Yarrow K, Brown P, Gresty M A, Bronstein A M
MRC Human Movement and Balance Unit, National Hospital for Neurology and Neurosurgery, 8-11 Queen Square, London, WC1N 3BG, UK.
Gait Posture. 2001 Feb;13(1):27-34. doi: 10.1016/s0966-6362(00)00097-7.
Primary orthostatic tremor (OT) consists of rhythmical muscle contractions at a frequency of around 16 Hz, causing discomfort and/or unsteadiness while standing. Diagnosis has hitherto relied on recording Electromyography (EMG) from affected muscles. The main aim of this study was to see if the characteristic postural tremor in OT can be identified with force platforms. We also quantified postural sway in OT patients to assess their degree of objective unsteadiness. Finally, we investigated the time relations between bursts of activity in the various affected muscle groups. Subjects stood on a force platform with concurrent multichannel surface EMG recordings from the lower limbs. Seven patients with clinical and EMG diagnosis of OT were examined and the force platform data compared with those of 21 other neurological patients with postural tremor and eight normal controls. All OT patients had high frequency peaks in power spectra of posturography and EMG recordings (12--16 Hz). No such high frequency activity was evident in patients with Parkinson's disease, cerebellar degenerations, essential tremor or in healthy controls. Additionally, OT patients showed increased sway at low frequencies relative to normal controls, suggesting that the unsteadiness reported by OT patients is at least partly due to increased postural sway. Examination of EMG timing showed fixed patterns of muscle activation when maintaining a quiet stance within but not across OT patients. These data show a high correlation between EMG and posturography and confirm that OT may be diagnosed using short epochs of force platform recordings.
原发性直立性震颤（OT）由频率约为16Hz的节律性肌肉收缩组成，导致站立时不适和/或不稳。迄今为止，诊断主要依靠记录受影响肌肉的肌电图（EMG）。本研究的主要目的是确定是否可以使用测力平台识别OT的特征性姿势性震颤。我们还对OT患者的姿势摆动进行了量化，以评估其客观不稳程度。最后，我们研究了不同受影响肌肉群活动爆发之间的时间关系。受试者站在测力平台上，同时记录下肢的多通道表面肌电图。对7例临床和肌电图诊断为OT的患者进行了检查，并将测力平台数据与另外21例有姿势性震颤的神经科患者及8例正常对照者的数据进行了比较。所有OT患者在姿势描记图和肌电图记录的功率谱中都有高频峰值（12 - 16Hz）。帕金森病、小脑变性、特发性震颤患者或健康对照者均未出现这种高频活动。此外，OT患者相对于正常对照者在低频时摆动增加，这表明OT患者报告的不稳至少部分是由于姿势摆动增加所致。对肌电图时间的检查显示，在保持安静姿势时，OT患者内部存在固定的肌肉激活模式，但不同患者之间不存在。这些数据表明肌电图和姿势描记图之间具有高度相关性，并证实可以使用短时间的测力平台记录来诊断OT。
