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Exploring Volitional Control and Recovery Strength in Elbow Flexion After Ipsilateral C7 Transfer for C5-6 Brachial Plexus Injury Patients
Ying - Hsuan Lee, MD
1; Johnny Lu, MD
2; Tommy Nai-Jen Chang, MD
3; Chuang David, MD
4
1Chang Gung Memorial Hospital, Taoyuan City, Taiwan; 2Washington University in St. Louis, St. Louis, MO; 3Chang Gung Memorial Hospital, Taoyuan, Taoyuan, Taiwan; 4Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Taoyuan City, Taiwan
Introduction: Neuroplasticity is the fundamental mechanism facilitating the regaining of volitional control in reinnervated muscles following nerve transfer. This study aims to compare the recovery of strength and volitional control in patients with C5-C6 brachial plexus injuries (BPIs) who underwent nerve reconstruction to restore elbow flexion. Specifically, the outcomes of transferring the posterior division of C7 to the anterior division of the upper trunk are compared to those of the double fascicular nerve transfer (DFT).
Materials and Methods: This retrospective study evaluated all C5-6 BPI patients from 2007 to 2022 receiving either ipsilateral C7 transfer or DFT for elbow flexion at a tertiary medical center. Recovery of elbow flexion was assessed in terms of strength (measured in Medical Research Council (MRC) grading) and volitional control (via the Plasticity Grading Scale (PGS) ). PGS is graded from 0 to 4, as shown in Table. Outcomes of the shoulder recovery were represented by the degree of lateral shoulder abduction.
Results: Between 2007 and 2022, 12 patients underwent ipsilateral C7, while the last 20 patients who received DFT were included for comparison. There were no significant differences between the groups in recovery percentages and time to attain MRC grade 3 [ipsilateral C7 vs. DFT: 100% vs. 80%, p=0.271] [17.12±10.91 months vs. 19.36±24.41 months, p=0.357]. In the DFT group, volitional control levels were distributed as follows: PGS1 (15%), PGS2 (30%), PGS3 (45%), and PGS4 (5%). All patients in the ipsilateral C7 transfer group achieved PGS3, demonstrating higher plasticity (PGS3-4) compared to the DFT(100% vs. 55%, p=0.012). Shoulder abduction reconstruction, performed via either intra-plexus or extra-plexus nerve transfer, showed improvement in all patients in the C7 group, with an average abduction of 88.75±53.01 degrees compared to 63.66±41.91 degrees in all C5-6 injury patients (n=84) receiving nerve reconstruction during the same period (p=0.335).
Conclusions: While both ipsilateral C7 transfer and double fascicular transfer show comparable strength recovery for elbow flexion, ipsilateral C7 transfer demonstrates superior volitional control. Furthermore, shoulder abduction function was not compromised in the C7 transfer group, making it preferable for surgeons prioritizing plasticity and for patients with limited rehabilitation resources or educational background.
| Grade | | MRC Grade of Elbow Flexion |
| Donor Command | Acceptor Command |
| 1 | Exclusively donor (no plasticity) | Best MRC grade | 0 |
| 2 | Via donor & acceptor (poor plasticity) | 2~Best MRC grade | Best MRC grade |
| 3 | Subtle via donor, predominantly | 1 | Best MRC grade |
| 4 | Exclusively acceptor (excellent plasticity) | 0 | Best MRC grade |
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