Raethjen J, Pawlas F, Lindemann M, Wenzelburger R, Deuschl G
Department of Neurology, University of Kiel, Niemannsweg 147, 24105, Kiel, Germany.
Clin Neurophysiol. 2000 Oct;111(10):1825-37. doi: 10.1016/s1388-2457(00)00384-9.
It has been well established that peripheral mechanical resonant factors as well as central mechanisms may play a role in the generation of physiological tremor (PT). Furthermore it has been postulated that subject's attributes like age and sex might influence PT. The present study was designed to quantify these influences on PT in a large normal population.
Physiological hand and finger tremors were measured in a group of 117 normal subjects between 20 and 94 years of age using accelerometry and surface EMG recordings from the forearm flexor and extensor muscles. The hand tremor was measured in a postural position with and without weight, and the finger tremor was recorded with the arm outstretched, forearm supported and hand supported. Hand volume and grip force were measured in each subject.
Hand tremor frequency (mean 7.7 Hz) was reduced significantly by added inertia (mean 5.2 Hz) and it was negatively correlated with hand volume while there was no correlation with grip force. Finger tremor showed, subject to the arm position, maximally 3 and at least two distinct frequency bands (1-4, 6-11 and 15-30 Hz) reflecting the resonance frequencies of the whole arm, the hand and the finger, respectively. A significant EMG peak was found in 50-80% of the recordings. This EMG synchronization gave rise to a corresponding accelerometer peak or a significant EMG-EMG coherence in about one-third of the population indicating a central component of PT because its frequency was unaffected by mechanical changes in the periphery. We did not find a significant influence of age on the tremor frequency, while the sex of the subjects slightly but significantly changed the frequency range of hand tremor. Multiple partial correlations revealed, however, that the only direct influence on hand tremor frequency is the hand volume indicating that the influence of sex on hand tremor frequency is an indirect effect produced by the significantly larger hands of male subjects.
In conclusion, the main determinants of PT are the mechanical properties of the oscillating limb. Apart from the dominating peripheral resonance mechanism we found indications of an additional central component of PT in about one-third of the normal population. There was no age dependence of tremor frequency and it was shown that the influence of the subjects' sex on tremor frequency only represents an indirect mechanical effect.
外周机械共振因素以及中枢机制在生理性震颤（PT）的产生中可能发挥作用，这一点已得到充分证实。此外，有人推测年龄和性别等受试者属性可能会影响PT。本研究旨在量化这些因素对大量正常人群PT的影响。
使用加速度计以及来自前臂屈肌和伸肌的表面肌电图记录，对117名年龄在20至94岁之间的正常受试者的手部和手指生理性震颤进行测量。在有重量和无重量的姿势下测量手部震颤，在手臂伸展、前臂支撑和手部支撑的情况下记录手指震颤。测量每个受试者的手部体积和握力。
增加惯性后手部震颤频率（平均7.7Hz）显著降低（平均5.2Hz），且与手部体积呈负相关，与握力无相关性。手指震颤在不同手臂位置下，最多显示3个且至少有两个不同的频带（1 - 4Hz、6 - 11Hz和15 - 30Hz），分别反映整个手臂、手部和手指的共振频率。在50% - 80%的记录中发现了明显的肌电图峰值。这种肌电图同步在约三分之一的人群中产生了相应的加速度计峰值或显著的肌电图 - 肌电图相干性，表明PT存在中枢成分，因为其频率不受外周机械变化的影响。我们未发现年龄对震颤频率有显著影响，而受试者的性别略微但显著地改变了手部震颤的频率范围。然而，多重偏相关分析显示，对手部震颤频率的唯一直接影响是手部体积，这表明性别对手部震颤频率的影响是男性受试者手部明显较大所产生的间接效应。
总之，PT的主要决定因素是振荡肢体的机械特性。除了占主导地位的外周共振机制外，我们在约三分之一的正常人群中发现了PT存在额外中枢成分的迹象。震颤频率不存在年龄依赖性，并且表明受试者性别对震颤频率的影响仅代表一种间接的机械效应。
