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Abstract
Background Evaluation of the structural integrity and functional excitability of the corticospinal tract (CST) is likely to be important in predicting motor recovery after stroke. Previous reports are inconsistent regarding a possible link between CST structure and CST function in this setting. This study aims to investigate the structure‒function relationship of the CST at the acute phase of stroke (<7 days).
Methods We enrolled 70 patients who had an acute ischaemic stroke with unilateral upper extremity (UE) weakness. They underwent a multimodal assessment including clinical severity (UE Fugl Meyer at day 7 and 3 months), MRI to evaluate the CST lesion load and transcranial magnetic stimulation to measure the maximum amplitude of motor evoked potential (MEP).
Results A cross-sectional lesion load above 87% predicted the absence of MEPs with an accuracy of 80.4%. In MEP-positive patients, the CST structure/function relationship was bimodal with a switch from a linear relationship (rho=−0.600, 95% CI −0.873; −0.039, p<0.03) for small MEP amplitudes (<0.703 mV) to a non-linear relationship for higher MEP amplitudes (p=0.72). In MEP-positive patients, recovery correlated with initial severity. In patients with a positive MEP <0.703 mV but not in patients with an MEP ≥0.703 mV, MEP amplitude was an additional independent predictor of recovery. In MEP-negative patients, we failed to identify any factor predicting recovery.
Conclusion This large multimodal study on the structure/function of the CST and stroke recovery proposes a paradigm change for the MEP-positive patients phenotypes and refines the nature of the link between structural integrity and neurophysiological function, with implications for study design and prognostic information.
- stroke
- recovery
- motor evoked potential
- corticospinal tract
Data availability statement
Data are available upon reasonable request. Request of our data necessitate specific local ethic committee approval and to follow GDPR rules.
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Data availability statement
Data are available upon reasonable request. Request of our data necessitate specific local ethic committee approval and to follow GDPR rules.
Footnotes
Contributors LD: data collection and analysis and drafting of manuscript. CR: study design, data analysis and drafting of manuscript. ER and PP: study design, drafting and revision of the manuscript. J-CL: data collection and manuscript revision. TC, AW, RV and DG: data collection and data analysis. F-XL and MD: statistical analysis.
CR acted as the guarantor for the integrity of the work.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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