Background: The purpose of this study was to systematically review outcomes following intercostal nerve (ICN) transfer for restoration of elbow flexion, with a focus on identifying the optimal number of nerve transfers.
Methods: A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to identify studies describing ICN transfers to the musculocutaneous nerve (MCN) for traumatic brachial plexus injuries in patients 16 years or older. Demographics were recorded, including age, time to operation, and level of brachial plexus injury. Muscle strength was scored based upon the British Medical Research Council scale.
Results: Twelve studies met inclusion criteria for a total of 196 patients. Either 2 (n = 113), 3 (n = 69), or 4 (n = 11) ICNs were transferred to the MCN in each patient. The groups were similar with regard to patient demographics. Elbow flexion ≥M3 was achieved in 71.3% (95% confidence interval [CI], 61.1%-79.7%) of patients with 2 ICNs, 67.7% (95% CI, 55.3%-78.0%) of patients with 3 ICNs, and 77.0% (95% CI, 44.9%-93.2%) of patients with 4 ICNs ( P = .79). Elbow flexion ≥M4 was achieved in 51.1% (95% CI, 37.4%-64.6%) of patients with 2 ICNs, 42.1% (95% CI, 29.5%-55.9%) of patients with 3 ICNs, and 48.4% (95% CI, 19.2%-78.8%) of patients with 4 ICNs ( P = .66).
Conclusions: Previous reports have described 2.5 times increased morbidity with each additional ICN harvest. Based on the equivalent strength of elbow flexion irrespective of the number of nerves transferred, 2 ICNs are recommended to the MCN to avoid further donor-site morbidity.
Keywords: brachial plexus; elbow flexion; intercostal nerve; musculocutaneous nerve; nerve transfer; peripheral nerve.