE: To develop a teaching videotape for a revised version of the WHIGET Tremor Rating Scale and to assess the interrater agreement among raters who used this videotape to rate tremor. METHODS: The revised WHIGET Tremor Rating Scale was used to rate action tremor from 0 to 4 during six tests: arm extension, pouring, drinking, using a spoon, finger-to-nose, and drawing spirals. A 22-minute teaching videotape was developed that includes a 29-item educational section and a self-assessment section consisting of 20 examples of tremor ratings chosen by the two WHIGET study neurologists. Eight raters, including senior movement disorder specialists, movement disorder fellows, general neurologists, and a movement disorder nurse practitioner, independently viewed the videotape and rated tremor during the self-assessment section. Interobserver reliability was assessed with weighted kappa statistics (kappa(w)). RESULTS: Eight raters each rated 20 items (160 ratings total). Total kappa(w) was 0.97 (nearly perfect agreement). Interrater reliability was as follows: kappa(w) = 0.99 (movement disorder specialists), kappa(w) = 0.98 (movement disorder fellows), and kappa(w) = 0.97 (general neurologists); all kappa(w) were nearly perfect. CONCLUSIONS: This teaching videotape may be used to improve the uniform application of the revised WHIGET Tremor Rating Scale by raters with various levels of experience in movement disorders.

Senile tremor. What is the prevalence and severity of tremor in older adults?

UNLABELLED: BACKGROUND/SETTING: It is well recognized that mild tremor is common among older adults, but the prevalence and clinical characteristics of this tremor have not been studied in detail. OBJECTIVES: To examine a cohort of normal older adults to: (1) ascertain the prevalence of mild test-detectible tremor; (2) quantify the severity and functional impact of this tremor, and (3) determine whether age, gender and concomitant illness predict the severity of tremor. PARTICIPANTS: 76 normal older adults >55 years of age (mean age = 73.7 years). DESIGN: Healthy older adults were identified in a community-based case-control study of essential tremor in Washington Heights-Inwood, New York. All subjects underwent a medical interview and a videotaped neurological examination. The examination included six tests: arm extension, pouring water, drinking water, using a spoon, finger-to-nose movements, and drawing spirals with each arm. Two neurologists rated the severity of tremor using a 0 to +3 clinical rating scale and a total tremor score (TTS) was calculated (range = 0-36). Forward stepwise linear regression was used to determine the association between TTS and other variables. RESULTS: Virtually all (75 or 98.7%) showed signs of tremor (TTS > 0.5). The mean TTS = 6.3 (range = 0-14.5), corresponding to a tremor that was either mild or intermittent. Twenty-eight of 76 (36.8%) received tremor ratings of +2 (clearly oscillatory tremor of moderate amplitude and usually present) during at least one of the six tests; a tremor rating of +2 was 2.1 times more likely to occur in the nondominant than in the dominant hand. Those who were aged 57-74 years had a lower mean TTS (5.8) than those aged 75-93 (6.8), but this was not significant. Only 2 patients (2.6%) answered 'yes' to the question 'do you have uncontrollable shaking in your hands?' None was taking medication to treat tremor. Gender, ethnicity, concomitant illness (diabetes, arthritis, heart disease), and medications were not associated with a higher TTS. CONCLUSION: Mild but test-detectible tremor was present in almost all normal older adults, and in one-third this tremor attained a moderate amplitude during at least one activity. Characterization of this tremor would be of value to practitioners who care for older adults.

Validity and test-retest reliability of a disability questionnaire for essential tremor.

