Publications

• Resting tone and stiffness of the Longissimus Thoracis and Lumbar Multifidus are significantly associated with trunk control and global disability in acute stroke survivors.
• Among posterior trunk muscles, resting tone and stiffness of the Longissimus Thoracis showed the strongest correlation with trunk stability, reflecting its strategic anatomical role.
• This study is among the first to quantify resting-state viscoelastic properties of the Longissimus Thoracis and Lumbar Multifidus muscles in acute stroke survivors, providing potential targets for early rehabilitation strategies.

Background: Trunk control is an early predictor of functional and motor recovery in acute ischemic stroke (AIS). Although changes in muscle tone and stiffness post-stroke are well documented, their relationship with trunk control remains underexplored.

Objective: To identify which trunk muscles’ resting tone and stiffness are most strongly correlated with trunk control in AIS survivors.

Methods: Thirty AIS survivors (time from symptom onset ≤72 hours) were included in this cross-sectional study. Trunk control and global disability were assessed using the Trunk Impairment Scale (TIS) and modified Rankin Scale (mRS), respectively. MyotonPRO® was used to measure tone and stiffness of the Longissimus Thoracis (LT), Lumbar Multifidus (LM), Trapezius (T), and Rectus Femoris (RF) muscles. Pearson’s correlation and multiple linear regression analyses were performed.

Results: TIS scores correlated strongly with LT tone (r = 0.604, p < 0.001), LT stiffness (r = 0.648, p < 0.001), and LM stiffness (r = 0.619, p < 0.001), and moderately with LM tone (r = 0.410, p = 0.012), but not with Trapezius tone (p = 0.092) or RF stiffness (p = 0.305). LT stiffness showed a strong negative correlation with mRS grade (r = -0.648, p < 0.001). Regression analysis identified LT tone (R2 = 0.318, p = 0.008) and LT stiffness (R2 = 0.432, p = 0.001) as significant independent predictors of trunk control.

Conclusions: Resting tone and stiffness of the LT are associated with trunk control and global disability in AIS survivors. Higher LT stiffness predicts better trunk control and lower disability, suggesting its potential as an early marker of functional recovery.

Trial registration: Clinicaltrials.gov (NCT06006988)

Keywords: muscle tone, myotonometer, stroke, trunk control, mechanical properties

Resting tone and stiffness of the Longissimus Thoracis and Lumbar Multifidus muscles are associated with trunk control and global disability in acute ischemic stroke survivors. The Longissimus Thoracis, in particular, shows the strongest relationship with trunk control, suggesting its potential relevance for early rehabilitation strategies. These findings are correlational and require longitudinal studies to determine whether these muscle properties can serve as predictive markers or modifiable therapeutic targets.