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Updated: Aug 6, 2025
Manual Muscle Testing: A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients
Published on: April 12, 2011
Quantitative muscle MRI displays clinically relevant myostructural abnormalities in long-term ICU-survivors: a
R Rehmann1, E Enax-Krumova2, C H Meyer-Frießem3
1Department of Neurology, BG-University Hospital Bergmannsheil gGmbH, Ruhr-University Bochum, Bürkle-de-La-Camp-Platz 1, 44789, Bochum, Germany. Robert.Rehmann@rub.de.
Background:
Long-term data on ICU-survivors reveal persisting sequalae and a reduced quality-of-life even after years. Major complaints are neuromuscular dysfunction due to Intensive care unit acquired weakness (ICUAW). Quantitative MRI (qMRI) protocols can quantify muscle alterations in contrast to standard qualitative MRI-protocols.
Methods:
Using qMRI, the aim of this study was to analyse persisting myostructural abnormalities in former ICU patients compared to controls and relate them to clinical assessments. The study was conducted as a cohort/case-control study. Nine former ICU-patients and matched controls were recruited (7 males; 54.8y ± 16.9; controls: 54.3y ± 11.1). MRI scans were performed on a 3T-MRI including a mDTI, T2 mapping and a mDixonquant sequence. Water T2 times, fat-fraction and mean values of the eigenvalue (λ1), mean diffusivity (MD), radial diffusivity (RD) and fractional anisotropy (FA) were obtained for six thigh and seven calf muscles bilaterally. Clinical assessment included strength testing, electrophysiologic studies and a questionnaire on quality-of-life (QoL). Study groups were compared using a multivariate general linear model. qMRI parameters were correlated to clinical assessments and QoL questionnaire using Pearson´s correlation.
Results:
qMRI parameters were significantly higher in the patients for fat-fraction (p < 0.001), water T2 time (p < 0.001), FA (p = 0.047), MD (p < 0.001) and RD (p < 0.001). Thighs and calves showed a different pattern with significantly higher water T2 times only in the calves. Correlation analysis showed a significant negative correlation of muscle strength (MRC sum score) with FA and T2-time. The results were related to impairment seen in QoL-questionnaires, clinical testing and electrophysiologic studies.
Conclusion:
qMRI parameters show chronic next to active muscle degeneration in ICU survivors even years after ICU therapy with ongoing clinical relevance. Therefore, qMRI opens new doors to characterize and monitor muscle changes of patients with ICUAW. Further, better understanding on the underlying mechanisms of the persisting complaints could contribute the development of personalized rehabilitation programs.
Insights
Quantitative MRI reveals chronic muscle degeneration in ICU survivors, impacting quality of life years after intensive care unit (ICU) stays. These findings highlight the clinical relevance of ICUAW and inform personalized rehabilitation strategies.
Area of Science:
- Medical Imaging
- Neurology
- Rehabilitation Medicine
Background:
- Intensive care unit (ICU) survivors often experience long-term neuromuscular dysfunction, termed Intensive Care Unit Acquired Weakness (ICUAW), significantly reducing quality of life.
- Standard MRI protocols are qualitative; quantitative MRI (qMRI) offers objective measurement of muscle alterations.
Purpose of the Study:
- To analyze persistent myostructural abnormalities in former ICU patients using qMRI.
- To correlate these abnormalities with clinical assessments and quality of life.
Main Methods:
- A cohort/case-control study involving nine former ICU patients and matched controls.
- Utilized 3T-MRI with diffusion tensor imaging (mDTI), T2 mapping, and mDixonquant sequences to obtain parameters like fat-fraction and diffusivity.
- Clinical assessments included strength testing, electrophysiology, and quality-of-life questionnaires.
Main Results:
- Former ICU patients exhibited significantly higher fat-fraction, water T2 time, fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) compared to controls.
- Muscle strength negatively correlated with FA and T2 time, indicating a link between qMRI parameters and functional deficits.
- Abnormalities were observed in both thigh and calf muscles, with distinct patterns for water T2 times.
Conclusions:
- qMRI demonstrates ongoing muscle degeneration in ICU survivors years post-therapy, with significant clinical relevance.
- qMRI provides a valuable tool for characterizing and monitoring muscle changes in ICUAW.
- Understanding these persistent changes can guide the development of personalized rehabilitation programs for ICU survivors.
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