BACKGROUND: One important outcome in clinical trials is patients' own opinions about whether the medication alleviates their symptoms and improves their ability to function. A valid and reliable method with which to assess this subjective information is important. OBJECTIVE: To determine the validity and test-retest reliability of the Columbia University Disability Questionnaire for Essential Tremor (ET). METHODS: Patients with ET underwent a 2.5-hour evaluation, including a 36-item tremor disability questionnaire, to assess the functional impact of tremor, a 26-item videotaped tremor examination rated by a neurologist, a 15-item performance-based test, and quantitative computerized tremor analysis. We determined the validity and test-retest reliability of the tremor disability questionnaire. Correlations between variables were assessed using Pearson's correlation coefficients and test-retest reliability with the weighted kappa statistic. RESULTS: Ninety-five patients with ET participated. The score on tremor disability questionnaire correlated with the neurologist's clinical ratings (r = 0.57, p <0.001) and the total score on the performance-based test (r = 0.69, p < 0.001). Correlations with quantitative computerized tremor analysis results were less robust, but each remained significant, including mean amplitude of dominant arm tremor while arms were extended (r = 0.56, p <0.001), while drawing a spiral (r = 0.42, p = 0.01), and while pouring (r = 0.34, p = 0.04). The questionnaire was readministered to 32 subjects, and the test-retest reliability was substantial (weighted kappa = 0.67). CONCLUSIONS: This Tremor Disability Questionnaire demonstrated substantial reliability, and it correlated with multiple measures of tremor severity, including a neurologist's clinical ratings, a performance-based test of function, and quantitative computerized tremor analysis results. The questionnaire would be useful in clinical trials in which it could be used as a reliable and valid tool to assess disability in ET.

Validation of a portable instrument for assessing tremor severity in epidemiologic field studies.

BACKGROUND: An important part of epidemiologic and genetic studies of essential tremor (ET) is an assessment of tremor severity. Clinical rating scales are semiquantitative and computerized tremor analysis, available at tertiary medical centers, is not transportable into the field. As part of an epidemiologic study, we modified the Klove-Matthews Motor Steadiness Battery, collecting objective quantitative data on tremor severity in patients with ET and control subjects. OBJECTIVE: To describe the modified Klove-Matthews Motor Steadiness Battery, validate this test battery against several other measures of tremor severity, demonstrate test-retest reliability, and provide standard reference values for normal control subjects and patients with ET who undergo this test battery. METHODS: Patients with ET and control subjects, ascertained from both a clinic and a community, underwent a standardized evaluation including a demographic and medical questionnaire, tremor disability questionnaire, videotaped tremor examination, performance-based test, modified Klove-Matthews Motor Steadiness Battery (Groove-Type Steadiness Tester [GTST] and Nine-Hole Steadiness Tester [NHST]), and quantitative computerized tremor analysis. RESULTS: There were 19 patients with ET and 28 control subjects. NHST and GTST total scores were correlated significantly with the tremor disability questionnaire score (r = 0.63, p = 0.001 and r = 0.49, p = 0.016), total tremor score (tremor examination, r = 0.68, p<0.001 and r = 0.41, p = 0.005), performance-based test score (r = 0.81, p<0.001 and r = 0.65, p = 0.001), and quantitative computerized tremor analysis results (for example, spiral drawing, r = 0.62, p = 0.01 and r = 0.58, p = 0.019). Test-retest reliability was generally high (r = 0.79-0.94, p<0.001). CONCLUSION: The modified Klove-Matthews Motor Steadiness Battery provides a reliable and valid means to collect objective quantitative data on tremor severity. Rapidity of administration and ease of transport make it a potentially useful tool in epidemiologic and genetic field studies.

Columbia University Assessment of Disability in Essential Tremor (CADET): methodological issues in essential tremor research.

Essential tremor (ET) is one of the most prevalent neurological disorders, affecting between 0.4 and 3.9% of the population. As there have been few studies of the functional impact of ET, knowledge of this area is limited. One study relied on subjective reports of tremor severity while a second focused on issues relating to treatment. Knowledge about the functional impact of ET is important for the valid assessment of efficacy in therapeutic trials as well as the diagnosis of ET in genetic and epidemiological studies. In order to examine the issue of functional disability in ET in greater detail, we designed the Columbia University Assessment of Disability in Essential Tremor (CADET). The critical elements of the study design have not been consistently applied to ET research to date. We describe this novel study.

Validity of a performance-based test of function in essential tremor.

