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Wilcox M, Dos Santos Canas L, Hargunani R, Tidswell T, Brown H, Modat M, Phillips JB, Ourselin S, Quick T. Volumetric MRI is a promising outcome measure of muscle reinnervation. Sci Rep 2021; 11:22433. [PMID: 34789795 PMCID: PMC8599480 DOI: 10.1038/s41598-021-01342-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 10/18/2021] [Indexed: 11/09/2022] Open
Abstract
The development of outcome measures that can track the recovery of reinnervated muscle would benefit the clinical investigation of new therapies which hope to enhance peripheral nerve repair. The primary objective of this study was to assess the validity of volumetric Magnetic Resonance Imaging (MRI) as an outcome measure of muscle reinnervation by testing its reproducibility, responsiveness and relationship with clinical indices of muscular function. Over a 3-year period 25 patients who underwent nerve transfer to reinnervate elbow flexor muscles were assessed using intramuscular electromyography (EMG) and MRI (median post-operative assessment time of 258 days, ranging from 86 days pre-operatively to 1698 days post- operatively). Muscle power (Medical Research Council (MRC) grade) and Stanmore Percentage of Normal Elbow Assessment (SPONEA) assessment was also recorded for all patients. Sub-analysis of peak volitional force (PVF), muscular fatigue and co-contraction was performed in those patients with MRC > 3. The responsiveness of each parameter was compared using Pearson or Spearman correlation. A Hierarchical Gaussian Process (HGP) was implemented to determine the ability of volumetric MRI measurements to predict the recovery of muscular function. Reinnervated muscle volume per unit Body Mass Index (BMI) demonstrated good responsiveness (R2 = 0.73, p < 0.001). Using the temporal and muscle volume per unit BMI data, a HGP model was able to predict MRC grade and SPONEA with a mean absolute error (MAE) of 0.73 and 1.7 respectively. Muscle volume per unit BMI demonstrated moderate to good positive correlations with patient reported impairments of reinnervated muscle; co- contraction (R2 = 0.63, p = 0.02) and muscle fatigue (R2 = 0.64, p = 0.04). In summary, volumetric MRI analysis of reinnervated muscle is highly reproducible, responsive to post-operative time and demonstrates correlation with clinical indices of muscle function. This encourages the view that volumetric MRI is a promising outcome measure for muscle reinnervation which will drive advancements in motor recovery therapy.
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Affiliation(s)
- Matthew Wilcox
- Peripheral Nerve Injury Research Unit, Royal National Orthopaedic Hospital, Stanmore, UK. .,UCL Centre for Nerve Engineering, University College London, London, UK. .,Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK. .,University College London Medical School, London, UK.
| | | | - Rikin Hargunani
- Department of Radiology, Royal National Orthopaedic Hospital, Stanmore, UK
| | - Tom Tidswell
- Department of Clinical Neurophysiology, Royal Free Hospital, London, UK
| | - Hazel Brown
- Peripheral Nerve Injury Research Unit, Royal National Orthopaedic Hospital, Stanmore, UK.,UCL Centre for Nerve Engineering, University College London, London, UK
| | - Marc Modat
- Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - James B Phillips
- UCL Centre for Nerve Engineering, University College London, London, UK.,Department of Pharmacology, UCL School of Pharmacy, University College London, London, UK
| | - Sebastien Ourselin
- Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Tom Quick
- Peripheral Nerve Injury Research Unit, Royal National Orthopaedic Hospital, Stanmore, UK.,UCL Centre for Nerve Engineering, University College London, London, UK
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