Burleigh A, Horak F, Nutt J, Frank J
Dow Neurological Sciences Institute of GSH & MC, Portland, OR 97209-1595, USA.
Can J Neurol Sci. 1995 Nov;22(4):280-5. doi: 10.1017/s0317167100039470.
We have quantified the effects of levodopa treatment in Parkinsonian subjects during maintained stance.
Electromyographic muscle activity during quiet stance was assessed in subjects with Parkinson's disease, who exhibited a fluctuating response to levodopa, and in age-matched control subjects. Stance stability was also assessed from mean displacement and velocity of the center of pressure excursions during stance.
Lower extremity and trunk muscles showed high amplitude activity in all Parkinson's subjects when "off", and a 4-5 Hz tremor in three of these subjects. When "on", the amplitude of muscle activity was reduced in the distal muscles more than the proximal, while tremor was suppressed in all muscles. Corresponding to the excessive muscle activity, the Parkinson's subjects had increased velocity and variability of velocity in the anterior-posterior center of foot pressure excursions, but the mean displacement of the center of pressure excursion was not different from the controls. The velocity of center of pressure excursions in the Parkinson's subjects "on", approached those of the control subjects suggesting that the excessive distal muscle amplitude and tremor contributed to the high velocity of the center of pressure.
These findings suggest that dopaminergic systems are involved in the regulation of muscle tone during stance. Depletion of dopaminergic transmission results in increased muscle tone and tremor in the lower extremities which may contribute to changes in posture and stability.
我们已对帕金森病患者在维持站立期间左旋多巴治疗的效果进行了量化。
对帕金森病患者（其对左旋多巴表现出波动反应）以及年龄匹配的对照受试者在安静站立期间的肌电图肌肉活动进行评估。还从站立期间压力中心偏移的平均位移和速度来评估站立稳定性。
所有帕金森病患者在“关”期时下肢和躯干肌肉显示出高振幅活动，其中三名患者出现4 - 5赫兹的震颤。在“开”期时，远端肌肉的肌肉活动振幅比近端肌肉降低得更多，同时所有肌肉的震颤均受到抑制。与过度的肌肉活动相对应，帕金森病患者在足压力前后中心偏移的速度和速度变异性增加，但压力中心偏移的平均位移与对照组无差异。帕金森病患者“开”期时压力中心偏移的速度接近对照受试者，这表明远端肌肉振幅过高和震颤导致了压力中心的高速度。
这些发现表明多巴胺能系统参与了站立期间肌肉张力的调节。多巴胺能传递的耗竭导致下肢肌肉张力增加和震颤，这可能导致姿势和稳定性的改变。