BACKGROUND: The central factor influencing therapeutic decisions in essential tremor (ET) is the functional impact of the tremor. Neither the neurological examination nor computerized tremor analysis measures function. Questionnaires may assess function, but data are highly subjective. Performance-based tests of functional impairment provide an alternative means with which to assess the functional impact of ET. OBJECTIVE: To determine the internal consistency and validity of a performance-based measure of functional impairment in ET. METHODS: Subjects with ET from a community in northern Manhattan, NY, and from a clinic and control subjects each underwent a 2 1/2-hour evaluation including 12 screening questions for ET, a 31-item Tremor Disability Questionnaire to assess the functional impact of tremor, a 26-item Videotaped Tremor Examination that was rated by a neurologist, a 15-item, 10-minute Performance-Based Test, and Quantitative Computerized Tremor Analysis. Internal consistency was assessed with Cronbach alpha. The correlation between the Performance-Based Test and these other measures of tremor was assessed by means of correlation coefficients (r). RESULTS: There were 50 ET cases and 51 normal control subjects. The Performance-Based Test was internally consistent (Cronbach alpha = .92). It also demonstrated validity among cases; the total score correlated with the total number of screening questions answered yes (r = 0.44; P = .001), the total score on the Tremor Disability Questionnaire (r=0.55; P<.001), the total score on the Videotaped Tremor Examination (r=0.71; P<.001), and multiple physiological measures recorded during Quantitative Computerized Tremor Analysis. CONCLUSIONS: A valid performance-based test was developed to objectively assess functional capacity in patients with ET. This test would be useful in therapeutic trials, where it would provide an objective means to quantify the functional impact of tremor.

A comparison of different bedside tests for essential tremor.

OBJECTIVE: To compare the performance of different bedside tests for essential tremor (ET). BACKGROUND: Numerous tests (for example, writing, arm extension) may be used to elicit tremor in patients with ET. In large epidemiological surveys in which many patients must be evaluated efficiently, knowledge about the relative performance of these tests would be useful. METHODS: 154 subjects (42 with ET and 112 control subjects) were part of a community-based family study of ET in northern Manhattan, New York. Subjects underwent a tremor interview and a videotaped tremor examination which included six different tests for ET. Each of the six tests was performed with both the dominant and the nondominant arms. Two neurologists reviewed the videotaped examination and rated the severity of tremor during each test. Tremor ratings were 0 (none), +1 (mild), +2 (moderate), and +3 (severe). RESULTS: Among ET cases, there was considerable variation in the performance of each bedside test. With some tests (nondominant arm extension), as few as 48.8% of the ratings were >+2 and 29.8% of the ratings were 0 (no tremor). With other tests (finger-to-nose maneuver using nondominant arm), as many as 88.1% of the ratings were >+2 and only 2.4% were 0. Among the control subjects, there was also considerable variation in the performance of each test. Using some tests (finger-to-nose maneuver using nondominant arm), as many as 26.3% of the ratings were >+2, 72.8% were >+1 tremor, and only 27.2% of the ratings were 0. CONCLUSIONS: The performance of the tests varied considerably. In settings in which only one or two tests must be selected to screen a population, tests that are most likely to be abnormal in an ET case (finger-to-nose maneuver) could be used. In settings in which it is also desirable to exclude normal subjects, tests such as sustained arm extension, pouring water, or drawing a spiral could be used. Data regarding the performance of bedside tests for diagnosing ET are central to the design of research strategies for the clinical evaluation of patients with ET.

Validity of family history data on essential tremor.

BACKGROUND: In family studies of essential tremor (ET), valid data on the presence of ET in relatives of probands with ET is important. The family history method uses information obtained by interviewing probands with ET to identify ET in their relatives. The validation of this method by direct examination of the relatives has not been performed. OBJECTIVE: To determine the validity of family history data on ET in families in which the proband has ET. METHODS: ET cases (probands) and their respective relatives were enrolled in a genetic study of ET in Washington Heights-Inwood, New York. Each underwent a tremor interview and videotaped examination. Two neurologists rated the severity of tremor and assigned diagnoses (ET versus normal). Probands were asked to identify their relatives who had ET. The validity of the probands' responses was tested against the neurologists' diagnoses. RESULTS: There were 206 subjects: 46 ET cases and 160 relatives. Twelve (7.5%) of 160 relatives were diagnosed with ET (four definite ET and eight probable ET). Probands with ET reported that two of these 12 had tremor (sensitivity of probands' report = 16.7%). Six of the 12 affected relatives (50.0%) reported their own tremor. The probands reported that one of 136 of their unaffected relatives had tremor (specificity of probands' report = 99.3%). CONCLUSIONS: For family studies of ET, information on reportedly unaffected relatives is of limited use given the low sensitivity of family history data. The neurologic examination remains the only valid means of ascertaining cases of ET among relatives.

