Roles of preoperative and early postoperative electrodiagnosis in brachial plexus injury patients undergoing nerve transfer operations: retrospective feasibility study

Abstract

Objective: The purpose of this retrospective observational study was to assess the feasibility of electrodiagnostic parameters, perioperatively, and to discover optimal values as prognostic factors for patients with brachial plexus injury undergoing nerve transfer operations.

Methods: We retrospectively reviewed the records of 11 patients who underwent nerve transfer surgery. The patients underwent perioperative electrodiagnosis (EDX) before and approximately 6 months after surgery. We evaluated the compound muscle action potential (CMAP) ratio, motor unit recruitment, and their interval changes. To evaluate motor strength, we used the Medical Research Council (MRC) grade, 6 and 12 months after surgery. We evaluated the relationships between improved CMAP ratio, and motor unit recruitment and MRC grade changes 6 and 12 months postoperatively.

Results: All parameters increased significantly after surgery. The CMAP ratio improvement 6 months after surgery correlated with the MRC grade change from baseline to 12 months, with a correlation coefficient of 0.813.

Conclusion: EDX parameters improved significantly postoperatively, and the CMAP ratio improvement 6 months after surgery correlated with the clinical outcomes at 1 year. The results of perioperative EDX might help establish long-term treatment plans for patients who undergo nerve transfer surgery.

Keywords: Brachial plexus; compound muscle action potential; electrodiagnosis; nerve transfer; prognosis; rehabilitation.

Figure 1.

Relationship between CMAP ratio improvement and MRC grade change. The p-value by Spearman’s correlation between CMAP ratio improvement 6 months postoperatively and MRC grade changes 6 and 12 months postoperatively. The improvement in the CMAP ratio for early postoperative EDX and 12-month MRC grade change were significantly correlated (three points at 0,0 overlapped in the 6-month graph, and two points at 0,0 overlapped in the 12-month graph). CMAP, compound muscle action potential; MRC, Medical Research Council; EDX, electrodiagnosis.

Figure 2.

Relationship between CMAP ratio improvement and motricity index change. The p-value by Spearman’s correlation between CMAP ratio improvement 6 months postoperatively and motricity index changes 6 and 12 months postoperatively (two patients were excluded from the analysis at 6 months owing to missing data, and two points at 0,3 overlapped in the 12-month graph). CMAP, compound muscle action potential.