Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence
The phenomenon of exaggerated motor overflow is well documented in stroke survivors with spasticity. However, the mechanism underlying the abnormal motor overflow remains unclear. In this study, we aimed to investigate the possible mechanisms behind abnormal motor overflow and its possible relations...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2018-10-01
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| Series: | Frontiers in Neurology |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fneur.2018.00795/full |
| _version_ | 1828741122342518784 |
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| author | Yen-Ting Chen Yen-Ting Chen Shengai Li Shengai Li Elaine Magat Elaine Magat Ping Zhou Ping Zhou Sheng Li Sheng Li |
| author_facet | Yen-Ting Chen Yen-Ting Chen Shengai Li Shengai Li Elaine Magat Elaine Magat Ping Zhou Ping Zhou Sheng Li Sheng Li |
| author_sort | Yen-Ting Chen |
| collection | DOAJ |
| description | The phenomenon of exaggerated motor overflow is well documented in stroke survivors with spasticity. However, the mechanism underlying the abnormal motor overflow remains unclear. In this study, we aimed to investigate the possible mechanisms behind abnormal motor overflow and its possible relations with post-stroke spasticity. 11 stroke patients (63.6 ± 6.4 yrs; 4 women) and 11 healthy subjects (31.18 ± 6.18 yrs; 2 women) were recruited. All of them were asked to perform unilateral isometric elbow flexion at submaximal levels (10, 30, and 60% of maximum voluntary contraction). Electromyogram (EMG) was measured from the contracting biceps (iBiceps) muscle and resting contralateral biceps (cBiceps), ipsilateral flexor digitorum superficialis (iFDS), and contralateral FDS (cFDS) muscles. Motor overflow was quantified as the normalized EMG of the resting muscles. The severity of motor impairment was quantified through reflex torque (spasticity) and weakness. EMG-EMG coherence was calculated between the contracting muscle and each of the resting muscles. During elbow flexion on the impaired side, stroke subjects exhibited significant higher motor overflow to the iFDS muscle compared with healthy subjects (ipsilateral or intralimb motor overflow). Stroke subjects exhibited significantly higher motor overflow to the contralateral spastic muscles (cBiceps and cFDS) during elbow flexion on the non-impaired side (contralateral or interlimb motor overflow), compared with healthy subjects. Moreover, there was significantly high EMG-EMG coherence in the alpha band (6–12 Hz) between the contracting muscle and all other resting muscles during elbow flexion on the non-impaired side. Our results of diffuse ipsilateral and contralateral motor overflow with EMG-EMG coherence in the alpha band suggest subcortical origins of motor overflow. Furthermore, correlation between contralateral motor overflow to contralateral spastic elbow and finger flexors and their spasticity was consistently at moderate to high levels. A high correlation suggests that diffuse motor overflow to the impaired side and spasticity likely share a common pathophysiological process. Possible mechanisms are discussed. |
| first_indexed | 2024-04-13T00:53:59Z |
| format | Article |
| id | doaj.art-1ad57b60aa004e348bcee5e7ddb91c95 |
| institution | Directory Open Access Journal |
| issn | 1664-2295 |
| language | English |
| last_indexed | 2024-04-13T00:53:59Z |
| publishDate | 2018-10-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Neurology |
| spelling | doaj.art-1ad57b60aa004e348bcee5e7ddb91c952022-12-22T03:09:46ZengFrontiers Media S.A.Frontiers in Neurology1664-22952018-10-01910.3389/fneur.2018.00795373523Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG CoherenceYen-Ting Chen0Yen-Ting Chen1Shengai Li2Shengai Li3Elaine Magat4Elaine Magat5Ping Zhou6Ping Zhou7Sheng Li8Sheng Li9Department of Physical Medicine and Rehabilitation, McGovern Medical School, University of Texas Health Science Center – Houston, Houston, TX, United StatesTIRR Research Center, TIRR Memorial Hermann Hospital, Houston, TX, United StatesDepartment of Physical Medicine and Rehabilitation, McGovern Medical School, University of Texas Health Science Center – Houston, Houston, TX, United