Validity of a Performance-Based Test of Function in Essential Tremor

Louis, Elan D.; Wendt, Kristin J.; Albert, Steven M.; Pullman, Seth L.; Yu, Qiping; Andrews, Howard

doi:10.1001/archneur.56.7.841

Cited by 115 publications

(117 citation statements)

References 36 publications

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“…The total tremor score, ranging from 0 to 36, was the sum of these two (Louis et al 2002). The reliability of this videotape-based rating has been demonstrated by weighted kappa statistics of 0.62 -0.78, indicating substantial inter-rater agreement (Louis et al 1998) and the score correlates with other objective measures of tremor severity (Louis et al 1999). …”

Section: History and Examinationsmentioning

confidence: 85%

Kinetic tremor: Differences between smokers and non-smokers

Louis

2007

NeuroToxicology

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Tremor is among the acute effects of nicotine exposure. Published studies have focused on smokingrelated postural (static) hand tremor rather than kinetic tremor (tremor during hand use), and gender differences in smoking-related tremor have not been examined. In a group of adults who were sampled from a population (mean ± SD = 65.7 ± 11.5 years, range = 18 -92 years), the investigator assessed whether the severity of postural and kinetic tremors differed in smokers versus non-smokers, and whether this difference was influenced by gender. Twenty-seven (9.9%) of 273 subjects were current smokers. Greater tremor was observed in smokers than non-smokers during a variety of activities (drawing a spiral, using a spoon, finger-nose-finger maneuver, all p < 0.05) and smokers had a higher total tremor score than non-smokers (5.15 ± 3.06 vs. 3.41 ± 2.88, p < 0.01), even after adjusting for age, caffeine intake and other potential confounding factors. The difference between smokers and non-smokers in terms of hand tremor was more apparent in women than in men. In women, the number of cigarettes smoked on the day of testing was weakly correlated with the total tremor score (r = 0.17, p = 0.03). In summary, smokers had more kinetic hand tremor than nonsmokers. This difference between smokers and non-smokers was more apparent in women than in men. These results suggest that smoking habits should be considered carefully in order to avoid overor underestimating the effects of occupational and non-occupational exposures to other tremorproducing neurotoxins.

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Section: History and Examinationsmentioning

confidence: 85%

Kinetic tremor: Differences between smokers and non-smokers

Louis

2007

NeuroToxicology

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“…An in-person evaluation was performed on all participants, during which they completed demographic, medical history and family history questionnaires, and underwent a videotaped neurological examination, from which a total tremor score (range 0-36) was assigned. 10,[33][34][35][36][37] After review of the questionnaires and videotaped examinations, the diagnosis of ET was then reconfirmed by a senior neurologist specializing in movement disorders (EDL) using reliable and valid research criteria. 38 All ET diagnoses (possible, probable and definite) required, at a minimum, moderate or greater amplitude kinetic tremor on at least three tasks, and an absence of other etiologies (eg, dystonia, PD and drug-induced tremor).…”

Section: Study Participants and Clinical Diagnosismentioning

confidence: 99%

Identification of candidate genes for familial early-onset essential tremor

et al. 2015

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Essential tremor (ET) is one of the most common causes of tremor in humans. Despite its high heritability and prevalence, few susceptibility genes for ET have been identified. To identify ET genes, whole-exome sequencing was performed in 37 early-onset ET families with an autosomal-dominant inheritance pattern. We identified candidate genes for follow-up functional studies in five ET families. In two independent families, we identified variants predicted to affect function in the nitric oxide (NO) synthase 3 gene (NOS3) that cosegregated with disease. NOS3 is highly expressed in the central nervous system (including cerebellum), neurons and endothelial cells, and is one of three enzymes that converts L-arginine to the neurotransmitter NO. In one family, a heterozygous variant, c.46G4A (p. (Gly16Ser)), in NOS3, was identified in three affected ET cases and was absent in an unaffected family member; and in a second family, a heterozygous variant, c.164C4T (p.(Pro55Leu)), was identified in three affected ET cases (dizygotic twins and their mother). Both variants result in amino-acid substitutions of highly conserved aminoacid residues that are predicted to be deleterious and damaging by in silico analysis. In three independent families, variants predicted to affect function were also identified in other genes, including KCNS2 (KV9.2), HAPLN4 (BRAL2) and USP46. These genes are highly expressed in the cerebellum and Purkinje cells, and influence function of the gamma-amino butyric acid (GABA)-ergic system. This is in concordance with recent evidence that the pathophysiological process in ET involves cerebellar dysfunction and possibly cerebellar degeneration with a reduction in Purkinje cells, and a decrease in GABA-ergic tone.

