Semi-quantitative electromyography as a predictor of nerve transfer outcome

Abstract

Objectives: Evaluate correlation between donor nerve semi-quantitative electromyography (sqEMG) and strength outcome in nerve transfer surgery.

Methods: Retrospective review of pre-operative donor nerve semi-quantitative neurophysiology and post-operative recipient muscle force after at least one-year follow-up. The semi-quantitative technique is the average motor unit number estimate associated with needle recorded interference patterns in the donor muscle (IP-AMUNE), which was correlated with hand-held manometry, standardized as a percent of the contralateral arm, using multivariable linear regression with backward selection.

Results: Twenty-eight nerve transfer cases were included. The correlation between the donor nerve IP-AMUNE and the recipient muscle strength was moderate to strong and highly significant (r = 0.67, p < 0.001). Medical Research Council (MRC) grading did not predict strength (p > 0.54).

Conclusions: IP-AMUNE is a good predictor of strength after nerve transfer surgery and should be considered in the evaluation and planning of patients undergoing nerve transfer to aid in donor nerve selection.

Significance: IP-AMUNE may significantly benefit those undergoing nerve transfer surgery for the restoration of movement.

Keywords: Electromyography; Nerve transfer; Neurophysiology; Quantitative neurophysiology; Reconstructive neurosurgery; Spinal cord injury.