StatesTIRR Research Center, TIRR Memorial Hermann Hospital, Houston, TX, United StatesDepartment of Physical Medicine and Rehabilitation, McGovern Medical School, University of Texas Health Science Center – Houston, Houston, TX, United StatesTIRR Research Center, TIRR Memorial Hermann Hospital, Houston, TX, United StatesDepartment of Physical Medicine and Rehabilitation, McGovern Medical School, University of Texas Health Science Center – Houston, Houston, TX, United StatesTIRR Research Center, TIRR Memorial Hermann Hospital, Houston, TX, United StatesDepartment of Physical Medicine and Rehabilitation, McGovern Medical School, University of Texas Health Science Center – Houston, Houston, TX, United StatesTIRR Research Center, TIRR Memorial Hermann Hospital, Houston, TX, United StatesThe phenomenon of exaggerated motor overflow is well documented in stroke survivors with spasticity. However, the mechanism underlying the abnormal motor overflow remains unclear. In this study, we aimed to investigate the possible mechanisms behind abnormal motor overflow and its possible relations with post-stroke spasticity. 11 stroke patients (63.6 ± 6.4 yrs; 4 women) and 11 healthy subjects (31.18 ± 6.18 yrs; 2 women) were recruited. All of them were asked to perform unilateral isometric elbow flexion at submaximal levels (10, 30, and 60% of maximum voluntary contraction). Electromyogram (EMG) was measured from the contracting biceps (iBiceps) muscle and resting contralateral biceps (cBiceps), ipsilateral flexor digitorum superficialis (iFDS), and contralateral FDS (cFDS) muscles. Motor overflow was quantified as the normalized EMG of the resting muscles. The severity of motor impairment was quantified through reflex torque (spasticity) and weakness. EMG-EMG coherence was calculated between the contracting muscle and each of the resting muscles. During elbow flexion on the impaired side, stroke subjects exhibited significant higher motor overflow to the iFDS muscle compared with healthy subjects (ipsilateral or intralimb motor overflow). Stroke subjects exhibited significantly higher motor overflow to the contralateral spastic muscles (cBiceps and cFDS) during elbow flexion on the non-impaired side (contralateral or interlimb motor overflow), compared with healthy subjects. Moreover, there was significantly high EMG-EMG coherence in the alpha band (6–12 Hz) between the contracting muscle and all other resting muscles during elbow flexion on the non-impaired side. Our results of diffuse ipsilateral and contralateral motor overflow with EMG-EMG coherence in the alpha band suggest subcortical origins of motor overflow. Furthermore, correlation between contralateral motor overflow to contralateral spastic elbow and finger flexors and their spasticity was consistently at moderate to high levels. A high correlation suggests that diffuse motor overflow to the impaired side and spasticity likely share a common pathophysiological process. Possible mechanisms are discussed.https://www.frontiersin.org/article/10.3389/fneur.2018.00795/fullmotor overflowstrokespasticityEMG-EMG coherencereticulospinal tract |
| spellingShingle | Yen-Ting Chen Yen-Ting Chen Shengai Li Shengai Li Elaine Magat Elaine Magat Ping Zhou Ping Zhou Sheng Li Sheng Li Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence Frontiers in Neurology motor overflow stroke spasticity EMG-EMG coherence reticulospinal tract |
| title | Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence |
| title_full | Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence |
| title_fullStr | Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence |
| title_full_unstemmed | Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence |
| title_short | Motor Overflow and Spasticity in Chronic Stroke Share a Common Pathophysiological Process: Analysis of Within-Limb and Between-Limb EMG-EMG Coherence |
| title_sort | motor overflow and spasticity in chronic stroke share a common pathophysiological process analysis of within limb and between limb emg emg coherence |
| topic | motor overflow stroke spasticity EMG-EMG coherence reticulospinal tract |
| url | https://www.frontiersin.org/article/10.3389/fneur.2018.00795/full |
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