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Validation of digital spiral analysis as outcome parameter for clinical trials in essential tremor.

ABSTRACT: Essential tremor, one of the most prevalent movement disorders, is characterized by kinetic and postural tremor affecting activities of daily living. Spiral drawing is commonly used to visually rate tremor intensity, as part of the routine clinical assessment of tremor and as a tool in clinical trials. We present a strategy to quantify tremor severity from spirals drawn on a digitizing tablet. We validate our method against a well-established visual spiral rating method and compare both methods on their capacity to capture a therapeutic effect, as defined by the change in clinical essential tremor rating scale after an ethanol challenge. Fifty-four Archimedes spirals were drawn using a digitizing tablet by nine ethanol-responsive patients with essential tremor before and at five consecutive time points after the administration of ethanol in a standardized treatment intervention. Quantitative spiral tremor severity was estimated from the velocity tremor peak amplitude after numerical derivation and Fourier transformation of pen-tip positions. In randomly ordered sets, spirals were scored by seven trained raters, using Bain and Findley's 0 to 10 rating scale. Computerized scores correlated with visual ratings (P < 0.0001). The correlation was significant at each time point before and after ethanol (P < 0.005). Quantitative ratings provided better sensitivity than visual rating to capture the effects of an ethanol challenge (P < 0.05). Using a standardized treatment approach, we were able to demonstrate that spirography time-series analysis is a valid, reliable method to document tremor intensity and a more sensitive measure for small effects than currently available visual spiral rating methods.

SUBMITTER: Haubenberger D

PROVIDER: S-EPMC4117681 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

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Validation of digital spiral analysis as outcome parameter for clinical trials in essential tremor.

Haubenberger Dietrich D Kalowitz Daniel D Nahab Fatta B FB Toro Camilo C Ippolito Dominic D Luckenbaugh David A DA Wittevrongel Loretta L Hallett Mark M

Movement disorders : official journal of the Movement Disorder Society 20110628 11

Essential tremor, one of the most prevalent movement disorders, is characterized by kinetic and postural tremor affecting activities of daily living. Spiral drawing is commonly used to visually rate tremor intensity, as part of the routine clinical assessment of tremor and as a tool in clinical trials. We present a strategy to quantify tremor severity from spirals drawn on a digitizing tablet. We validate our method against a well-established visual spiral rating method and compare both methods ...[more]

PMID: 21714004

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Project description:BackgroundFragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disease that affects carriers of a 55-200 CGG repeat expansion in the fragile X messenger ribonucleoprotein 1 (FMR1) gene, may be given an incorrect initial diagnosis of Parkinson's disease (PD) or essential tremor (ET) due to overlapping motor symptoms. It is critical to characterize distinct phenotypes in FXTAS compared to PD and ET to improve diagnostic accuracy. Fast as possible (FP) speed and dual-task (DT) paradigms have the potential to distinguish differences in gait performance between the three movement disorders. Therefore, we sought to compare FXTAS, PD, and ET patients using quantitative measures of functional mobility and gait under self-selected (SS) speed, FP, and DT conditions.MethodsParticipants with FXTAS (n = 22), PD (n = 23), ET (n = 20), and controls (n = 20) underwent gait testing with an inertial sensor system (APDM™). An instrumented Timed Up and Go test (i-TUG) was used to measure movement transitions, and a 2-min walk test (2MWT) was used to measure gait and turn variables under SS, FP, and DT conditions, and dual-task costs (DTC) were calculated. ANOVA and multinomial logistic regression analyses were performed.ResultsPD participants had reduced stride lengths compared to FXTAS and ET participants under SS and DT conditions, longer turn duration than ET participants during the FP task, and less arm symmetry than ET participants in SS gait. They also had greater DTC for stride length and velocity compared to FXTAS participants. On the i-TUG, PD participants had reduced sit-to-stand peak velocity compared to FXTAS and ET participants. Stride length and arm symmetry index during the DT 2MWT was able to distinguish FXTAS and ET from PD, such that participants with shorter stride lengths were more likely to have a diagnosis of PD and those with greater arm asymmetry were more likely to be diagnosed with PD. No gait or i-TUG parameters distinguished FXTAS from ET participants in the regression model.ConclusionThis is the first quantitative study demonstrating distinct gait and functional mobility profiles in FXTAS, PD, and ET which may assist in more accurate and timely diagnosis.

Project description:Essential tremor (ET) is among the most common neurological diseases and it often runs in families. How knowledgeable ET patients and their families are about their disease has been the subject of surprisingly little scholarship.To fill this gap in knowledge, we administered a comprehensive 32-item survey (i.e., questions about etiology, pathophysiology, symptoms and signs, natural history, and treatments) to 427 participants, including 76 ET probands, 74 affected relatives (AFRs), 238 unaffected relatives, and 39 spouses of unaffected relatives, all of whom were participating in two ET family studies. We hypothesized that there would be gaps in knowledge about ET and furthermore, that probands and AFRs would be the most knowledgeable, followed by unaffected relatives and then spouses of unaffected relatives, who would be the least knowledgeable.Overall, ET patients lacked knowledge about their disease. Nearly one-third of probands answered "yes" or "do not know" to the question, "is ET the same or different from the type of tremor that many normal people can get when they become old and frail?" A similar proportion did not know whether children could get ET or they responded "no." Nearly one-fourth of affecteds (i.e., probands and AFRs) did not know whether or to what degree (e.g., very well, moderately well, not well) the symptoms of ET could be medically controlled, and 38.0% either reported that there was no brain surgery for ET or reported that they did not know. Nearly 17% of affecteds did not endorse genes as a cause for ET, which was surprising given the fact that this was a family study of ET. Probands and AFRs were the most knowledgeable, followed by unaffected relatives. Spouses of unaffected relatives were the least knowledgeable.We targeted a large group of ET patients and their families, as this group is perhaps most likely to be informed about the disease. ET patients and their AFRs were more knowledgeable about the features of ET than their family members without ET. Overall, however, knowledge of ET was very limited and this lack of knowledge encompassed all aspects of the disease including its underlying causes, the nature of the symptoms and signs, its natural history and its treatment. Further ET awareness education and programs targeting both families of ET patients and the public would help alleviate this gap in knowledge.

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Validation of digital spiral analysis as outcome parameter for clinical trials in essential tremor.

Publications

Validation of digital spiral analysis as outcome parameter for clinical trials in essential tremor.

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