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Mirror movements in patients with essential tremor

Authors

  • Elan D. Louis MD, MS,

    Corresponding author
    1. GH Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, New York, USA
    2. Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, New York, USA
    3. Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, New York, USA
    4. Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA
    • Unit 198, Neurological Institute, 710 West 168th Street, New York 10032, NY, USA
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  • Eileen Rios BS,

    1. GH Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, New York, USA
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  • Claire Henchcliffe MD, DPhil

    1. Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York, USA
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  • Potential conflict of interest: Nothing to report.

Abstract

Mirror movements (MM), which occur in age-related neurodegenerative diseases such as Parkinson's disease (PD), have never been studied in essential tremor (ET). The objective of this work is to study the prevalence and clinical correlates of MM in ET cases and controls. In a clinical-epidemiological study in New York, participants performed repetitive motor tasks; MM (hands and feet) were rated. MM occurred in 35/107 (32.7%) ET cases versus 23/97 (23.7%) controls (OR 1.56, P = 0.16). Total MM score was 2× higher in cases (3.9 ± 7.7 vs. 1.9 ± 3.9, P = 0.02). MM (hands) occurred in 16 (15.0%) cases versus 5 (5.2%) controls (OR 3.24, P = 0.03) and total hand MM score was three to four times higher in ET cases (1.4 ± 4.5 vs. 0.4 ± 2.0, P = 0.03). MMs were not correlated with age, tremor duration, or severity and were most severe in cases with rest tremor. Thus, it was concluded that MM occurred in 1/3 of ET cases. These results further expand the spectrum of nontremor, motor phenomenology seen in ET. Whether, as in PD, MMs in ET represent a failure of subcortical structures to support the cortical network involved with the initiation of unilateral motor activity, requires future neurophysiological investigation. © 2009 Movement Disorder Society

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