Objective: Either phrenic nerve transfer (PNT) or multiple intercostal nerve transfer (MIT) alone was reported having no significant impact on pulmonary function in short or medium term. But it has rarely been reported whether the combination of PNT-MIT could influence respiratory function in the long term. In this study, pulmonary and diaphragmatic functions were compared between PNT and PNT-MIT after 7 to 19 years (mean 10 years) postoperatively. Methods: Twenty-three adult patients with brachial plexus avulsion injuries (BPAI) who underwent PNT-MIT were compared with 19 corresponding adult patients who underwent PNT only. Pulmonary function testing, phrenic nerve conduction study, and chest fluoroscopy were performed to assess ventilation, diaphragmatic response, and excursion. In the PNT-MIT group, further comparison was performed to investigate whether the number of transferred intercostal nerves and the timing of MIT would influence the results. Results: In PNT-MIT group, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and total lung capacity (TLC) were 73.69%, 72.04%, and 74.81%, respectively, of predicted values without significant differences from the PNT group. Diaphragmatic paralysis permanently existed with hemidiaphragm elevation of 1 to 1.5 intercostal spaces (ICSs) and near one ICS reduced excursion. No statistically significant difference was found between PNT and PNT-MIT groups. Furthermore, in the PNT-MIT group, the transfer of 3 and 4 intercostal nerves resulted in no further decrease in pulmonary function than that of 2 intercostal nerves. No significant difference was found when PNT-MIT was performed at the same stage or at an interval of 1 or 2 months. Conclusions: In the long-term observation, PNT-MIT did not result in additional impairment in respiratory function in adult patients compared with PNT alone. Transfer of 2 to 4 intercostal nerves at 1- to 2-month delay after PNT is a safe method for treating BPAI.
