Arm function after stroke: Neurophysiological correlates and recovery mechanisms assessed by transcranial magnetic stimulation

Talelli, Penelope; Greenwood, Richard; Rothwell, John C.

doi:10.1016/j.clinph.2006.01.016

Cited by 244 publications

(194 citation statements)

References 135 publications

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“…First, BB is a proximal upper limb muscle with typically high TMS-induced resting motor thresholds (RThs) and thus requires the application of high stimulation intensities (Gerachshenko and Stinear, 2007;Rothwell et al, 1991;Turton et al, 1996;. Second, paretic muscle motor thresholds are increased following stroke (Talelli et al, 2006). Our preliminary experiments confirmed that the combination of those two factors results in a low probability of obtaining MEPs in a relaxed paretic BB.…”

Section: Technical Considerationssupporting

confidence: 70%

Abnormal corticomotor excitability assessed in biceps brachii preceding pronator contraction post-stroke

Gerachshenko¹,

Rymer²,

Stinear³

2008

Clinical Neurophysiology

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Objective-To assess corticomotor excitability (CM) of the antagonist biceps brachii (BB) poststroke in preparation for pronator contraction. In healthy subjects, we previously demonstrated that prior to pronator contraction CM excitability of the antagonist BB was suppressed.Methods-Transcranial magnetic stimulation (TMS) was used to assess pre-contraction changes in motor evoked potential (MEP) amplitude of the BB, when BB was acting either as an antagonist or an agonist. TMS was applied 100−200 ms prior to rhythmic isometric BB or pronator contractions in chronic stroke survivors and age/gender matched healthy control subjects.Results-Prior to pronator contraction, MEPs in BB were elicited in the stroke group but were absent in healthy controls indicating that CM excitability of the antagonist BB was increased poststroke. The extent of the abnormal increase in excitability positively correlated with the extent of upper limb motor impairment.Conclusions-Our results suggest that an alteration of cortical control mechanisms regulating motor excitability of the antagonist BB may contribute to the impairment of upper limb motor coordination post-stroke.Significance-This study offers a unique approach to study the potential for a cortical origin of post-stroke motor discoordination.

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Section: Technical Considerationssupporting

confidence: 70%

Abnormal corticomotor excitability assessed in biceps brachii preceding pronator contraction post-stroke

Gerachshenko¹,

Rymer²,

Stinear³

2008

Clinical Neurophysiology

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“…In contrast, subcortical strokes are less likely to induce changes in excitability of cortical neurons, but instead cause interruption to corticospinal fibres, seen as increase in the rMT and decrease in the MEP amplitude. Again, possible resolution in the early recovery stage may explain the rapid changes in CSE in the acute stage [29]. Although, the apparent CSE recovery seen in figure 1 appears strong, some previous studies have concluded that the rMT is influenced by multiple structural and functional characteristics of both cortical and spinal neurons negatively affecting its ability to act as a reliable biomarker regarding inter-hemispheric differences in excitability [7,19].…”

Section: Discussionmentioning

confidence: 91%

Longitudinal study on modulated corticospinal excitability throughout recovery in supratentorial stroke

Julkunen

Könönen

Määttä

et al. 2016

Neuroscience Letters

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Longitudinal study on modulated corticospinal excitability throughout recovery in supratentorial stroke, Neuroscience Letters http://dx.doi.org/10. 1016/j.neulet.2016.02.014 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractCorticospinal excitability (CSE) is modulated by stroke-induced lesions affecting the brain. This modulation is known to be dependent on the timing of the evaluation, and strongest abnormalities are often found in the acute stage. Our study aimed to characterize changes in CSE asymmetry between the affected and the unaffected hemisphere (AH and UH) during the first month after stroke onset and at 6 month follow-up. Neuronavigated transcranial magnetic stimulation (nTMS) was used to assess the CSE of the abductor pollicis brevis (APB) muscle of the hand and tibialis anterior (TA) muscle of the leg in 16 patients over 5 time-points. AH excitability recovered significantly during 6 months, whereas interhemispheric asymmetry remained significant up to 1 month post-stroke in the APB muscle. Greater initial CSE was associated with good motor function at 6 months. The motor cortical excitatory recovery initiated within week of the stroke and was most prominent within 1 month after stroke onset. Lesion size correlated with CSE of the UH at 10 days, while overall severity of the symptoms correlated inversely with CSE of the AH. This study demonstrates the quick improvement in the CSE via estimation of interhemispheric asymmetry; however, the recovery in the asymmetry continues to normalize even after reaching the threshold for normal values in CSE.

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“…7 Previous studies evaluating motor cortex excitability in the acute and subacute stages after stroke 1,3,[13][14][15][16][17][18] showed decreased resting SICI in the ipsilesional M1, an abnormality that may normalize in the chronic stage. 15,[17][18][19] Movement-related changes in SICI in stroke patients intending to move the paretic hand have not been investigated. Here, we hypothesized that dynamic modulation of premovement SICI, as described in healthy subjects, [7][8][9] would be impaired in the ipsilesional M1 of chronic stroke patients moving the paretic hand.…”

mentioning

confidence: 99%

Deficient intracortical inhibition (SICI) during movement preparation after chronic stroke

Hummel

Steven²,

Hoppe³

et al. 2009

Neurology

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Arm function after stroke: Neurophysiological correlates and recovery mechanisms assessed by transcranial magnetic stimulation

Cited by 244 publications

References 135 publications

Abnormal corticomotor excitability assessed in biceps brachii preceding pronator contraction post-stroke

Abnormal corticomotor excitability assessed in biceps brachii preceding pronator contraction post-stroke

Longitudinal study on modulated corticospinal excitability throughout recovery in supratentorial stroke

Deficient intracortical inhibition (SICI) during movement preparation after chronic stroke

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