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University of Ulsan College of Medicine, Asan Medical Center, Department of Rehabilitation Medicine1, Kaiser Hospital, Department of Rehabilitation Medicine2, University of Ulsan College of Medicine, Asan Medical Center, Department of Orthopedic Surgery3 |
Object
Brachial plexus injury is a catastrophic event for patients in perspective of upper extremity motor function. To dates, for improving its functional features, various nerve transfer techniques targeting brachial plexus nerves including axillary, musculocutaneous, and suprascapular nerves are adapted and it shows outstanding results. It is well known that at least 12 months of follow up after surgery is needed to find out observable clinical improvement. Electrodiagnosis (EDX) could be used as a tool assessing nerve and functional motor unit. The purpose of this study is to find out role of pre- and early post-operative EDX as prognostic factor in brachial plexus injury patients who underwent nerve transfer operations.
Methods
In May 2017 to April 2019, 11 patients who underwent nerve transfer surgery at least one nerve involving shoulder abduction or elbow flexion were reviewed retrospectively in a single center. Additional operations such as neurolysis or nerve graft were done in some patients. Patients without periodic follow up data or diagnosed with other peripheral neuropathies which could affect patients’ function were excluded. All patients took EDX for pre- and post-operation, around 6 months after surgery. We evaluated compound muscle action potential (CMAP) ratio, which defined as target nerve CMAP out of contralateral side, motor unit recruitment and its interval changes. For evaluating motor power, we used MRC grade of shoulder, elbow, wrist, and finger after 6 and 12 months of surgery. We also used motricity index to find out that partial changes of EDX result related with whole outcome of surgery. We compared CMAP ratio, MRC grade and motricity index of pre- and post-operation. We also evaluated relationships between CMAP ratio difference, motor unit recruitment and MRC grade, motricity index changes in 6, 12 months, respectively. The Wilcoxon signed rank test, Spearman correlation coefficient and Fisher exact test were performed for statistical analysis. P < .05 was used to determine statistical significance.
Result
The average time from injury to surgery was 192 days, and the time from surgery to post EDX was 213 days. CMAP ratio, MRC grade and motricity index were significantly different before and after surgery. CMAP ratio difference in 6 months after surgery correlated with MRC grade change from baseline to 12 months of the patients. Even though there was no significant relationship between motor unit recruitment change and MRC grade change, all patients with improvement in motor unit recruitment showed better outcome in MRC grade after 12 months follow up.
Conclusions
EDX showed significant changes after surgery, and difference in CMAP ratio correlated with clinical outcomes in 1 year follow up. The result of pre- and early post-operative EDX could help establishing long term treatment plans for patients with brachial plexus injury who underwent nerve transfer surgery.
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