Tumor-phrenic nerve spatial relationship and intraoperative traction-induced injury during mediastinal tumor resection: implications for real-time protective strategies.

BACKGROUND

Phrenic nerve injury during mediastinal tumor resection can lead to significant postoperative diaphragmatic dysfunction. Current intraoperative protection techniques are imprecise and lack real-time feedback. We aimed to develop and validate a quantifiable, multimodal neuroprotective strategy.

METHODS

A total of 370 patients undergoing minimally invasive mediastinal tumor resection were enrolled in a two-phase cohort. Tumor-nerve spatial parameters, traction force, and intraoperative temperature were measured. The intervention group received automated cold saline irrigation and pharmacologic protection triggered by predefined thresholds.

RESULTS

Phrenic nerve injury occurred in 8.1% of the intervention group versus 18.4% in controls ( P = 0.009). Median time to diaphragmatic excursion recovery ≥1.5 cm was significantly shorter (5.2 vs 8.6 weeks, P < 0.001). LOESS curves revealed sharp inflection points in injury probability at tumor-nerve distance <4 mm, traction >10 min, and local temperature >39.5°C. Multivariate Cox analysis confirmed all three as independent predictors (HRs: 2.17, 1.88, and 2.04, respectively). At 90 days, patients in the intervention group demonstrated superior pulmonary function (FEV 1 : 2.04 vs 1.83 L), longer 6-minute walk distance (442 vs 388 m), and higher QOL scores (77.0 vs 69.4; all P < 0.01). Cost-effectiveness analysis showed average savings >$3000 and QALY gains in all tumor subtypes.

CONCLUSION

This study demonstrates that real-time, threshold-guided modulation of intraoperative mechanical and thermal stress can reduce phrenic nerve injury and enhance recovery, particularly in anatomically preserved but functionally vulnerable nerves. Rather than replacing surgical judgment, the proposed strategy provides a quantifiable, replicable adjunct for nerve preservation in technically challenging thoracic procedures.