Relationship Between Muscle Tone and Elasticity: Simultaneous Quantitative Assessment Using Train-of-Four Monitoring...

Area of Science:

• Musculoskeletal Medicine
• Anesthesiology
• Biomedical Engineering

Background:

• Non-invasive muscle elasticity and tone assessment is vital in musculoskeletal medicine.
• Shear wave elastography (SWE) quantifies muscle elasticity, while train-of-four (TOF) monitoring assesses muscle tone during neuromuscular blockade.

Purpose of the Study:

• To investigate the relationship between muscle elasticity and tone during anesthesia induction.
• To evaluate the utility of continuous SWE (C-SWE) and TOF monitoring in assessing these parameters.

Main Methods:

• Fifteen patients undergoing general anesthesia with rocuronium were recruited.
• Muscle elasticity of the vastus lateralis was measured using C-SWE.
• Muscle tone was evaluated using TOF monitoring before and during complete muscle relaxation (TOF ratio = 0).

Main Results:

• Mean shear wave velocity (SWV) significantly decreased from 5.0 ± 0.4 m/s to 3.1 ± 0.3 m/s (p < 0.0001).
• A significant negative correlation was found between baseline SWV and the degree of SWV reduction (r = -0.728, p = 0.011).
• No correlations were observed between SWV and demographic factors.

Conclusions:

• C-SWE and TOF monitoring are reliable for assessing muscle elasticity and tone during general anesthesia.
• Higher baseline muscle tone correlates with a greater reduction in elasticity upon relaxation.
• Findings support C-SWE's clinical application for intraoperative muscle function assessment.