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The unsolved role of heightened connectivity from the unaffected hemisphere to paretic arm muscles in chronic stroke

Hammerbeck, U; Hoad, D; Greenwood, R; Rothwell, JC; (2019) The unsolved role of heightened connectivity from the unaffected hemisphere to paretic arm muscles in chronic stroke. Clinical Neurophysiology , 130 (5) pp. 781-788. 10.1016/j.clinph.2019.02.018. Green open access

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Rothwell_TMS Clin NeurophysReview vs2.pdf - Accepted Version

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Abstract

Objective: Ipsilateral connectivity from the non-stroke hemisphere to paretic arm muscles appears to play little role in functional recovery, which instead depends on contralateral connectivity from the stroke hemisphere. Yet the incidence of ipsilateral projections in stroke survivors is often reported to be higher than normal. We tested this directly using a sensitive measure of connectivity to proximal arm muscles. / Method: TMS of the stroke and non-stroke motor cortex evoked responses in pre-activated triceps and deltoid muscles of 17 stroke survivors attending reaching training. Connectivity was defined as a clear MEP or a short-latency silent period in ongoing EMG in ≥ 50% of stimulations. We measured reaching accuracy at baseline, improvement after training and upper limb Fugl-Meyer (F-M) score. / Results: Incidence of ipsilateral connections to triceps (47%) and deltoid (58%) was high, but unrelated to baseline reaching accuracy and F-M scores. Instead, these were related to contralateral connectivity from the stroke hemisphere. Absolute but not proportional improvement after training was greater in patients with ipsilateral responses. / Conclusions: Despite enhanced ipsilateral connectivity, arm function and learning was related most strongly to contralateral pathway integrity from the stroke hemisphere. / Significance: Further work is needed to decipher the role of ipsilateral connections.

Type: Article
Title: The unsolved role of heightened connectivity from the unaffected hemisphere to paretic arm muscles in chronic stroke
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.clinph.2019.02.018
Publisher version: https://doi.org/10.1016/j.clinph.2019.02.018
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Stroke, Transcranial magnetic stimulation, Ipsilateral, Corticospinal connection, Proximal upper limb
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Clinical and Movement Neurosciences
URI: https://discovery.ucl.ac.uk/id/eprint/10073865
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