Characterization of subclinical tremor in Parkinson's disease

Authors

  • Anne Beuter PhD,

    Corresponding author
    1. Institut de Cognitique, EA 487, Université de Victor Segalen Bordeaux 2, Bordeaux, France
    • Institut de Cognitique, Université de Bordeaux 2 146 rue Léo Saignat, (EA 487) 33076 Bordeaux, France
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  • Emilie Barbo MD,

    1. Université du Québec à Montréal, Département de Kinanthropologie et Centre de Neuroscience de la Cognition, Montréal, Canada
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  • Robert Rigal PhD,

    1. Université du Québec à Montréal, Département de Kinanthropologie et Centre de Neuroscience de la Cognition, Montréal, Canada
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  • Pierre J. Blanchet MD, FRCP(C), PhD

    1. Department of Stomatology, Faculty of Dental Medicine, Université de Montréal and Research Centre, Université de Montréal Hospital Centre (CHUM), Montréal, Canada
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Abstract

The physiological or pathological nature of subclinical tremor amplitude in Parkinson's disease (PD) is not well established. We analyzed characteristics of resting and postural tremors of subclinical amplitude in 17 patients with idiopathic PD without visible resting tremor, having a postural tremor in their least-affected hand rated 0 (12 subjects) or 1 (5 subjects) on Item 21 of the Unified Parkinson's Disease Rating Scale, compared to 17 control subjects matched for age, sex, and handedness. Tremor was recorded at the tip of the index finger using a displacement laser transducer. Overall results show that subclinical resting tremor in PD is significantly different from physiological tremor in terms of amplitude fluctuation, frequency dispersion, harmonic index, and proportional power in 4 to 6 Hz. No significant differences were found for postural tremor. These differences appear to originate mainly from patients with the mixed form of the disease. This study also confirms the preservation of physiological tremor likely originating from a distinct central oscillator in PD. The use of this method in the early and detailed characterization of PD tremors when amplitude is still within normal limits is proposed. © 2005 Movement Disorder Society

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