Is essential tremor symmetric? Observational data from a community-based study of essential tremor.

BACKGROUND: Essential tremor (ET) has been variably portrayed in the literature both as a symmetric arm tremor and as an asymmetric arm tremor. Few quantitative clinical or neurophysiological data specifically address the issue of tremor asymmetry in ET. OBJECTIVES: To examine a community-dwelling cohort of subjects with ET to (1) estimate the prevalence of tremor asymmetry and (2) quantify the magnitude of tremor asymmetry. METHODS: Fifty-four subjects with ET, identified in a community-based study of ET in New York City, underwent a Tremor Interview and a videotaped Tremor Examination. The examination included 6 tasks: sustained arm extension, pouring water, drinking water, using a spoon, finger-to-nose movements, and drawing spirals with each arm. Two neurologists rated the severity of tremor using a 0 to 3 clinical rating scale and a total tremor score was calculated (range, 0-36). Fourteen (25%) of 54 subjects also underwent quantitative computerized tremor analysis. RESULTS: The prevalence of asymmetry depended on the definition of asymmetry; small to moderate differences between sides were common. The mean side-to-side difference in clinical ratings for each of the 6 tasks was 0.54 of 3 points, which represented a 1.32-fold difference between sides. Clinical rating scores were higher in the nondominant arm in 39 subjects (72%), higher in the dominant arm in 9 (17%), and equal in 6 (11%). The 2 left-handed subjects had higher clinical ratings on the right. During quantitative computerized tremor analysis, there was a 1.71-fold mean difference between tremor amplitudes in the dominant and nondominant sides, and in 12 subjects (86%), the maximum tremor amplitude was in the nondominant arm. CONCLUSIONS: Small to moderate differences between sides were common in ET. In most community-dwelling subjects, tremor amplitude was greatest in the nondominant arm. In contrast, clinic-based studies have reported greater tremor in the dominant arm; those with ET who seek medical attention are more likely to exhibit severe tremor in their dominant arms. This study documents that mild asymmetry is a fundamental property of ET and that tremor is more severe in the nondominant arm.

Clinical characteristics of essential tremor: data from a community-based study.

BACKGROUND: 99.5% of individuals with essential tremor (ET) who live in the community have mild tremor and do not attend clinics. Clinic-based studies of ET have not allowed investigators to characterize the full clinical spectrum of this disorder. In community-based studies of ET, the primary focus has been the prevalence rather than the clinical characteristics of ET. OBJECTIVE: To describe the clinical characteristics of ET as seen in a community-based study. METHODS: 73 subjects with ET, identified in a community-based study of ET in Washington Heights-Inwood, New York, underwent a standardized 84-item physician-administered tremor interview and a 26-item videotaped tremor examination which included 12 bedside tests for ET. Two neurologists who specialized in movement disorders and who demonstrated excellent interrater agreement rated the severity of tremor using a 0 to +3 clinical rating scale and assigned a total tremor score (range, 0-36) and a diagnosis of ET. RESULTS: Diagnoses in the 73 cases were: definite ET (18, 24.7%), probable ET (32, 43.8%), and possible ET (23, 31.5%). The mean total tremor score was 17.8 of 36. Thirty-six of 73 (49.3%) were asymptomatic, answering "no" to the question "do you often have shaking or tremor that you can't control?" Sixty-seven of 73 (91.8%) had not been prescribed medication for tremor. On average, subjects received tremor ratings of > or =+2 on only 5.4 of the 12 bedside tests for ET. Kinetic tremor was rated as more severe than postural tremor in 72 (98.6%) of 73 cases. CONCLUSIONS: We present the clinical findings of a group of largely untreated, unselected cases of ET that would not otherwise have come to neurologic attention. The tremor was mild, often asymptomatic, and not uniformly present throughout the examination. It was rarely treated. The kinetic component of the tremor was more severe than the postural component. These clinical data further our understanding of the clinical spectrum of ET.