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“…Tremor severity of the upper limbs was assessed according to the Fahn-Tolosa-Marin Tremor Rating Scale 20 and item "drinking from a cup" from the Washington Heights-Inwood Genetic Study of Essential Tremor Rating Scale. 21 The Tremor Rating Scale items included resting, postural, and action/intention tremor using the finger-tonose test (for each of these items, scores ranged from 0 5 no tremor to 4 5 severe tremor, with amplitude .4 cm); handwriting (0 5 normal; 4 5 severely abnormal, unable to keep pen on paper without holding the hand down); drawing (Archimedes spirals A large); and pouring water from one cup to another (0 5 normal, 4 5 unable to pour water without spilling most of it) and drinking from a cup (0 5 normal, 4 5 unable to hold the cup). The global tremor score was calculated as the sum of the above-mentioned items (total score 5 28 if writing was considered, 24 if not).…”

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confidence: 99%

“…We found that the tremor score improvement was correlated with the ADL improvement (r 5 0.68; p , 0.0001). To determine the functional outcome of GKT, we divided the cohort into 2 groups according to ADL improvement: improved patients (IPs) ($50%) and nonimproved patients (NIPs) (,50% [14][15][16][17][18][19][20][21][22] for NIPs and IPs, respectively). Neither the tremor etiology (PD or ET) nor the tremor score severity influenced the outcome.…”

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confidence: 99%

A prospective single-blind study of Gamma Knife thalamotomy for tremor

et al. 2015

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Objective: To evaluate the safety and efficacy of unilateral Gamma Knife thalamotomy (GKT) for treatment of severe tremor with a prospective blinded assessment.Methods: Fifty patients (mean age: 74.5 years; 32 men) with severe refractory tremor (36 essential, 14 parkinsonian) were treated with unilateral GKT. Targeting of the ventral intermediate nucleus (Vim) was achieved with Leksell Gamma Knife with a single shot through a 4-mm collimator helmet. The prescription dose was 130 Gy. Neurologic and neuropsychological assessments including a single-blinded video assessment of the tremor severity performed by a movement disorders neurologist from another center were performed before and 12 months after treatment. MRI follow-up occurred at 3, 6, and 12 months. Results:The upper limb tremor score improved by 54.2% on the blinded assessment (p , 0.0001). All tremor components (rest, postural, and intention) were improved. Activities of daily living were improved by 72.2%. Cognitive functions remained unchanged. Following GKT, the median delay of improvement was 5.3 months (range 1-12 months). The only side effect was a transient hemiparesis associated with excessive edema around the thalamotomy in one patient. Conclusion:This blinded prospective assessment demonstrates that unilateral GKT is a safe and efficient procedure for severe medically refractory tremor. Side effects were rare and transient in this study. Classification of evidence:This study provides Class IV evidence that for patients with severe refractory tremor, GKT is well tolerated and effective in reducing tremor impairment. The pharmacologic treatment for severe tremor can be disappointing.

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Validity of a Performance-Based Test of Function in Essential Tremor

Abstract: 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.

Cited by 115 publications

References 36 publications

Kinetic tremor: Differences between smokers and non-smokers

Kinetic tremor: Differences between smokers and non-smokers

Identification of candidate genes for familial early-onset essential tremor

A prospective single-blind study of Gamma Knife thalamotomy for tremor

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