Corticospinal and Reticulospinal-Associated Measures in Chronic Ischemic Stroke: Associations with Upper Limb Function
- 1Department of Neurology, Institute of Neurosciences Kolkata, Kolkata, India
Abstract
Background: Corticospinal tract (CST) damage is the main cause of post-stroke motor impairment. Whilst the output of the reticulospinal tract (RST) is reportedly upregulated, its relation to CST damage post-stroke is unclear. We assessed CST integrity using transcranial magnetic stimulation and RST activity using the StartReact paradigm in chronic ischemic stroke and examined their inter-relationship and associations with upper-limb impairment. Methods: We included 80 patients with chronic ischemic stroke and 15 age-matched healthy controls (HCs). CST function was quantified using the resting motor threshold asymmetry index (RMT-AI); RST function was measured by the StartReact effect (visual-auditory minus visual-startle reaction time) during isometric wrist flexion. Impairment was assessed with the Fugl-Meyer Assessment-Upper Extremity (FMA-UE) and affected-side grip strength, with FDR-corrected correlations. Results: Higher RMT-AI was associated with lower FMA-UE (r -0.46, p 0.0038) and weaker grip (rho -0.43, p 0.0065). A larger StartReact effect showed the same pattern (rho -0.35, p 0.0095, FMA-UE; rho -0.41, p 0.00195, grip). All correlations remained significant after FDR correction. RMT-AI and the StartReact effect were uncorrelated (r 0.05, p 0.792). The StartReact effect did not differ between sides (p 0.631) or between patients and HCs (p 0.342) but was larger in patients with FMA-UE less than or equal to median than in HCs (p 0.025), without a side difference (p 0.143). Conclusions: Greater impairment was associated with greater CST damage and RST activity, possibly reflecting cortico-reticular fibre damage. CST and RST measures were unrelated, suggesting cortical input to the reticular formation beyond M1. Severely impaired patients showed greater bilateral reticulospinal involvement.
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BibTeX
@misc{bayen2026corticospinal,
title = {{Corticospinal and Reticulospinal-Associated Measures in Chronic Ischemic Stroke: Associations with Upper Limb Function}},
author = {A. B. Bayen and S. Sarkar and S. Saha and U. Bakshi and C. Das and A. Shobhana and A. Ghosal and S. Mukherjee and S. S. Anand and A. Pal and A. Chatterjee and S. Gangopadhyay and S. Dey and P. Basu and B. Zaaimi and M. R. Baker and S. N. Baker and H. Kumar and S. Choudhury},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.26.26365898},
url = {https://www.medrxiv.org/content/10.64898/2026.10.26.26365898v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Corticospinal and Reticulospinal-Associated Measures in Chronic Ischemic Stroke: Associations with Upper Limb Function
AU - A. B. Bayen
AU - S. Sarkar
AU - S. Saha
AU - U. Bakshi
AU - C. Das
AU - A. Shobhana
AU - A. Ghosal
AU - S. Mukherjee
AU - S. S. Anand
AU - A. Pal
AU - A. Chatterjee
AU - S. Gangopadhyay
AU - S. Dey
AU - P. Basu
AU - B. Zaaimi
AU - M. R. Baker
AU - S. N. Baker
AU - H. Kumar
AU - S. Choudhury
PY - 2026
DA - 2026/10/26
PB - medRxiv
DO - 10.64898/2026.10.26.26365898
UR - https://www.medrxiv.org/content/10.64898/2026.10.26.26365898v1
AB - Background: Corticospinal tract (CST) damage is the main cause of post-stroke motor impairment. Whilst the output of the reticulospinal tract (RST) is reportedly upregulated, its relation to CST damage post-stroke is unclear. We assessed CST integrity using transcranial magnetic stimulation and RST activity using the StartReact paradigm in chronic ischemic stroke and examined their inter-relationship and associations with upper-limb impairment. Methods: We included 80 patients with chronic ischemic stroke and 15 age-matched healthy controls (HCs). CST function was quantified using the resting motor threshold asymmetry index (RMT-AI); RST function was measured by the StartReact effect (visual-auditory minus visual-startle reaction time) during isometric wrist flexion. Impairment was assessed with the Fugl-Meyer Assessment-Upper Extremity (FMA-UE) and affected-side grip strength, with FDR-corrected correlations. Results: Higher RMT-AI was associated with lower FMA-UE (r -0.46, p 0.0038) and weaker grip (rho -0.43, p 0.0065). A larger StartReact effect showed the same pattern (rho -0.35, p 0.0095, FMA-UE; rho -0.41, p 0.00195, grip). All correlations remained significant after FDR correction. RMT-AI and the StartReact effect were uncorrelated (r 0.05, p 0.792). The StartReact effect did not differ between sides (p 0.631) or between patients and HCs (p 0.342) but was larger in patients with FMA-UE less than or equal to median than in HCs (p 0.025), without a side difference (p 0.143). Conclusions: Greater impairment was associated with greater CST damage and RST activity, possibly reflecting cortico-reticular fibre damage. CST and RST measures were unrelated, suggesting cortical input to the reticular formation beyond M1. Severely impaired patients showed greater bilateral reticulospinal involvement.
ER -