M Lukács1, L Vécsei, S Beniczky. 1. Department of Neurology, Miskolc Health Center, Kórház u. 1, H-3520 Miskolc, Hungary. mikluk33@hotmail.com
Abstract
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. SIGNIFICANCE: Our findings furnish further insight into the pathophysiology of the motor deficit following a stroke.
OBJECTIVE: Previous studies have revealed a loss of functioning motor units in strokepatients. 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. METHODS: Forty-five strokepatients 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. RESULTS: 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. CONCLUSIONS: 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. SIGNIFICANCE: Our findings furnish further insight into the pathophysiology of the motor deficit following a stroke.
Authors: Xiaoyan Li; Ales Holobar; Marco Gazzoni; Roberto Merletti; William Zev Rymer; Ping Zhou Journal: IEEE Trans Biomed Eng Date: 2014-11-07 Impact factor: 4.538