Patrick McGurrin1, Felipe Vial1,2, Thomas Osterholt1, Gina Norato3, Imran Khan4, Dietrich Haubenberger1, Debra Ehrlich5, Mark Hallett1. 1. Human Motor Control Section National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda Maryland USA. 2. Facultad de Medicina Clínica Alemana Universidad del Desarrollo Santiago Chile. 3. Office of the Clinical Director National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda Maryland USA. 4. Wilmington Veterans Administration Medical Center Wilmington Delaware USA. 5. Parkinson's Disease Clinic, Office of the Clinical Director National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda Maryland USA.
Abstract
BACKGROUND: Essential tremor is a common movement disorder, characterized by 4-12 Hz tremor of the hands and arms that can affect many activities of daily living. It has been reported by patients that when performing tasks bimanually their tremor is reduced, but why this happens is unknown. OBJECTIVES: We measured patients' tremors in different conditions when performed with 1 hand and 2 hands to observe if bimanual task performance changes the characteristics of the tremor. METHODS: A total of 10 patients with essential tremor participated in the study. Electromyographic electrodes were attached bilaterally to the wrist flexor and extensor muscles, and accelerometers were attached to the dorsum of the hands. For each condition, holding a cup, wingbeat, and extending both arms up, data were collected with a single hand and bimanually with the hands touching. RESULTS: When the hands were touching, there was a significant decrease in both accelerometric and electromyographic power at the tremor frequency. In addition, there was a decrease in coherence between accelerometer and electromyography on the same side. There was no change in the tremor frequency. CONCLUSIONS: Tremor amplitude does decrease when the hands are together. Together, the characteristics underlying the decrease in tremor amplitude may indicate a decrease in power of the central oscillator driving the tremor, which we speculate is attributed to the differences in unimanual and bimanual motor control. However, given the small sample size, we note that future hypothesis-driven studies with an a priori power analysis will be required to further explore this phenomenon.
BACKGROUND: Essential tremor is a common movement disorder, characterized by 4-12 Hz tremor of the hands and arms that can affect many activities of daily living. It has been reported by patients that when performing tasks bimanually their tremor is reduced, but why this happens is unknown. OBJECTIVES: We measured patients' tremors in different conditions when performed with 1 hand and 2 hands to observe if bimanual task performance changes the characteristics of the tremor. METHODS: A total of 10 patients with essential tremor participated in the study. Electromyographic electrodes were attached bilaterally to the wrist flexor and extensor muscles, and accelerometers were attached to the dorsum of the hands. For each condition, holding a cup, wingbeat, and extending both arms up, data were collected with a single hand and bimanually with the hands touching. RESULTS: When the hands were touching, there was a significant decrease in both accelerometric and electromyographic power at the tremor frequency. In addition, there was a decrease in coherence between accelerometer and electromyography on the same side. There was no change in the tremor frequency. CONCLUSIONS: Tremor amplitude does decrease when the hands are together. Together, the characteristics underlying the decrease in tremor amplitude may indicate a decrease in power of the central oscillator driving the tremor, which we speculate is attributed to the differences in unimanual and bimanual motor control. However, given the small sample size, we note that future hypothesis-driven studies with an a priori power analysis will be required to further explore this phenomenon.
Authors: T A Zesiewicz; R J Elble; E D Louis; G S Gronseth; W G Ondo; R B Dewey; M S Okun; K L Sullivan; W J Weiner Journal: Neurology Date: 2011-10-19 Impact factor: 9.910
Authors: Kailash P Bhatia; Peter Bain; Nin Bajaj; Rodger J Elble; Mark Hallett; Elan D Louis; Jan Raethjen; Maria Stamelou; Claudia M Testa; Guenther Deuschl Journal: Mov Disord Date: 2017-11-30 Impact factor: 10.338
Authors: Eduardo Rocon; Juan Álvaro Gallego; Juan Manuel Belda-Lois; Julián Benito-León; José Luis Pons Journal: Tremor Other Hyperkinet Mov (N Y) Date: 2012-10-10