Phrenic nerve transfer in brachial plexus injury

A quasi-randomised study comparing phrenic nerve transfer (PNT; n=17) against intercostal nerve transfer (n=19) to the musculocutaneous nerve in 36 patients reported that motor recovery of biceps occurred significantly later in the PNT group (mean 262 days) than in the intercostal nerve transfer group (mean 195 days; p=0.03). Biceps muscle motor recovery to Medical Research Council (MRC) grade 3 (able to overcome gravity) or greater strength was reported in 29% (5 out of 17) of patients in the PNT group and 53% (10 out of 19) of patients in the intercostal nerve transfer group at 1-year follow-up. In the PNT group 23% (4 out of 17) of patients had no recovery, but all patients in the intercostal nerve transfer group regained some muscle motor function, and after rehabilitation could separate breathing from biceps function.

A case series of 40 patients treated by PNT to the anterior division of the upper trunk of the brachial plexus to restore elbow flexion reported that the biceps muscle strength recovered to MRC grade 3 or greater in 83% (33 out of 40) of patients at an average follow-up of 28.2 months. Recovery to MRC grade 3 or greater strength occurred in 91% (29 out of 32) of patients aged under 40 years, and in 50% (4 out of 8) of patients aged 40 years and over. For patients who had the procedure more than 1 year after the injury, the recovery rate was 25% (1 out of 4 patients).

A retrospective case series of 180 patients treated by PNT to the musculocutaneous nerve followed up 65 patients for more than 2 years. The study reported that 85% (55 out of 65) of patients regained biceps muscle power to MRC grade 3 or greater strength. The average time taken for restoration of muscle strength to MRC grade 3 was 9.5 months. Longer delays in treatment were associated with lower levels of recovery. Patients who had a nerve graft had similar results to patients who had a direct nerve transfer. Poor results were seen in patients with severe crush injuries and associated fractures in the shoulder region.

The specialist advisers listed key efficacy outcomes as restoration of muscle function or joint movement/elbow flexion, shoulder stability, control of re-innervated muscles and functional scores such as DASH (Disabilities of the Arm, Shoulder and Hand) and QALY (quality-adjusted life year) measures.