Effects of cisatracurium and rocuronium on intraoperative neuromonitoring and putuative mechanical trauma in 500 robotic baba thyroidectomies.

BACKGROUND

In thyroid surgery with intraoperative neuromonitoring (IONM), guidelines recommend a single intubating dose of neuromuscular blocking agent (NMBA) close to 1 × ED95 to balance intubation conditions and reliable electromyographic (EMG) signals. In robotic bilateral axillo-breast approach (BABA) thyroidectomy, however, the absence of haptic feedback raises concerns that persistent muscle relaxation could favor unrecognized mechanical trauma to the recurrent laryngeal nerve (RLN).

METHODS

We retrospectively analyzed consecutive patients undergoing elective robotic BABA thyroidectomy with IONM between April 2020 and October 2022. Patients received one of three NMBA regimens at induction: cisatracurium 0.05 mg/kg (group A), cisatracurium 0.1 mg/kg (group B), or rocuronium 0.3 mg/kg (group C). We compared intubation conditions, hemodynamics, anesthetic requirements, RLN and vagus EMG amplitudes (V1, R1, R2, V2), and perioperative outcomes, including RLN palsy, drainage, pain, and hospital stay.

RESULTS

Five hundred robotic BABA thyroidectomies were included (group A: n = 459; group B: n = 20; group C: n = 21). Across all groups, intubation conditions were consistently excellent or good. Mean EMG amplitudes for V1, R1, R2, and V2 remained within the range considered adequate for reliable IONM, with no significant differences between NMBA regimens. In group A, transient RLN palsy occurred in 2.4% of patients and resolved completely by 6 months; no permanent RLN palsy was observed. No RLN injuries were recorded in groups B and C, although these cohorts were small. Hemodynamic profiles were generally stable; cisatracurium 0.05 mg/kg was associated with less fluctuation in blood pressure and heart rate at extubation compared with cisatracurium 0.1 mg/kg. Drainage volumes, pain scores, cosmetic satisfaction, and hospital stay were comparable among groups.

CONCLUSIONS

In robotic BABA thyroidectomy with IONM, a single low dose of cisatracurium 0.05 mg/kg provides excellent intubation conditions, stable EMG signals, and low RLN morbidity, without evidence of increased mechanical trauma despite the lack of force feedback. Higher cisatracurium dose and rocuronium 0.3 mg/kg yielded similar EMG and clinical outcomes in this series, but should be interpreted as exploratory due to small sample size. These findings support low-dose cisatracurium as a practical, guideline-consistent NMBA strategy for robotic thyroid surgery with IONM.