Related Experiment Videos
Determinants of physiologic tremor in a large normal population
J Raethjen1, F Pawlas, M Lindemann
1Department of Neurology, University of Kiel, Niemannsweg 147, 24105, Kiel, Germany.
Summary
Physiological tremor (PT) is mainly determined by limb mechanics, with a central component present in about one-third of individuals. Age does not affect tremor frequency, and sex influence is indirect, mediated by hand size.
Area of Science:
- Neuroscience
- Biomechanics
- Human Physiology
Background:
- Physiological tremor (PT) generation involves peripheral mechanical factors and central mechanisms.
- Subject attributes like age and sex may influence PT, but quantification in large populations is needed.
Purpose of the Study:
- To quantify the influence of peripheral mechanical factors and subject attributes on physiological tremor in a large, normal population.
- To investigate the role of central mechanisms in physiological tremor.
Main Methods:
- Measured hand and finger tremors in 117 normal subjects (20-94 years) using accelerometry and surface EMG.
- Recorded tremors in various postural positions and with added inertia.
- Assessed hand volume and grip force.
Main Results:
- Hand tremor frequency (mean 7.7 Hz) decreased with added inertia (mean 5.2 Hz) and correlated negatively with hand volume.
- Finger tremor exhibited distinct frequency bands (1-4, 6-11, 15-30 Hz) related to arm, hand, and finger resonance.
- EMG synchronization indicated a central PT component in ~33% of subjects, unaffected by peripheral mechanical changes.
- Age did not significantly influence tremor frequency; sex had a slight but significant effect, mediated by hand volume.
Conclusions:
- Peripheral mechanical properties, particularly limb resonance, are the primary determinants of physiological tremor.
- A central component of PT exists in approximately one-third of the normal population.
- Tremor frequency is not age-dependent, and the influence of sex is indirect, linked to hand size.