Lukács M, Vécsei L, Beniczky S
Department of Neurology, Miskolc Health Center, Kórház u. 1, H-3520 Miskolc, Hungary.
Clin Neurophysiol. 2008 Nov;119(11):2555-8. doi: 10.1016/j.clinph.2008.08.005. Epub 2008 Sep 21.
Previous studies have revealed a loss of functioning motor units in stroke patients. However, it remained unclear whether the motor units are affected randomly or in some specific pattern. We assessed whether there is a selective loss of the large (high recruitment threshold) or the small (low recruitment threshold) motor units following a stroke.
Forty-five stroke patients and 40 healthy controls participated in the study. Macro-EMG was recorded from the abductor digiti minimi muscle at two levels of force output (low and high). The median macro motor unit potential (macro-MUP) amplitude on the paretic side was compared with those on the unaffected side and in the controls.
In the control group and on the unaffected side, the macro-MUPs were significantly larger at the high force output than at the low one. However, on the paretic side the macro-MUPs at the high force output had the same amplitude as those recorded at the low force output. These changes correlated with the severity of the paresis.
Following a stroke, there is a selective functional loss of the large, high-threshold motor units. These changes are related to the severity of the symptoms.
Our findings furnish further insight into the pathophysiology of the motor deficit following a stroke.
以往研究揭示了中风患者存在功能失调的运动单位缺失。然而，运动单位是随机受到影响还是存在某种特定模式仍不明确。我们评估了中风后大（高募集阈值）运动单位或小（低募集阈值）运动单位是否存在选择性缺失。
45名中风患者和40名健康对照者参与了本研究。在两种力输出水平（低和高）下，从小指展肌记录宏肌电图。将患侧的宏运动单位电位（macro-MUP）中位振幅与未受影响侧及对照组进行比较。
在对照组和未受影响侧，高力输出时的宏MUP明显大于低力输出时。然而，在患侧，高力输出时的宏MUP振幅与低力输出时记录的相同。这些变化与轻瘫的严重程度相关。
中风后，存在大的、高阈值运动单位的选择性功能丧失。这些变化与症状的严重程度有关。
我们的研究结果为中风后运动功能障碍的病理生理学提供了进一步的见解。
